Re: Time series- Seasonal ARIMA model

Posted by David Marso on Jan 07, 2013; 8:51pm
URL: http://spssx-discussion.165.s1.nabble.com/Time-series-Seasonal-ARIMA-model-tp5717193p5717257.html

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FWIW:  Time series analysis is a non trivial, relatively advanced topic in the statistical sciences.  Once upon a time in a previous century when I took a full semester course in ARIMA models, transfer functions and the like were relegated to the last few weeks of study AFTER the less complicated issues were well understood.
Before taking this course one had to have about 4 prerequisite courses under their belts including a full semester in GLM/Regression/ANOVA which followed introductory and intermediate courses.
Somehow it seems that statistics has become so much 'simpler', that anyone can push a button and be a 'statistician'... Real Stats Real Easy... Caveat Emptor!!!  GIGO...
This applies even more to the wanna be SEM aspirants... Draw a pretty picture and BOOM!!!
If you think it is expensive to hire a professional wait until you engage a novice!
</RANT>
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tomdireill wrote

Monali,

You will also need to be on the lookout for outliers.  You should be searching for pulses outliers, level shifts, seasonal pulses and changes in trend.

These are not often discussed and when ignored can make you think you should be differencing when in fact if you had just built a level shift you would have the correct model.

Tom