Does Item Order or Context Matter?

Tom Snider-Lotz asked, and some of the answers were ...

David Andrich: It is always an empirical matter with every particular data set (collection of items and persons) whether the item order is independent in the sense that is required by the model, and therefore that order will not matter. However, there are good testing reasons, reflected by the model, for having items independent. For example, we do not want one item imply the answer to another and so on. If students are to do a set of items, it is not helpful to independence and good testing to put the most difficult items first. It will upset the students and they will not be able to do the ones that they could do later in the test had they been earlier in the test.

Jack Stenner: We have conducted a number of [in-house] studies over the last decade on the effects of context on reading item calibrations. Context includes variation due to person sample, placement on the test, and resolution of location indeterminacy via a text analysis of all items on the test. We have found a rather consistent context effect of slightly more than .40 logits. Of course, the effect on the mean item difficulty, which is what matters most when making person measures, is reduced proportional to the square root of the number of items. Thus "ambient noise", which is what we call this irreducible variation in item difficulty, would contribute on average only .40/7 logits of error to the centering on a 49 item test.

Bryce Reeve: Lynne Steinberg did some analyses .... and found a context effect.

"Question order effects [in questionnaires] have been found to reliably influence an item's item-total correlation (Knowles, 1988), item-trait correlation (Steinberg, 1994), slope parameter ..., and reliability (Knowles & Byers, 1996)." (Assessing Performance: Investigation of the Influence of Item Context using Item Response Theory Methods. Kuang, D.C., & Steinberg, L., 2004 Annual Meeting of the Society of Industrial and Organizational Psychology, Chicago, IL.)

Knowles, E. S. (1988). Item context effects on personality scales: Measuring changes the measure. Journal of Personality and Social Psychology, 57, 351-357.

Knowles, E. S. & Byers, B. (1996). Reliability shift in measurement reactivity. Driven by content engagement or self-engagement? Journal of Personality and Social Psychology, 70, 1080-1090.

Steinberg, L. (1994). Context and serial-order effects in personality measurement: Limits on the generality of measuring changes the measure. Journal of Personality and Social Psychology, 66, 341-349.

Does item order or context matter?, Snider-Lotz T, Andrich D, Stenner J, Reeve B … Rasch Measurement Transactions, 2004, 18:3 p. 991

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