Meta Analysis Page Logo Meta - Analysis:
Methods of Accumulating Results Across Research Domains
Page 11
Home Contents Abstract Introduction Links Contact Info

Accumulating the Effect Size

After the data are converted to a common statistic, reliabilities and range departure information are collected. If all the studies include reliability estimates, or range departure data, then the effect size can be corrected at the individual study level. However, most studies do not provide this information. Fortunately Hunter and Schmidt (1990) and Hunter et al (1982) provide procedures for estimating the corrections for reliability and range departures by constructing distributions for the independent and dependent variables.

When the literature base is assembled, and reliability and range information are collected, the next step is to eliminate the bias caused by sampling error. Sampling Error refers to the random variation in study results due to sample size. Smaller sample sizes tend to vary more widely from the true relationship within the population than do studies that have large samples. Accordingly by weighting the study effect size by its sample size, will give a more accurate approximation to the relationship within the population, unaffected by the size of the sample.

Previous Home Contents Intro Top Next