How to do a Validation Study?

#1
My professor has asked me to do a validation study but I have never done one before and don't know what methodology or statistics to use. Basically the original study took a personality assessment with 27 scales and compared it to an ADHD assessment. A stepwise regression identified six scales that were responsible for a large proportion of variance in the ADHD assessment. A MANOVA identified six subscales that significantly differed between those with ADHD and those without.

I was asked to validate one or both of the original statistics. Any suggestions on methodology or statistical analyses? Or any validation studies you can recommend I read that may be similar?

Thanks!!
 

spunky

Doesn't actually exist
#2
are you familiar with factor analysis/structural equation modeling?

it would also be helpful if you're familiar with "The Standards for Educational and Psychological Testing" (aka [URL="http://www.apa.org/science/programs/testing/standards.aspx]the Standards[/url]). everything that has to do with validity and validation there is in the first chapter