Question about Texas Instruments TI-83 Plus Calculator

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Whenever i enter coordinates for a scatter plot or best fit line the point do not show up neither does the line i can trace the points and the calculator tell the coordinates but they are not visible

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  • Texas Instru... Master
  • 7,993 Answers

Two possibilities:

  1. Graph is out of range (out of the window). If your data is positive set Xmin=0 and Ymin=0. Set Xmax a bit larger than the maximum x-value and YMAX a bit larger than the maximum y-value. You can also press [ZOOM] and select [9:ZoomStat].
  2. To mark the points you may have select the dot and your calculator screen is too dim.
To help you setup your calculator To perform regression analysis I am inserting here a copy of a more detailed post of mine where I show the complete procedure applied to a quadratic regression.

Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
  1. Press [2nd][ ] (MEM) to open the memory management screen.
  2. Press [4:ClrAllLists]
  3. The command echoes on main screen, press [ENTER] to run it.
  4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
  1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DIAGNOSTICSON option. To access the command
  1. You press [2nd] [0] (CATALOG)
  2. While the list of commands is displayed, press [X^-1] (D)
  3. Cursor jumps to first command that starts with D, dayOfWk(
  4. Press the DownArrow 9 times to reach DIAGNOSTICSON
  5. Select it and press [ENTER]
  6. Command echoes on main calculator screen with blinking cursor
  7. Press [ENTER] to set the option
  8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA
Press [STAT][1:Edit]
Type in your D (X ) values in L1 and the N (Y) values in L2 (see picture 1). Sorry the picture does not have YOUR values.
whenever i enter coordinates for - 894afd6.jpg

TO OBTAIN statistical RESULTS (optional)
  1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
  2. Press [STAT] and highlight Menu (CALC)
  3. In the list select [2:2-Var Stats]
  4. Command echoes on main screen.
  5. Press [ENTER] to calculate the stats
Here is what one gets with the data above.

f2d3743.jpg
Notice the Down Arrow next to n=7. That means the results screen has more values. Press the Down Arrow to displawhenever i enter coordinates for - ab847d7.jpgg src="http://i.fixya.net/uploads/images/ab847d7.jpg" alt="ab847d7.jpg" class="h_mi" />
You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here iswhenever i enter coordinates for - 37fb2ba.jpgf the statistical results.
37fb2ba.jpg
There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the statistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have To perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimics the raw data best. Select Regression model ( exponential, linear, sine, quadratic, etc.) Here I selected Exponential
  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [0:ExpReg]
  3. The command ExpReg echoes on main calculator screen.
  4. If you press [ENTER], you'll get your equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
  5. While ExpReg command is still in command line, press the [VARS] key.
  6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
  7. In the Y function variable list select [1:Y1]
  8. At the command line, you have ExpReg Y1.
  9. Press [ENTER] to save the equation of best fit iwhenever i enter coordinates for - f07d40f.jpg/ol>Here are your results. (These are your actual results)
    f07d40f.jpg
    You also have r and its square.

    Since the equation is saved in the Y1 function it can be superposed on the scatter plot. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

    F. DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

    Regardless of the curve of best fit, you can draw a scatter plot as follows.
    1. Press [2nd][Y=] (STATPLOT)
    2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
    3. Use arrow to highlight On and press ENTER
    4. Use the Down Arrow to move cursor to the line Type.
    5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the righwhenever i enter coordinates for - b3dea28.jpgrrow (to backtrack), but not the Up or down arrows.
    Here is the configuration screen
    b3dea28.jpg
    Here plot1 is active (ON), it is scatter plot (first icon) the XLIST is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
    On the line Mark you can choose the appearance of the raw data point.

    And here are your whenever i enter coordinates for - d6e8e98.jpg the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.
    d6e8e98.jpg
    The graph above represents a parabola and has nothing to do with the sample data entered. But it shows the raw data and the curve of best fit on the same screen.

Posted on Sep 05, 2010

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I am trying to do a project and i need to find the sine regression on the TI-84 PLus Silver Edition calculator. Can you please tell me how to do that?


Here is a copy on an earlier post I made detailing how to do a regression on a TI8x Plus families of calculators. In the post I took a quadratic regression, but that should not be a problem for you to use the same techniques. Just, when you reach the point where you select the regression model, select SinReg.
If you follow the instructions you should be able to get the scatter plot and the best-fit curve on the same graph. If you do get an error check your data and blame not the method I will show you because it is sound.

