title: Type II (beta) errors in the hand literature: the importance of power.
abstract: When a study concludes that there is no difference between 2 treatments ("negative studies"), it is essential to determine whether the study has sufficient power to find a clinically significant difference. Insufficient power precludes an adequate assessment of therapeutic efficacy and may result in a type II error, an erroneous conclusion that the null hypothesis is correct. In evaluating 39 studies that highlighted negative findings in The Journal of Hand Surgery, we found that 32 (82%) papers had a power of less than .80 to detect a 25% treatment effect and, when the treatment effect was increased to 50%, more than one half of the studies still had a power of 0.80. These "negative studies" frequently have inadequate statistical power to support their conclusions. These findings have important implications for researchers, editors, and readers.
authors.affiliation: Section of Plastic and Reconstructive Surgery, University of Michigan Medical Center, Ann Arbor 48109-0340, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Chung
authors.forename: L K
authors.initials: LK
authors.lastname: Kalliainen
authors.forename: R A
authors.initials: RA
authors.lastname: Hayward
mesh_terms: D000818:Animals; D005188:False Negative Reactions; D005189:False Positive Reactions; D006225:Hand / Q000601:surgery*; D006801:Humans; D011336:Probability; D011643:Publishing; D012107:Research Design; D013223:Statistics as Topic