Date:         Wed, 7 Dec 2005 07:32:46 -0800
Reply-To:     dave@AUTOBOX.COM
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         dave@AUTOBOX.COM
Organization: http://groups.google.com
Subject:      Re: Forecasting Time Charter Rates
Comments: To: sas-l@uga.edu
In-Reply-To:  <200512071008.jB75w4O3020379@mailgw.cc.uga.edu>
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The phenomena that you describe is why we have written FreeFore .

The following are some ofthe things that FreeFore checks for ..

. Is there need to transform the data to stabilize the variance of the
residuals via either power transforms ( e.g. logs,reciprocals, square
roots etc ) or is there evidented structural break points in variance .

Is there or has there been a change in parameters over time ?
suggesting that parameters estimated for the ENTIRE TIME RANGE may be
inadequate thus suggesting local estimation.

Do the residuals suggest an evidented LEVEL SHIFT , or SEASONAL PULSE
oe LOCAL TIME TREND or one or more PULSES (inliers/outliers) ?

Is there a need to incorporate lags or leads of any of your suggested
CAUSAL VARIABLES ?

For more see

http://www.autobox.com/Freefore-over.htm

If I can help ... please call

Dave Reilly
automatic forecasting systems
http://www.autobox.com
215-675-0652