In my stats class today, the professor was showing us some output from MINITAB on a prediction interval that was calculated (from time series data using standard linear regression). For one of the prediction intervals (which I believe was a forecast in the future), MINITAB had an X marked with the statement that there was an outlier in the prediction interval.
I searched the MINITAB documentation and can't find a satisfactory explanation for how a computed prediction interval can contain an outlier.
Does anyone know what this means? I know the SE of the PI increases with distance from xbar, but what criterion would you judge to determine the PI is "too wide" (which is what I assume the program is doing)
TIA, Matt