The drawing of the scatter plot proper is explained in the last part (Part F). You might want to jump right to it.
doing statistics, you have to prepare the calculator by clearing old
data that may generate errors.A. TO CLEAR OLD DATA
B. RUN the
SETUP EDITOR Command
- Press [2nd][+] (MEM) to open the memory management
- Press [4:ClrAllLists]
- The command echoes on main screen, press [ENTER] to run
- Calculator displays Done.
C. TURN DIAGNOSTICSON option
- Press [STAT][5:SetUpEditor] [ENTER] ; calculator
obtain the correlation coefficient in a statistical analysis on the
TI8xPlus family of calculators you must activate the DIAGNOSTICSON
option. To access the command
- You press [2nd]  (CATALOG)
- While the list of commands is displayed, press [X^-1]
- Cursor jumps to first command that starts with D,
- Press the DownArrow 9 times to reach DIAGNOSTICSON
- Select it and press [ENTER]
- Command echoes on main calculator screen with blinking
- Press [ENTER] to set the option
- 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
Type in your D (X ) values
and the N (Y) values in L2 (see picture 1). Sorry the picture does not
have YOUR values.TO
OBTAIN statistical RESULTS (optional)
- After you finish entering the data, press [2nd][Quit]
to exit StatEditor.
- Press [STAT] and highlight Menu (CALC)
- In the list select [2:2-Var Stats]
- Command echoes on main screen.
- Press [ENTER] to calculate the stats
what you get (THESE~ARE NOT YOUR RESULTS). Your results will be
the Down Arrow
next to n=7. That means the results screen has more
values. Press the Down Arrow
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
is no arrow at the bottom of the picture. End of statistical results.
captures with 2-Var Stats summarize all the statistics
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
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
- Press [STAT] , highlight [CALC]
- In the list of regression models select [0:ExpReg]
- The command ExpReg echoes on main calculator
- 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.
- While ExpReg command is still in command line,
press the [VARS] key.
- Highlight the [Y-VARS] menu and select [1:Function],
then press [ENTER].
- In the Y function variable list select [1:Y1]
- At the command line, you have ExpReg Y1.
- Press [ENTER] to save the equation of best fit in Y1.
are your results. (These are your actual results)
also have r and its square.
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
of the curve of best fit, you can draw a scatter plot as follows.
- Press [2nd][Y=] (STATPLOT)
- Select [1:Plot1...Off] and press ENTER to open plot1
- Use arrow to highlight On and press ENTER
- Use the Down Arrow to move cursor to the line Type.
- 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.
is the configuration screen
is active (ON), it is scatter plot (first icon) the XLIST
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
On the line Mark you can choose the appearance
of the raw
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
option was used.
it is up to you to accept this model or to try another model.
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
superposed on the same display.
As you have guessed you must