[Rasch] Item arrangement and measure invariance

Agustin Tristan ici_kalt at yahoo.com
Sat Sep 12 08:27:17 EST 2009

There is a paper by Ronald N. Marso: Test item arrangement, testing time and performance. Journal of Educational Measurement, 1970, vol.7, pp. 113-118, where the author concludes: "One need not be greatly concerned with arranging items by difficulty, in order of class presentation, or by similarity of content covered at least in terms of influencing required testing time or student performance".
I suppose (and I think many of us do as well) that, according to Marso, item arrangement may produce variations in performance or modify the item difficulty, but those variations are not significant. If the items are independent, the individual item difficulty is an intrinsic property of the item plus or minus the  interval defined by  Zc x standard error (generally 2 x SE). 
This invariance of measure and difficulty makes sense for CAT and the construction of item banks.
A discussion here is that a new item arrangement will produce significantly different difficulties, and worse: always produce higher difficulties. I cannot find a reason to say that a different arrangement of the items will produce SYSTEMATICALLY HIGHER values of the difficulty.
I need more recent references (even PhD thesis) to this regard and your opinion about this.

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