Question about Texas Instruments TI-84 Plus Silver Edition Graphic Calculator

1 Answer

LinReg gives wrong results

I teach high school physics, and students are graping and conducting a LinReg for a set of data stored in lists (e.g. LinReg L3, L2, Y1).

No problem with this, it works great, but one student was getting different values for a, b, r2, r. I checked her lists, and they were all correct. I even tried re-entering all the data, but still got the same results.

I finally cleared the RAM ([MEM] RESET ... All RAM, and now we are getting the right answer.

Any ideas of what might have been wrong?

Thanks.

Posted by on

  • Lee Trampleasure May 09, 2008

    PS. This was on a TI 84 Silver Edition, but the students who were getting the right answers were using a variety of 83/84s.

  • Laceynicole Feb 21, 2009

    I have similar problem, except now I reset it and the r and r2 are gone!!!

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  • 21 Answers

Probly because the calc was miscalibrated or someone screwed around with the variables...
hope this helps

Posted on Jun 11, 2008

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Ti 84 plus silver edition will not fit a linear model to plotted points. when I use the function vars>stat>EQ>RegEQ it transmits incomplete data in to Y=.


Your data must be in two lists L1 (for x-values), and L2 (for y-values). This is the default setting. Open the STAT utility, go to the regression models. Select your model then press ENTER. The command echoes on the main screen. For example let the regression be something called LinReg.
On the main screen you see LinReg
Complete the command line as follows
LinReg L1, L2, Y1, ENTER
You see the statistics including the regression equation.
If you go to Y= Editor you will see that Y1 contains the regression equation.
If you have already drawn the scatter plot for your data, pressing GRAPH will superpose the scatter plot and the regression curve., and you will be able to judge the goodness of the fit.

Sep 28, 2013 | Texas Instruments TI-84 Plus Silver...

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Programming in TI-84 Plus? I'm a High School student?


There is nothing wrong with your English. The problem with your request is that the program you are talking about is NO program at all, but a collection of formulas that may serve as a cheat sheet. If your teacher wanted you to make this program he would have shown you the steps to key in. Besides it would be a lot more efficient to just write these formulas on the board. Sorry, there will be no help from me.
Your formulas 2 and 3 are useless, and formulas 7 and for the real solutions of a quadratic equation are wrong. The right member should be multiplied by 1/a.
How about trying to learn your formulas by heart? It is good for your memory and you will avoid being caught cheating.

Apr 11, 2012 | Texas Instruments TI-84 Plus Calculator

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I am trying to drive a prediction equation. but the book gives directions to aTI-84 and I have a TI-89. I have these steps "STAT, EDIT, L1, L2,STAT, CALC,LinReg(ax+b), ENTER" I have no clue how to make...


I assume you know how to enter data in your calculator. The keystrokes in the following pertain to TI92/92Plus/ Voyage 200 PLT. The main differences with the TI89/Ti89 Titanium is that the function keys F6,F7,F8 are not accessed directly but by the key sequences [2nd][F1], [2nd][F2], and [2nd][F3] respectively

1. CLEAN THE SLATE (so to speak) and ENTER DATA

In Home folder run F6: NewProb to reset the configuration.
Press Apps, and select 6: data/Matrix editor. Select a new data set
84e1901.jpg

Give it a name: here testing.

2133d3f.jpg

Press OK/ENTER, The data entry screen opens, enter your values.
0ab1602.jpg

When you finish press F2.PlotSetUp.

2. Statistical plot setup and scatter plot drawing

b142867.jpg.

Press F1:define to configure Plot1. Choose Scatter, then choose a mark for the data point. I select 5:Dot. and press [ENTER
0ee40be.jpg

Select the data column X=c1, Y=c2

65437f9.jpg

Press ENTER to save configuration. Press [CTRL] [GRAPH] On my TI92 the CTRL key is the [Diamond] key. On the following graph I changed the mark to a cross to see the data point better. I also played with the window dimension. You can also do that with ZoomStat. The graph remind me of a parabola (I know I chose the exact values)

7de9410.jpg

3. STATISTICAL CALC. AND REGRESSION ANALYSES.

Now we have to find the equation that fits these data best.
You press APPS 6:Data/ Matrix editor but you select current to return to your data set. You are taken to the data entry editor (Figure 3 above). In that screen Press F5:Calc to edit the type of statistics you want

On first line select the type of regression model : Linear Regression, QuadReg quadratic regression (or anything else available) X is from column1, Y is from column 2. Store RegEQ The regression equation in say Y1(x)

7c9f572.jpg

Press ENTER to save to get the Regression Equation. Here it is
As you can see I cheated: a perfect parabola. R^2 =1.

c46b604.jpg

And here the best fit represented on same graph as the statistical data

7097bac.jpg

Usually you have to try different regression models, until you find the one that fits best the experimental data.

