Recent content by davidallsop

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    How and by what magnitude will Multiple Imputation influence my statistical results?

    Dear Forum, Hello and thank you for reading. I am a researcher based at UNSW and I have just received reviewers comments back on a manuscript that I submitted assessing the safety and efficacy of Sativex (a cannabis extract) for managing cannabis withdrawal. I have been able to address most...
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    Missing data in clinical trials - HELP! Differential drop out plus ignoring questions

    Hi, I have a long format, repeated measures dataset. I have 19 variables (columns) - all representing individual questions on a 19 item scale. For my main analysis, I use the sum total of these 19 items across each row in the dataset (and a GEE analysis, with the sum total of the 19 items as...
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    Longitudinal analysis - what to do with the baseline data?

    Hi, I have posted previously but got no response - so I am trying to narrow my search field down and articulate my questions better. If I am doing a longitudinal analysis looking at the trajectory of a dependent variable (y) over time (x) - but I have baseline measures of y at x=0-1 to...
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    Psychometrics with small datasets?

    Hi, I am developing a new measurement scale for cannabis withdrawal, but only have 50 people in my dataset (they filled the scale in every day for 3 weeks - 1 week was a baseline smoking as usual phase, the other two were abstinence from cannabis). I want to do a full psychometric...
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    Using Generalized Estimating Equations to test item validity on a scale

    Hi, I am creating a new measurement scale for withdrawal from cannabis, and have daily withdrawal data from 50 people for 1 week before abstinence (baseline smoking as usual) and then for 2 weeks of abstinence. There are 26 items on this new scale, and essentially what I want to is to rank...