Combining Effect Sizes. What to Combine? How to do it?. What to Combine? (1). Whether effect sizes can/should be combined is controversial Safe if studies are replications (identical IV, DV, design, only difference is observations)
Combining Effect Sizes
What to Combine?
How to do it?
M = 1.8/3
Unbiased, consistent, but not efficient estimator.
(cf .6 w/ unit wt)
(Unit weights are special case where w=1.)
Note that for two of three of these, the parameter is not part of the weight. For r, however, larger observed values will get more weight. Mean can be biased.