NOTE: Published literature tends to report statistically significant findings and may overestimate relationship between variables--referred to as “publication bias” (Whittemore, 2005). But there is debate about inclusion of grey literature because it lacks peer review. For more information see: Conn VS, Valentine JC, Cooper HM, Rantz MJ. Grey literature in meta-analyses. Nurs Res. 2003 Jul-Aug;52(4):256-61. Review. PubMed PMID: 12867783./p
