Rapid responses from bmj.com

doi:10.1136/bmjusa.03020005

BMJ, doi: 10.1136/bmjusa.03020005, (Published 26 March 2003)

Letters

Clarification needed about possible bias and statistical testing

Consenting adults?

The first 150 words of the full text of this article appear below.

From BMJ USA 2003;Feb:93

RAPID RESPONSES FROM BMJ.COM Following are edited excerpts from Rapid Responses generated by this article, which can be readin their entirety at http://bmj.com/cgi/eletters/325/7377/1391. $---$ Editor

Clarification needed about possible bias and statistical testing

EDITOR $---$ I have two concerns about this study. First, I would like to know exactly what participants were told about the study(perhaps the authors could make the letter sent to participantsavailable on bmj.com). This is important because of the subjectivenature of participants' responses. If participants had any reasonto suspect the nature of the study hypothesis, this could haveintroduced substantial bias into theresults.

Second, their choice of statistical method is rather strange. The t-test is designed for use with continuous, interval-level,normally distributed data. Use of a t-test on the discrete, ordinaldata reported in this paper is questionable. A more appropriatestatistical method would have been a non-parametric test, a comparison. . . [Full text of this article]