Here it goes
Your question is a very interesting one and I believe people will benefit from a complete solution to it. So I will provide a solution for a quadratic regression.
The points I will represent are those on a parabola
L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}
As you can see, I am cheating (no experimental points will fit a perfect parabola) but this will have no incidence on what I am going to show you.

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.
8b83b2e.jpg
2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]
57b097c.jpg
to open the list editing screen. Enter the elements of the two lists
d10bb96.jpg
After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below
d653a12.jpg
Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to Xlist
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)
e825b96.jpg
DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get
0d9dbd0.jpg

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

b12881c.jpga7fbc6b.jpg
Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitly on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen
30d1079.jpg
Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

2757d7c.jpg
The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

e380d1f.jpg
Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line
0b6bc57.jpg
After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

3e957b3.jpg
As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get
e481e00.jpg

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.
ad6b3c2.jpg

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
  • bc62328.jpg
Type in the value and press [ENTER] et voil?.
7fd58d3.jpg
If as I have suggested above, you copied the regression equation to Y1 variable, you can calculate Y-values for any X in the graph domain.

In Main calculator screen type the numerical value of X, say 4.777756, and store it in X-variable

4.777756 [STO>] [X,T,theta,n] [ENTER]

Calculator answers Done

Press [VARS][>][Y-VARS][1:Function...][1:Y1] [ENTER]

The calculator computes the value of Y1 for the entered value of X.
You can also generate a whole table, but you will have less control over the points where Y1 will be calculated.

Feb 13, 2011 | Texas Instruments TI-84 Plus Calculator

1 Answer

I cannot figure out how to do a Quadreg


Your question is a very interesting one and I believe people will benefit from a complete solution to it. So I will provide a solution for a quadratic regression.
The points I will represent are those on a parabola
L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}
As you can see, I am cheating (no experimental points will fit a perfect parabola) but this will have no incidence on what I am going to show you.

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.
8b83b2e.jpg
2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]
57b097c.jpg
to open the list editing screen. Enter the elements of the two lists
d10bb96.jpg
After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below
d653a12.jpg
Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to Xlist
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)
e825b96.jpg
DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get
0d9dbd0.jpg

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

b12881c.jpga7fbc6b.jpg
Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitly on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen
30d1079.jpg
Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

2757d7c.jpg
The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

e380d1f.jpg
Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line
0b6bc57.jpg
After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

3e957b3.jpg
As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get
e481e00.jpg

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.
ad6b3c2.jpg

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
  • bc62328.jpg
Type in the value and press [ENTER] et voilà.
7fd58d3.jpg
If as I have suggested above, you copied the regression equation to Y1 variable, you can calculate Y-values for any X in the graph domain.

In Main calculator screen type the numerical value of X, say 4.777756, and store it in X-variable

4.777756 [STO>] [X,T,theta,n] [ENTER]

Calculator answers Done

Press [VARS][>][Y-VARS][1:Function...][1:Y1] [ENTER]

The calculator computes the value of Y1 for the entered value of X.
You can also generate a whole table, but you will have less control over the points where Y1 will be calculated.

Dec 08, 2010 | Texas Instruments TI-84 Plus Silver...

1 Answer

Create a scatter plot of the data


The drawing of the scatter plot proper is explained in the last part (Part F). You might want to jump right to it.


Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
  1. Press [2nd][+] (MEM) to open the memory management screen.
  2. Press [4:ClrAllLists]
  3. The command echoes on main screen, press [ENTER] to run it.
  4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
  1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DIAGNOSTICSON option. To access the command
  1. You press [2nd] [0] (CATALOG)
  2. While the list of commands is displayed, press [X^-1] (D)
  3. Cursor jumps to first command that starts with D, dayOfWk(
  4. Press the DownArrow 9 times to reach DIAGNOSTICSON
  5. Select it and press [ENTER]
  6. Command echoes on main calculator screen with blinking cursor
  7. Press [ENTER] to set the option
  8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA
Press [STAT][1:Edit]
Type in your D (X ) values in L1 and the N (Y) values in L2 (see picture 1). Sorry the picture does not have YOUR values.
894afd6.jpg

