HP 3000 Manuals

HP RXForecast Users Manual for MPE Systems

Interval Type Option 

The Interval Type option appears on the RXForecast Options command dialog
box.

The Interval Type option allows you to select the type of statistical
interval--prediction or confidence--or no interval type at all.

Confidence Interval 


            

If Confidence Interval is selected, the interval type pertains to mean
values around the trend line.  That is, it defines a range in which the
average of the predicted values will fall for a given percentage of the
time.  (This percentage is chosen through the Confidence Level option.)

For example, if you have chosen a Confidence Level of 90 percent, 90
percent of all true mean values will fall within the upper and lower
limits.  The line is a projection of the average trend.

The graph below depicts a Confidence Interval type.


            

Prediction Interval 


            

If Prediction Interval is selected, the interval type pertains to bounds
for the individual points of the trend line.  That is, it defines a range
in which the predicted value (all points) will fall a given percentage of
the time.

For example, if you have chosen a Confidence Level of 90 percent, 90
percent of all points will fall within the upper and lower limits.  This
selection will naturally yield an interval with a much wider spread than
does a Confidence Interval type.

The only difference between the following graph and that shown above is
the choice of Interval Type.  The following graph depicts a prediction
type of interval.


            

MPE/iX 5.0 Documentation