Texas Instruments TI-83 Manual Book page 328

To see the magnitudes of the residuals, continue with these steps.
29. Press r.
Press ~ and | to trace the data. Observe the
values for
With this model, the largest positive residual is
about 0.041 and the smallest negative residual
is about L0.027. All other residuals are less
than 0.02 in magnitude.
Now that you have a good model for the relationship between length and
period, you can use the model to predict the period for a given string
length. To predict the periods for a pendulum with string lengths of 20 cm
and 50 cm, continue with these steps.
30. Press  ~
secondary menu, and then press
FUNCTION
select
1:Y
1
TI-83 Plus Statistics
at each point.
Y
to display the
1
. is pasted to the home screen.
Y
1
VARS Y.VARS
to
1
325