Jul 26, 2010 | Texas Instruments TI-89 Calculator

1 Answer

How do u store linreg(ax+b)as y1 on ur graphic calculater


When you press [STAT] and right Arrow to highlight CALC you see two linear regression model [4:LinReg(ax+b)] and [8:LinReg(a +bx)]
If you select [4: ...] the command echoes on main calculator screen as LinReg(ax+b) and a blinking cursor
If you press [ENTER] you will get your equation, a, b, and r^2 if DiagnosticsOn command has been executed before. However you will not be able to see the line of best fit on top of the raw data scatter plot.

To save the equation of best fit in a function variable, ex Y1, you complete the command as follows
LinReg(ax+b) [VARS][=>][Y-VARS][1:Function][1:Y1]
The Y1 variable will appear on main calculator screen, and you have
LinReg(ax+b) Y1
Press [ENTER]
Screen display the equation, its parameter and its correlation coefficients (if so configured).
Press [GRAPH] to draw the line of best fit on top of the scatter plot.

Here are two screen captures to show you the equation and the line of best fit.
a696143.jpg 754dc8f.jpg

As you can see from the value of r^2, and the graph, a linear regression does not seem good.

Feb 01, 2010 | Texas Instruments TI-84 Plus Calculator

2 Answers

I own a TI-84 Plus (silver edition). Does this calculator have formulas built in for the least squares line so I might enter the data to get the values for b and m? If so will it give me the correlation...


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 SetUpEditor 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 the X values in L1 and the Y values in L2 (see picture 1)
894afd6.jpg

To obtain the statistical results
  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 (with you data).
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. Some of the values your are looking for are among the result. NOW it is you mission to identify what you need (I chewed all the work for you).
However there is no correlation coefficient, no line of best fit, etc. To obtain that you have to perform a regression analysis.

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. A linear regression it will be.

  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [4:LinReg (ax+b)
  3. The command LinReg(ax+b) 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 LinReg(ax+b) 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 LinReg(ax+b) Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are your results.
2083b74.jpg
The slope is a and the y-intercept is b. 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 the raw data on the 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] to open plot1 configuration screen
  3. Use arrow to highlight On
  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 is your two graphs: the raw data scatter plot and the line of best fit on the same screen
ef0f885.jpg

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

Jan 28, 2010 | Texas Instruments TI-84 Plus Silver...

1 Answer

You are given the following data. x y 2 16 3 11 4 12 5 15 5 11 7 8 7 11 Find: - SS(x) - SS(y) - SS(xy) - The linear correlation coefficient, r - The slope b1 - The y-intercept, b0 - The equation of the...


OK, you convinced me to do your homework for you.

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 SetUpEditor 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 the X values in L1 and the Y values in L2 (see picture 1)
894afd6.jpg

To obtain the statistical results
  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 (with you data).
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. Some of the values your are looking for are among the result. NOW it is you mission to identify what you need (I chewed all the work for you).
However there is no correlation coefficient, no line of best fit, etc. To obtain that you have to perform a regression analysis.

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. A linear regression it will be.

  1. Press [STAT] , highlight [CALC]
  2. In the list of regression models select [4:LinReg (ax+b)
  3. The command LinReg(ax+b) 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 LinReg(ax+b) 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 LinReg(ax+b) Y1.
  9. Press [ENTER] to save the equation of best fit in Y1.
Here are your results.
2083b74.jpg
The slope is a and the y-intercept is b. 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 the raw data on the 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] to open plot1 configuration screen
  3. Use arrow to highlight On
  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 is your two graphs: the raw data scatter plot and the line of best fit on the same screen
ef0f885.jpg

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

N

Jan 21, 2010 | Texas Instruments TI-83 Plus Calculator

1 Answer

How do I use stat plot to graph a set of points?


Hello,
1.Press [MODE], scroll to set Function graphing mode.
2.Press [STAT] [5:SetUpEditor], command is pasted in home screen. Press [ENTER]. Screen displays Done. This clears old values in lists

3. Press [STAT][1:Edit] to enter data.
Press [ENTER] after each number. Cursor moves to next row. After finishing the data of Listt L1, use arrow right and UP to the head of list L2. Enter the values in list L2. Press Enter after last element.

4. Press [Y=] to display Y= editor. Clear function Y1 and all functions or remove highlight from the = in Y2, Y3, etc.
5.Press [2nd][STATPLOT]1 to select 1:Plot1

9d0ac15.jpg
The blinking cursor on ON means graph will be drawn. Type chosen is Scatter plot. Mark chosen is a dot.

Press [ZOOM][9:ZoomStat]
30b32c1.jpg
If you think that the curve look like a straight line you can try to do a linear regression.
Press [STAT] Arrow right to highlight [CALC]
Select [4: LinReg(ax+b)]

ccb85ed.jpg

LinReg(ax+b) echoes on run screen. Press [2nd] L1 Press comma, Press [2nd] L2 press comma Press [VARS] Arrow right to select [Y:VARs][1:Function] [ENTER][1:Y1]

68a28f1.jpgENTER
ff52832.jpg
That is the equation for the linear regression. As you see eqaution has been saved in Y1. Press [GRAPH] to get the data and the regression curve drawn on same graph.
aafb6d8.jpg

Hope it helps.


Oct 04, 2009 | Texas Instruments TI-84 Plus Calculator

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