Samson et al. 1986) and for males (Niemiec & Walberg 1985).
When Clark (1985) reexamined samples of the studies included in earlier meta- analyses, however, he found that effect sizes were much smaller when the same teacher provided instruction in both treatment and comparison groups and were absent when instructional method was controlled (such that the study measured the effect of instructional delivery medium only). Effects were larger in shorter-term studies, suggesting that novelty effects boost performance with new technologies in the short term but tend to wear off over time.