Finally, there is a latent problem when counting only published researches. While the article
review process helps guarantee the quality of published works, a publication bias may product
from the tendency that researches with significant findings or larger effect sizes are more
likely to be published than those without significant findings or with smaller effect sizes. This
difficulty is generally related to as the ‘file drawer’ difficulty in that these unpublished works
are hidden away in ‘file drawers’ (Wolf, 1986 and Hay et al., 2006).