Re: Fwd: What is the best approach for my research?

Posted by Jon K Peck on Feb 23, 2012; 2:02pm
URL: http://spssx-discussion.165.s1.nabble.com/What-is-the-best-approach-for-my-research-tp5507150p5508174.html

Rasch models are available in Statistics via several extension commands.

STATS IRM fits a 3-parameter item response model
STATS GRM fits a graded response model to ordinal data
SPSSINC RASCH estimates an item response model

All of these can be downloaded from the SPSS Community website (www.ibm.com/developerworks/spssdevcentral)  The R Essentials, also available from that site, is a prerequisite.


Jon Peck (no "h") aka Kim
Senior Software Engineer, IBM
[hidden email]
new phone: [phone]




From:        Benjamin Spivak <[hidden email]>
To:        [hidden email]
Date:        02/23/2012 06:20 AM
Subject:        [SPSSX-L] Fwd: What is the best approach for my research?
Sent by:        "SPSSX(r) Discussion" <[hidden email]>

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Hi Ryan,

Thank you very much, I will look at Rasch models and attempt to apply it to my work. Could I trouble you with another question. 

Say, I do find that there is a uni-dimensional construct underlying comprehension. How could this assist me to look for differences between conditions?

Regards,

Ben


On 23 February 2012 23:41, R B <ryan.andrew.black@...> wrote:
Benjamin,

The first thing I would consider would be whether there is an underlying unidimensional construct underlying comprehension. You could fit a Rasch model via Winsteps, which allows for items with varying response options.

Ryan


On Thu, Feb 23, 2012 at 1:14 AM, Benjamin Spivak <benjamin.spivak@...> wrote:
Dear List,
 
Please help I am stuck. I am performing some jury research with some very strange result and I want to find the ideal statistical model to fit my data.
 
My study. Essentially a 2x3 jury simulation study measuring comprehension of law. I also have over 18 DV's (questions) for comprehension. I have considered condensing the questions into one variable. But Cronbach's alpha is quite low for any combination of questions that I can relate to one construct.
 
Distribution is extremely non-normal and there is a heterogeneity of variance between groups. Also, because the jury study uses deliberating groups I have violated the assumption of independence.
 
Considering all this, I am having real trouble determining what the best approach for analysis would be. I have tried multi-level linear modelling, but I get results that I cannot make sense of.
 
I am at my wits end. If somebody could help, I would be in their debt.
 
Regards,
 
Ben.
 
 
 
 I would like to analyze individual jury data, but clearly my model violates the assumption of independence. So I have to account for this.