TO OBTAIN statistical RESULTS (optional)
  1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
  2. Press [STAT] and highlight Menu (CALC)
  3. In the list select [2:2-Var Stats]
  4. Command echoes on main screen.
  5. Press [ENTER] to calculate the stats
Here is what you get (THESE~ARE NOT YOUR RESULTS). Your results will be different.
f2d3743.jpg
Notice the Down Arrow next to n=7. That means the results screen has more values. Press the Down Arrow to display.
ab847d7.jpg
You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here is the rest of the statistical results.
37fb2ba.jpg
There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the statistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have To perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimicks the raw data best. Select Regression model (Example Exponential, linear, sine, quadratic, etc.) Here I selected Exponential
  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [0:ExpReg]
  3. The command ExpReg echoes on main calculator screen.
  4. If you press [ENTER] you will get your equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
  5. While ExpReg command is still in command line, press the [VARS] key.
  6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
  7. In the Y function variable list select [1:Y1]
  8. At the command line, you have ExpReg Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are your results. (These are your actual results)
f07d40f.jpg
You also have r and its square.

Since the equation is saved in the Y1 function it can be superposed on the scatter plot. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

F. DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

Regardless of the curve of best fit, you can draw a scatter plot as follows.
  1. Press [2nd][Y=] (STATPLOT)
  2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
  3. Use arrow to highlight On and press ENTER
  4. Use the Down Arrow to move cursor to the line Type.
  5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the right or left arrow (to backtrack), but not the Up or down arrows.
Here is the configuration screen
b3dea28.jpg
Here plot1 is active (ON), it is scatter plot (first icon) the XLIST is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
On the line Mark you can choose the appearance of the raw data point.

And here are your two graphs: the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.
d6e8e98.jpg

Now, it is up to you to accept this model or to try another model.

Nov 06, 2010 | Texas Instruments TI-84 Plus Calculator

1 Answer

How do i find the line of best fit on my TI-84 plus addition?


Here is a complete solution that shows you how to find the equation for the best curve fitting, how to draw that equation on the same screen as the scatter plot and also how to do interpolation or the best fit curve. The post may seem long for an impatient reader but it leaves no stone unturned. Please DO READ it till the end.

The data points used are for a parabola (QuadReg) but you can easily adapt it

The points I will represent are those on a parabola (squares of all integer numbers from 0 to 10). Substitute your own values in L1 and L2

L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.
8b83b2e.jpg
2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]
57b097c.jpg
to open the list editing screen. Enter the elements of the two lists
d10bb96.jpg
After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below
d653a12.jpg
Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to Xlist
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)
e825b96.jpg
DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get
0d9dbd0.jpg

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

b12881c.jpga7fbc6b.jpg
Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitly on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen
30d1079.jpg
Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

2757d7c.jpg
The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

e380d1f.jpg
Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line
0b6bc57.jpg
After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

3e957b3.jpg
As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get
e481e00.jpg

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.
ad6b3c2.jpg

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
  • bc62328.jpg
Type in the value and press [ENTER] et voil

Sep 01, 2010 | Texas Instruments TI-84 Plus Silver...

1 Answer

How do i find and use the regression capabilties of my calculator?



Your question is a very interesting one and I believe people will benefit from a complete solution to it. So I will provide a solution but I will apply it to a quadratic regression.
The points I will represent are those on a parabola
L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}
As you can see, I am cheating (no experimental points will fit a perfect parabola) but this will have no incidence on what I am going to show you.

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.
8b83b2e.jpg
2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]
57b097c.jpg
to open the list editing screen. Enter the elements of the two lists
d10bb96.jpg
After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below
d653a12.jpg
Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to XList
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)
e825b96.jpg
DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get
0d9dbd0.jpg

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

b12881c.jpga7fbc6b.jpg
Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitely on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen
30d1079.jpg
Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

2757d7c.jpg
The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalaog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

e380d1f.jpg
Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line
0b6bc57.jpg
After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

3e957b3.jpg
As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get
e481e00.jpg

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.
ad6b3c2.jpg

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
  • bc62328.jpg
Type in the value and press [ENTER] et voilà.
7fd58d3.jpg
If as I have suggested above, you copied the regression equation to Y1 variable, you can calculate Y-values for any X in the graph domain.

In Main calculator screen type the numerical value of X, say 4.777756, and store it in X-variable

4.777756 [STO>] [X,T,theta,n] [ENTER]

Calculator answers Done

Press [VARS][>][Y-VARS][1:Function...][1:Y1] [ENTER]

The calculator computes the value of Y1 for the entered value of X.
You can also generate a whole table, but you will have less control over the points where Y1 will be calculated.

