[Rasch] Rasch Analysis on Vignette Instruments
rmt at rasch.org
Fri Aug 12 06:37:24 EST 2011
Dare Institute, thank you for asking our advice.
You write: "the participant will rate highly the vignette that corresponds
to the stage he/she is at, and that the participant will give lower ratings
to the other vignettes."
This indicates that the data are "folded". Since you have a theory about
the hierarchy of the vignette-items, you can "unfold" the data, into
"0=participant below this level", "1=at this level", "2=above this level".
If participants were perfectly self-consistent, this would produce a
perfect Guttman Scalogram.
So an immediate suggestion is to recode the data into 0,1,2 and then do a
rating-scale analysis. If this analysis produces promising findings, then
the next stage would be to make the recoding more elaborate.
At 8/11/2011, you wrote:
>In each instrument, five or more vignettes are presented. .....
Editor, Rasch Measurement Transactions
rmt at rasch.org www.rasch.org/rmt/ Latest RMT: 25:1 Summer 2011
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