My study was done with a group of students who took a series of tests over the course of an academic term. As a result of the study design, each response is horizontally nested within a single participant, who is in turn nested within a section. And each response is also vertically nested within a single item, which is in turn nested within a test. But I'm not interested in these particular groups of students or test items and I want to generalize my findings to other students and tests. So I have a classic case of crossed random effects.
Here's an example of my data:
Code:
* Example generated by -dataex-. To install: ssc install dataex clear input byte Participant float Section int Item byte(Test Treatment Outcome) 1 1 88 5 0 2 13 2 280 14 0 0 16 2 375 19 2 2 20 2 270 14 0 2 11 2 373 19 0 2 1 1 20 1 0 0 6 1 188 10 2 2 5 1 190 10 0 0 3 1 109 6 0 1 13 2 251 13 0 2 8 1 155 8 2 2 20 2 216 11 0 2 10 1 68 4 0 2 9 1 8 1 0 1 1 1 46 3 0 2 8 1 92 5 0 2 17 2 379 19 0 0 19 2 353 18 2 2 11 2 381 20 2 2 14 2 313 16 1 2 2 1 78 4 0 2 6 1 132 7 0 0 3 1 9 1 0 2 9 1 50 3 0 0 end
Code:
meologit Outcome Treatment || _all: R.Participant || Item:
Questions:
- For the initial approach of GLM, is this the correct code for running my analysis in meologit?
- If I'm only interested in seeing the effect of the treatment and controlling for other random effects, is there any reason to address the higher-level nesting structures of my data (participant within section and item within test)?
- If I decide to follow McNeish's advice and use GEE instead of GLM, how would I first transform my ordinal data? Can anyone point me to a study that uses GEE with categorical outcomes?
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