Aug 24, 2010 | Texas Instruments TI-84 Plus Calculator

2 Answers

I made a scatter graph with a linear regression and now want to find values for points on the graph that are not my original plotted points ie if X is 50 what is Y or if Y is 5 what is X where these were...


Your question is a very interesting one and I believe people will benefit from a complete solution to it. So I will provide a solution but I will apply it to a quadratic regression.
The points I will represent are those on a parabola
L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}
As you can see, I am cheating (no experimental points will fit a perfect parabola) but this will have no incidence on what I am going to show you.

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.
8b83b2e.jpg
2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]
57b097c.jpg
to open the list editing screen. Enter the elements of the two lists
d10bb96.jpg
After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below
d653a12.jpg
Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to XList
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)
e825b96.jpg
DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get
0d9dbd0.jpg

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

b12881c.jpga7fbc6b.jpg
Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitely on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen
30d1079.jpg
Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

2757d7c.jpg
The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalaog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

e380d1f.jpg
Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line
0b6bc57.jpg
After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

3e957b3.jpg
As you can see both are represented

TRACING THE REGRESSION CURVE (Sorry it took so long to arrive to the point)
Press Trace and see what you get
e481e00.jpg

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.
ad6b3c2.jpg

If you want Y for a particular value of X, just enter the value of X


Jul 20, 2010 | Texas Instruments TI-84 Plus Calculator

1 Answer

I need to find the equation for some points with my calculator but they are for an exponential regession. How do I do this?


Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
  1. Press [2nd][+] (MEM) to open the memory management screen.
  2. Press [4:ClrAllLists]
  3. The command echoes on main screen, press [ENTER] to run it.
  4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
  1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DiagnosticsOn option. To access the command
  1. You press [2nd] [0] (CATALOG)
  2. While the list of commands is displayed, press [X^-1] (D)
  3. Cursor jumps to first command that starts with D, dayOfWk(
  4. Press the DownArrow 9 times to reach DiagnosticsOn
  5. Select it and press [ENTER]
  6. Command echoes on main calculator screen with blinking cursor
  7. Press [ENTER] to set the option
  8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA
Press [STAT][1:Edit]
Type in your D (X ) values in L1 and the N (Y) values in L2 (see picture 1). Sorry the picture does not have YOUR values.
894afd6.jpg

TO OBTAIN THE STATISTICAL RESULTS (optional)
  1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
  2. Press [STAT] and highlight Menu (CALC)
  3. In the list select [2:2-Var Stats]
  4. Command echoes on main screen.
  5. Press [ENTER] to calculate the stats
Here is what you get (THESE~ARE NOT YOUR RESULTS). Your results will be different.
f2d3743.jpg
Notice the down arrow next to n=7. That means the results screen has more values. Press the down arrow to display.
ab847d7.jpg
You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here is the rest of the statistical results.
37fb2ba.jpg
There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the satistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have to perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimicks the raw data best. In this particular case, you have already decided to do a linear regression, and that is good for me. I do not have the time to take you through all of them. In this step you must select the exponential regression model.
  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [0:ExpReg]
  3. The command ExpReg echoes on main calculator screen.
  4. If you press [ENTER] you will get you equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
  5. While ExpReg command is still in command line, press the [VARS] key.
  6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
  7. In the Y function variable list select [1:Y1]
  8. At the command line, you have ExpReg Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are your results. (These are your actual results)
f07d40f.jpg
You also have r and its square. You need to read your theory to know which of the two correlation coefficients you have been asked to obtain.

Since you saved the equation in the Y1 function you can draw it. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

Regardless of the curve of best fit, you can draw a scatter plot as follows.
  1. Press [2nd][Y=] (STATPLOT)
  2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
  3. Use arrow to highlight On and press ENTER
  4. Use the down arrow to move cursor to the line Type.
  5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the right or left arrow (to backtrack), but not the Up or down arrows.
Here is the configuration screen
b3dea28.jpg
Here plot1 is active (ON), it is scatter plot (first icon) the Xlist is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
On the line Mark you can choose the appearnce of the raw data point.

And here are your two graphs: the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.
d6e8e98.jpg

Now, it is up to you to accept this model or to try another model.

May 13, 2010 | Texas Instruments TI-84 Plus Calculator

2 Answers

How do I create a scatter plot?


The drawing of the scatter plot proper is explained in the last part (Part F). You might want to jump right to it.


Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
  1. Press [2nd][+] (MEM) to open the memory management screen.
  2. Press [4:ClrAllLists]
  3. The command echoes on main screen, press [ENTER] to run it.
  4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
  1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DIAGNOSTICSON option. To access the command
  1. You press [2nd] [0] (CATALOG)
  2. While the list of commands is displayed, press [X^-1] (D)
  3. Cursor jumps to first command that starts with D, dayOfWk(
  4. Press the DownArrow 9 times to reach DIAGNOSTICSON
  5. Select it and press [ENTER]
  6. Command echoes on main calculator screen with blinking cursor
  7. Press [ENTER] to set the option
  8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA
Press [STAT][1:Edit]
Type in your D (X ) values in L1 and the N (Y) values in L2 (see picture 1). Sorry the picture does not have YOUR values.
894afd6.jpg

TO OBTAIN statistical RESULTS (optional)
  1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
  2. Press [STAT] and highlight Menu (CALC)
  3. In the list select [2:2-Var Stats]
  4. Command echoes on main screen.
  5. Press [ENTER] to calculate the stats
Here is what you get (THESE~ARE NOT YOUR RESULTS). Your results will be different.
f2d3743.jpg
Notice the Down Arrow next to n=7. That means the results screen has more values. Press the Down Arrow to display.
ab847d7.jpg
You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here is the rest of the statistical results.
37fb2ba.jpg
There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the statistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have To perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimicks the raw data best. Select Regression model (Exeample Esponential, linear, sine, quadratic, etc.) Here I selected Exponential
  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [0:ExpReg]
  3. The command ExpReg echoes on main calculator screen.
  4. If you press [ENTER] you will get you equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
  5. While ExpReg command is still in command line, press the [VARS] key.
  6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
  7. In the Y function variable list select [1:Y1]
  8. At the command line, you have ExpReg Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are your results. (These are your actual results)
f07d40f.jpg
You also have r and its square.

Since the equation is saved in the Y1 function it can be superposed on the scatter plot. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

F. DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

Regardless of the curve of best fit, you can draw a scatter plot as follows.
  1. Press [2nd][Y=] (STATPLOT)
  2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
  3. Use arrow to highlight On and press ENTER
  4. Use the Down Arrow to move cursor to the line Type.
  5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the right or left arrow (to backtrack), but not the Up or down arrows.
Here is the configuration screen
b3dea28.jpg
Here plot1 is active (ON), it is scatter plot (first icon) the XLIST is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
On the line Mark you can choose the appearance of the raw data point.

And here are your two graphs: the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.
d6e8e98.jpg

Now, it is up to you to accept this model or to try another model.
Comments: Apr 19, 2010 - I tried to edit the post to address your particular need but after several crashes I decided to paste it as is.
The particular parts that are of concern to you are Part E (performing a regression analysis) and the following one where the best fit and the dcatter plot are superposed on the same display.

As you have guessed you must select QuadReg.

Apr 30, 2010 | Texas Instruments TI-84 Plus Calculator

1 Answer

How to Plot & graph or Model Quadratic on the same screen. I want to plot the points from adta table & then using Quad regression I got the equation ,but I can't graph on the same screen as the...


Read this post. It answers all your questions and shows you HOW to do find your equation of best fit, correlation coefficients, etc.

Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
  1. Press [2nd][+] (MEM) to open the memory management screen.
  2. Press [4:ClrAllLists]
  3. The command echoes on main screen, press [ENTER] to run it.
  4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
  1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DiagnosticsOn option. To access the command
  1. You press [2nd] [0] (CATALOG)
  2. While the list of commands is displayed, press [X^-1] (D)
  3. Cursor jumps to first command that starts with D, dayOfWk(
  4. Press the DownArrow 9 times to reach DiagnosticsOn
  5. Select it and press [ENTER]
  6. Command echoes on main calculator screen with blinking cursor
  7. Press [ENTER] to set the option
  8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA
Press [STAT][1:Edit]
Type in your D (X ) values in L1 and the N (Y) values in L2 (see picture 1). Sorry the picture does not have YOUR values.
894afd6.jpg

