**CORRELATION COEFFICIENT FOR TI-84
(New OS)**

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**Problem Definition:
**Assume that you have the
following information on the heights and weights on a group of young women:

__Height x|65 |65 |62 |67
|69 |65 |61|67
__Weight y|105|125|110|120|140|135|95|130

** Method:
**First you need to
get your data in lists.

more lists, just position the cursor on the list name (L1 for example), press CLEAR; then ENTER.

Here's how to enter data:

a) Press [STAT], [ENTER]; then enter the numbers for the independent variable, x-values, in L1 and the corresponding values in L2 or whatever lists you choose.

b) After you have finished entering data, Press[STAT].

c) Move the cursor to CALC and press <8>, [ENTER] (Where <8> is just the number 8 from the keyboard.)

Note that if you want to use QuadReg or some other analysis, press the number to the left of that entry. If you chose 8, the following will appear on the home screen:

LinReg(a+bx)

Xlist:

Ylist:

Store RegEQ:

Calculate

d) If you want to graph the equation of the best-fit line, ship to item “e” below. If you have your data

in lists L

2

then press ENTER. The values for a, b, r

displayed, press 2

ANSWER: If you pressed ENTER you should have these values: a=-186.47.., b=4.705…,

r

**Graph Regression Equation:**

e) If you want to graph the regression equation, then immediately after
you enter the list names, move the cursor opposite Store RegEQ: and press VARS,
move the cursor to Y-VARS, and press

ENTER, ENTER. Y1
should appear opposite Store RegEQ

g) Press [ENTER]. After a few seconds a long equation with coefficients
having several decimal places will be stored in the Y1 graphing position.

h) To graph that, you could just press GRAPH. Depending on your data
values, you may need to adjust the WINDOW to get a good display.

i) Note that if you have already done the regression equation without
storing it in a Y-variable, you can do that as follows:

1) Press Y=; then VARS; then 5 (Statistics).

2) Cursor over to EQ and press 1 (or ENTER). The regression equation
will be stored in the Y1= position. You can then press GRAPH to graph it.

**Adding the Scatter Plot:
**First you need to do the regression graph as
described above. Now, you want to put the scatter plot on the screen with
the graph. Do that as follows:

a) Press 2ND, STATPLOT and then press ENTER, ENTER to turn plot 1 on.

b) Move the cursor to the scatter diagram for Type (the first icon) and press ENTER to highlight the scatter diagram.

c) Enter L

d) Press ZOOM, 9 (ZoomStat) and the scatter plot and the best-fit graph will appear on the screen.

e) You can press TRACE to display the x-y values on the line or press the down arrow to jump to points on the line.

f) Note that if your data has several decimal places and you would rather have fewer, you can make the data "friendlier" by making the x-distance (xmax-xmin) a multiple or sub-multiple of 9.4.

Released: 3/15/11

Last Revised: 3/15/11