[Rasch] Using Winsteps to compute scores
talilij at yahoo.com
Mon Feb 4 21:05:19 EST 2013
We developed a 36-item self-administered survey instrument that will be
used to measure the performance of "recollection facilitators". The
instrument consists of five subscales with items that used a five-point
ordered response options. For the scoring, it is tedious in the part of
the user if the scores shall be computed by subscale. Thus, we plan to
rasch analyze the entire scale (the 36 items together) and then produce
the scores by respondents across items using Winsteps. Then, from that
scores, the user can easily compute the scores by subscale. However, we afraid because Rasch analysis of the entire scale, instead of by
subscale, might be wrong. To check if we are not wrong, we do the two
analyses as follows:
Analysis 1: We Rasch analyze by subscale and then produce the scores by subscale.
Analysis 2: We Rasch analyze the entire scale and then produce the scores by subscale.
Then, for each subscale we will draw scatterplot of the scores generated from the two analysis. Analysis 1 and analysis 2 are the same if the points in the scatterplot will form a straight line. Are we correct?
Any comments are welcome.
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