Research synthesis. Coding and conjectures

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 of the final product. The authors offer guidelines that make it more likely that high-quality information is reliably extracted and coded from primary research reports. These guidelines address issues ranging from the selection of items and construction of coding materials to sustaining reliability and vigilance across extended periods of coding. Thereafter, 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 future of meta-analysis.