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I am field testing a few forms of items (with embedded anchor items) and will be analyzing the items using IRT, a 2PL model. These items will likely be used to create an item bank that can then create forms as needed. Can I only find the test information for each field test form or does it make sense to also find the test information for the entire group of items?

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You can find the test information function for each of your original forms if this is something you are interested in reviewing. You could also compute a test information function for the entire set of items and this could show you which ability levels are well covered by items in your item bank and which are not.

However, the test information functions of most interest (in my opinion) would be the ones for the forms that are constructed from the item bank. These will show you the range of ability levels the constructed forms are designed to evaluate. You can also include items to construct a test with a specific test information function.

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  • $\begingroup$ Thank you! This is very helpful. I was thinking that I would only be able to look at test information for each form but had seen where some people also report the test information for a group of field tests. I appreciate your explanation of how and why that might be examined or reported. Thanks again. $\endgroup$ – Daniel Jul 15 '15 at 18:01

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