DIAGNOSTICS ON
     This process only needs to be done ONCE, before you do your first linear regression

2nd-0    (For CATALOG)
    Type D - and arrow down to DiagnosticOn - and press ENTER

Enter Data
Enter Data x and y  into to lists , say L1 and L2

Scatter Plot
Establish the picture desired:
      2nd - Stat Plot  -  TYPE:  is first one,   and Xlist is L1  and YList is L2

View the picture:
      ZOOM - 9:ZoomStat   to see Picture

    *NOTE:    Y=     and CLEAR  removes any lines being graphed on StatPlot
 
Equation of Line

         STAT   "right arrow"     CALC     4:LinReg(ax+b)  L1,L2

Record   y =ax + b     specific values of  a and b

If you have turned Diagnostics on early, the r and r^2 values will appear after a and b
 

    Alternative method to find r
         VARS    5:Statistics   "right arrow"  "right arrow"         EQ       7:r     ENTER
             will print r on home screen

Graphing Equation of Line
         Y=     VARS  5:Statistics    "right arrow"  "right arrow"          EQ  1:RegEQ
              will paste equation of line into Y1=

         *NOTE:  CLEAR  when in Y=    will remove equation of previous line

Predicting  y  for additional values of x

     1.   If the r  value is significant, then put the particular  x into the equation and find y
            *With calculator, if you have the equation of line in Y=,   then
              GRAPH,    2nd CALC  (on top row)     1:value   ENTER  and enter x value

     2.   If the r  value is NOT significant, then  is the best prediction that can be made. 
            To find  , find mean(L2)