In meta-analyses the extraction and coding of information from primary
research reports has to be completed in a competent way because these
tasks implicate most of the decisions that determine the usefulness o
f the final product. The authors offer guidelines that make it more li
kely that high-quality information is reliably extracted and coded fro
m primary research reports. These guidelines address issues ranging fr
om the selection of items and construction of coding materials to sust
aining reliability and vigilance across extended periods of coding. Th
ereafter the authors note how the methodology of meta-analysis results
in pressure to change the type of information that appears in primary
research reports, and close by offering a few conjectures about the f
uture of meta-analysis.