CORRELATION COEFFICIENT FOR TI-84 (New OS)

Website Home
Mobile Web Sheets Index

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.  You can do that from the home screen, but if you have any significant amount of data, it's much easier to enter it into List tables.  If you need to clear one or  
      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 L1 and L2 as described above, enter the appropriate lists opposite Xlist and Ylist by pressing
           2ND, and the appropriate list, such as L1,  from the keyboard.  Move the cursor to “Calculate” and         
           then press ENTER.  The values for a, b, r2, and r will be displayed.  Note that if r and r2  are not 
           displayed, press 2nd , CATALOG, D, ; then scroll to DiagnosticON and press ENTER.  
            ANSWER:  If you pressed ENTER you should have these values:  a=-186.47.., b=4.705…,
           r2 =.63366…, and r=.7979…

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 L1 opposite Xlist and L2 opposite Ylist; then select the type marker you prefer, for example +.
    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

Hit Counter