In a letter to the Journal of Nursing Research, Brown and Allison write:
We question the conclusions that a health promotion model “was highly effective for gaining healthy life behaviors and the control of BMI of the participants” in an article recently published in The Journal of Nursing Research (Fidanci, Akbayrak, & Arslan, 2017). The authors are to be commended for several aspects of their study, but here we note one major error . . .
Our interest relates to the obesity outcome of children’s BMI standard deviation scores (SDS) reported in Table 3. The authors reported that there was a significant difference over time within the experimental group, but not within the control group, and on that basis they conclude there is a difference between groups. This comparison is known as the Differences in Nominal Significance (DINS) error . . . In this particular case, the medians, as reported, show a change in medians of -0.1 BMI SDS in each of the two groups; one of the changes was sta- tistically different from baseline, whereas the other was not. However, when we directly compare the point estimates of changes in medians as reported in the summary statistics, there is no difference in the change in medians between groups; the difference of differences is zero. . . .
Fidanci, Akbayrak, and Arslan reply:
We would like to thank you for your insightful comments . . . You are correct in pointing out that we mistakenly identified a significant difference over time within the experimental group but not within the control group and that, based on this, we mistakenly identified a difference between the groups. Although nominal significance may have been achieved within each group, a difference between the groups is not supported. . . . These results suggest that education, while highly effective for engendering healthy life behaviors, had no effect on controlling the BMI of the participants (Table 3). We have made the necessary changes to the results section in order to reflect the above.
However, the above mistake is not repeated in the other tables in this study, where the results of comparisons between groups are reported. For example, in Table 2, a statistically significant difference between the experimental and control groups was found . . .
So refreshing to see people just accept that they made a mistake and move on, not fighting it. Wouldn’t it be great if it was like this all the time.