To summarize, of the studies that have directly investigated the Council et al. (1986) context hypothesis, only three partially supported the context hypothesis, and three reported negative results. There were no entirely positive reports that supported the context hypothesis.

This issue may be difficult to deal with at the level of the individual study. An alternative to the single study approach is to use the techniques collectively known as meta-analysis. This is a method of integrating the results of a set of independent studies that address a related set of questions. Unlike traditional research or review methods, meta analysis uses the summary statistics from individual studies as the data points in the analysis. A key assumption of this kind of analysis is that each individual study provides a differing estimate of the underlying relationship within the population. By accumulating results across studies one gains a more accurate view of the population relationship than what is provided by the individual studies.

Using this procedure, each individual study is examined and categorized according to an established coding scheme. The results are then converted to a common statistic, known as the effect size. The effect sizes are aggregated according to the coded variables and statistically analyzed. Cooper & Hedges (1994); Hunter, Schmidt & Jackson (1982), Hunter & Schmidt, (1990); Rosenthal (1991a and 1991b), and Wolf (1986) provide more detail on this review method.

Using the present literature base as an example, although there are only six studies that directly examine the contextual effects on the TAS and hypnotizability relationship, a cursory examination of the literature reveals that much of the available research on the relationship between the TAS and hypnotic susceptibility has enough procedural details to categorize each study as measuring the TAS in or out of a hypnotic context.