Unfortunately this is the only procedure I have to create a forecast. Do you know of an option that will limit my output in a specific range?
In other words, i want my estimated value to be within a specif range.
Unfortunately, Proc Reg is not a good tool for forecasting . It is usually used to interpolation ,not extrapolation.
"estimated value to be within a specif range"
Did you mean confidence interval ? CI is such a option.
Ksharp
Following on to Ksharp's response that PROC REG is not a good tool for forecasting, what you might do is run PROC REG and get the Durbin-Watson autocorrelation statistic. If it is not extreme, then extrapolation may be good for at least short projections ahead.
But to limit the response to a specified range is difficult. You could create the CI on the predicted values, and when it exceeds your range, state that the model is good only out to that point.
Another approach could be to apply a differencing schema to your data in an attempt to introduce stationarity. You still have the problem of extrapolation, but autocorrelation should be reduced. Produce the confidence interval at each extrapolated time point. Back-calculate the values from the differenced predicted values, and see how far out you can still meet your pre-specified range.
One more thought: I really don't know of any methodology that allows you to limit the range of predicted values for extrapolated independent variables a priori. If someone does, I would be very, very interested in learning about it.
Steve Denham
Don't miss out on SAS Innovate - Register now for the FREE Livestream!
Can't make it to Vegas? No problem! Watch our general sessions LIVE or on-demand starting April 17th. Hear from SAS execs, best-selling author Adam Grant, Hot Ones host Sean Evans, top tech journalist Kara Swisher, AI expert Cassie Kozyrkov, and the mind-blowing dance crew iLuminate! Plus, get access to over 20 breakout sessions.
Learn the difference between classical and Bayesian statistical approaches and see a few PROC examples to perform Bayesian analysis in this video.
Find more tutorials on the SAS Users YouTube channel.