Let's say I have 30 studies, where each study measures a dichotomous outcome and has a dichotomous predictor. Some people have multiple responses, so I use a GEE to model every one of the 30 studies. What I have is a log-odds coefficient for each (via `coef(model)[2]` for each study), as well as the variance for each of these coefficients (via `diag(vcov(model))[2]` for each study). Note that no covariates are added to the model. The only coefficients are the intercept and the one for the dichotomous predictor. Two questions for everyone: 1. Can I assign the coefficients (in logits?the log of the odds ratio) to `yi` and the variances to `vi` from these GEE models and submit them directly to `rma.uni()`? I am assuming here that the coefficients and variances are all I need, and the `escalc` function says we should be converting odds ratios to log-odds anyways. Note that there are no dependencies *across *studies, so the robust variance estimates from the GEE should capture all the dependencies. 2. If I can do that, what is the recommended way to present this to non-statistical audiences? I can get a meta-analytic estimate for the log of the odds ratio, but my clients are used to seeing risk differences (e.g., "There was a +4 percentage point lift"). I could always convert log-odds to odds ratios and then compute lifts from a variety of different baselines (e.g., "If there was a 50% positive outcome in the control, then we had a +3.5 percentage point lift"). Any other ideas? Thanks, Mark
[R-meta] Meta-analyzing ORs from GEEs
2 messages · Mark White, Michael Dewey
Inline
On 29/08/2018 03:13, Mark White wrote:
Let's say I have 30 studies, where each study measures a dichotomous outcome and has a dichotomous predictor. Some people have multiple responses, so I use a GEE to model every one of the 30 studies. What I have is a log-odds coefficient for each (via `coef(model)[2]` for each study), as well as the variance for each of these coefficients (via `diag(vcov(model))[2]` for each study). Note that no covariates are added to the model. The only coefficients are the intercept and the one for the dichotomous predictor. Two questions for everyone: 1. Can I assign the coefficients (in logits?the log of the odds ratio) to `yi` and the variances to `vi` from these GEE models and submit them directly to `rma.uni()`? I am assuming here that the coefficients and variances are all I need, and the `escalc` function says we should be converting odds ratios to log-odds anyways. Note that there are no dependencies *across *studies, so the robust variance estimates from the GEE should capture all the dependencies.
That seems OK to me since you state there are no other covariates to worry about.
2. If I can do that, what is the recommended way to present this to non-statistical audiences? I can get a meta-analytic estimate for the log of the odds ratio, but my clients are used to seeing risk differences (e.g., "There was a +4 percentage point lift"). I could always convert log-odds to odds ratios and then compute lifts from a variety of different baselines (e.g., "If there was a 50% positive outcome in the control, then we had a +3.5 percentage point lift"). Any other ideas?
That seems a good idea. Never heard lift used in that sense but if that is their preferred term it is perfectly clear. Michael
Thanks, Mark [[alternative HTML version deleted]]
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