Can you add odds ratios?
No, unfortunately you can’t simply add the odds ratios.
Which effect measure can be used when several studies explore the same outcome OR concept but use different measurement scales?
The standardized mean difference (SMD) is used as a summary statistic in meta-analysis when the studies all assess the same outcome, but measure it in a variety of ways (for example, all studies measure depression but they use different psychometric scales).
How do you interpret odds ratio in RCT?
In an RCT or cohort study, however, the odds ratio only approximates the risk ratio if the outcome is rare or if the odds ratio is close to 1. In the RCT example, the odds ratio is (173/1,190)/(216/1,160) = 0.78 (table 2a), whereas the risk ratio is 0.81.
Which type of validity is another way of expressing internal consistency?
Discriminant validity is another way of expressing internal consistency. Attitudes are thought to have three components: affective, cognitive, and behavioral.
How to combine odds ratios from different cases?
Here the authors introduce an easy way to combine odds ratios from several case-control analyses with the same cases. The approach is based upon methods used for meta-analysis but takes into account the fact that the same cases are used and that the estimated odds ratios are therefore correlated.
Why does the odds ratio vary between control groups?
Each control group yields an odds ratio estimate, and these may vary due to chance or due to some uncontrolled confounding variable (s). For instance, observing a different effect using family controls suggests hidden genetic confounding variables.
How to compare two odds ratios for statistical significant?
This will give you the OR of Group 4 directly compared to Group 2 and also the CI and p-value. If you express these as log odds rather than odds ratios, then log odds follow a z distribution, and the Wald test for a single log-odds score (i.e. to see if it’s significantly different than zero) is simply a one-sample z test.
When to combine matched and unmatched control groups?
Conditional logistic regression ignores the unmatched cases and controls, while the matched partners are not used in unconditional logistic regression. If the 2 sets of odds ratios measure the same quantity—that is, given “infinite” samples, they would be identical—we could combine all data and obtain 1 overall, more efficient estimate.