134 10: Running Total and Statistics
To do curve fitting and forecasting :
1. Enter the data into two SUM lists: one for the x-values and one for the
y-values. Make sure each list has the same number of items so that the
items are in matched pairs.
2. From the SUM menu, press E ) —
to display a menu
of SUM-list names. The current list is labeled
˜
unless named
otherwise.
3. Press a menu key to select a list of x-values (independent variable).
4. Select a list of y-values (dependent variable).
5. Now you see the FRCST menu. Whichever curve-fitting model was
used last is named in the display. If you want to select a different
model, press
) œ
,
and then the menu key for the model.
6. To calculate the curve-fitting results, press, ™
,
š
and
›
.
7. To forecast (estimate) a value:
a. Key in the known value and press the menu key for that variable.
b. Press the menu key for the variable whose value you want to
forecast.
Example: Curve Fitting. BJ’s Dahlia Garden advertises on a local radio
station. For the past six weeks, the manager has kept records of the
number of minutes of advertising that were purchased, and the sales for
that week.
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