True. Meta-analysis is a statistical technique that takes all the correlations found in studies of a particular relationship and calculates a weighted average. Correlations based on studies with small samples are weighted more than correlations based on studies with large samples. This is because studies with larger samples are generally more reliable and provide a more accurate estimate of the true correlation between variables. By weighting the correlations based on sample size, meta-analysis provides a more accurate estimate of the true correlation between variables than any individual study. Therefore, the statement that meta-analysis takes all the correlations found in studies of a particular relationship and calculates a weighted average is true.