TO OBTAIN THE STATISTICAL RESULTS (optional)
  1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
  2. Press [STAT] and highlight Menu (CALC)
  3. In the list select [2:2-Var Stats]
  4. Command echoes on main screen.
  5. Press [ENTER] to calculate the stats
Here is what you get (THESE~ARE NOT YOUR RESULTS). Your results will be different.
f2d3743.jpg
Notice the down arrow next to n=7. That means the results screen has more values. Press the down arrow to display.
ab847d7.jpg
You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here is the rest of the statistical results.
37fb2ba.jpg
There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the satistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have to perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimicks the raw data best. In this particular case, you have already decided to do a linear regression, and that is good for me. I do not have the time to take you through all of them. In this step you must select the exponential regression model.
  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [0:ExpReg]
  3. The command ExpReg echoes on main calculator screen.
  4. If you press [ENTER] you will get you equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
  5. While ExpReg command is still in command line, press the [VARS] key.
  6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
  7. In the Y function variable list select [1:Y1]
  8. At the command line, you have ExpReg Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are your results. (These are your actual results)
f07d40f.jpg
You also have r and its square. You need to read your theory to know which of the two correlation coefficients you have been asked to obtain.

Since you saved the equation in the Y1 function you can draw it. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

Regardless of the curve of best fit, you can draw a scatter plot as follows.
  1. Press [2nd][Y=] (STATPLOT)
  2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
  3. Use arrow to highlight On and press ENTER
  4. Use the down arrow to move cursor to the line Type.
  5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the right or left arrow (to backtrack), but not the Up or down arrows.
Here is the configuration screen
b3dea28.jpg
Here plot1 is active (ON), it is scatter plot (first icon) the Xlist is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
On the line Mark you can choose the appearnce of the raw data point.

And here are your two graphs: the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.
d6e8e98.jpg

Now, it is up to you to accept this model or to try another model.

Apr 16, 2010 | Texas Instruments TI-84 Plus Silver...

1 Answer

I need to find the equation for some points with my calculator, but they are for an exponential regession. How do I do this?


Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
  1. Press [2nd][+] (MEM) to open the memory management screen.
  2. Press [4:ClrAllLists]
  3. The command echoes on main screen, press [ENTER] to run it.
  4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
  1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DIAGNOSTICSON option. To access the command
  1. You press [2nd] [0] (CATALOG)
  2. While the list of commands is displayed, press [X^-1] (D)
  3. Cursor jumps to first command that starts with D, dayOfWk(
  4. Press the DownArrow 9 times to reach DIAGNOSTICSON
  5. Select it and press [ENTER]
  6. Command echoes on main calculator screen with blinking cursor
  7. Press [ENTER] to set the option
  8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA (ENTER your own data)
Press [STAT][1:Edit]
Type in your X values in L1 and the Y values in L2 (see picture 1).
894afd6.jpg

TO OBTAIN the statistical RESULTS (optional)
  1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
  2. Press [STAT] and highlight Menu (CALC)
  3. In the list select [2:2-Var Stats]
  4. Command echoes on main screen.
  5. Press [ENTER] to calculate the stats
Here is a sample of what one gets .
f2d3743.jpg
Notice the Down Arrow next to n=7. That means the results screen has more values. Press the Down Arrow to display.
ab847d7.jpg
You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here is the rest of the statistical results.
37fb2ba.jpg
There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the statistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have To perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimicks the raw data best. In this particular case, you have already decided to do a linear regression, and that is good for me. I do not have the time to take you through all of them. In this step you must select the exponential regression model.
  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [0:ExpReg]
  3. The command ExpReg echoes on main calculator screen.
  4. If you press [ENTER] you will get you equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
  5. While ExpReg command is still in command line, press the [VARS] key.
  6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
  7. In the Y function variable list select [1:Y1]
  8. At the command line, you have ExpReg Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are sample results.
f07d40f.jpg
You also have r and its square. You need to read your theory to know which of the two correlation coefficients you have been asked To obtain.

Since you saved the equation in the Y1 function you can draw it. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

Regardless of the curve of best fit, you can draw a scatter plot as follows.
  1. Press [2nd][Y=] (STATPLOT)
  2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
  3. Use arrow to highlight On and press ENTER
  4. Use the Down Arrow to move cursor to the line Type.
  5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the right or left arrow (to backtrack), but not the Up or down arrows.
Here is the configuration screen
b3dea28.jpg
Here plot1 is active (ON), it is scatter plot (first icon) the XLIST is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
On the line Mark you can choose the appearnce of the raw data point.

And here are your two graphs: the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.
d6e8e98.jpg

Now, it is up to you to accept this model or to try another model.

Mar 21, 2010 | Texas Instruments TI-84 Plus Calculator

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