Quartz | Level 8

## reg or autoreg or arima

Ok, my scenario is like this.  I have prices of certain (5 types) cars that go as back as 15 years by month, and by zipcodes (30 of them).  I also have some other variables such as household income and unemployment %, which I want to attempt to use in forecasting the changes in auto prices in the next 12 months.  Arima woks, I know, but I'd have to do a model for each auto type (5) per each zipcode (30) = 150 models.  Can I use Regression and just get one model and have the same variables in the model and would it work?.. how about AUTOREG, since I don't know much about it?  thanks

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Fluorite | Level 6

## reg or autoreg or arima

Hi,

I'm getting the feeling you don't fully understand the meaning of Time-Series analysis.

here is a nice start :

http://www.abs.gov.au/websitedbs/d3310114.nsf/4a256353001af3ed4b2562bb00121564/b81ecff00cd36415ca256...

and a nice article about arima models:

http://www.duke.edu/~rnau/411arim.htm

now to answer your question: I do mean the dependent variable (which is aso the independent variable in AR models). and you can use it for both autoreg and arima.

take care

3 REPLIES 3
Fluorite | Level 6

## reg or autoreg or arima

Hi,

I believe what you are looking for is The arimax method (which is the same as arima but with independent variables).

I would recommend inquiring each series separately so you can look at the structure of each series (unless you are looking for the average price of all car models.).

BTW: why not using the difference between each time period ? (T2/T1-1)

about AUTOREG - it is a simplier form of arima (AUTOREGRESSION-INTEGRATED-MOVING_AVERAGE)

hope this helps.

keep posting

Quartz | Level 8

## reg or autoreg or arima

Thank you dekelas, very helpful info.

When you say  difference between each time period, do you mean as the dependent variable?, and for both ARIMA and AUTOREG ?

Also, do you think just a Multiple Regression model would work fine with this data, and just use time as an independent variable..??

Fluorite | Level 6

## reg or autoreg or arima

Hi,

I'm getting the feeling you don't fully understand the meaning of Time-Series analysis.

here is a nice start :

http://www.abs.gov.au/websitedbs/d3310114.nsf/4a256353001af3ed4b2562bb00121564/b81ecff00cd36415ca256...

and a nice article about arima models:

http://www.duke.edu/~rnau/411arim.htm

now to answer your question: I do mean the dependent variable (which is aso the independent variable in AR models). and you can use it for both autoreg and arima.

take care

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