David,
Thank you for your response. It is very helpful and much appreciated.
Shelly
Shelly Mahon
Ph.D. Candidate
University of Wisconsin-Madison
Human Development and Family Studies
1430 Linden Drive
Madison, WI 53706-1575
email: [email protected]
----- Original Message -----
From: David Jacobs <[email protected]>
Date: Wednesday, March 5, 2008 10:19 am
Subject: Re: st: linear and quadratic trend analysis
To: [email protected]
> I'm not sure that Martin answered your question although you probably
>
> already know what I'm about to say.
>
> To control for a linear trend simply construct a counter explanatory
> variable running from 1 to how many years you have; to test a
> quadratic, add the square of this explanatory variable and so on for a
> cubic.
>
> As analysis of variance allows continuous explanatory variables, this
>
> can be done in anova although most people probably would use
> regress. If you use a quadratic or cubic it would be a good idea to
> test the relevant terms for joint significance. That will help you
> decide if the higher order term is necessary.
>
> Dave Jacobs
>
> At 03:49 PM 3/4/2008, you wrote:
> >Hi there,
> >I am conducting a study using the National AddHealth data
> >set. After running factorial anovas, it is clear that I need to
> >follow up with a trend analysis. I figured out how to run graphs,
> >but does anyone have information on running the statistical tests
> >for trends. The study has four continuous outcome variables, plus
> >sex, age, and grade level with one categorical independent
> >variable. Any help is much appreciated.
> >Shelly
> >
> >Shelly Mahon
> >Ph.D. Candidate
> >University of Wisconsin-Madison
> >Human Development and Family Studies
> >1430 Linden Drive
> >Madison, WI 53706-1575
> >email: [email protected]
> >
> >*
> >* For searches and help try:
> >* http://www.stata.com/support/faqs/res/findit.html
> >* http://www.stata.com/support/statalist/faq
> >* http://www.ats.ucla.edu/stat/stata/
>
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
