Sir.—In the article entitled "New Evidence on Food Additives and Hyperkinesis: A Critical Analysis" in the Journal (1980;134:1122-1124), Dr Wender made some very good comments. However, I think that the "In Rebuttal" by Drs Swanson and Kinsbourne (Journal 1980;134:1124-1125) only served to confuse the issues, and that further comment is necessary. The source of this confusion is that, although the comments by Dr Wender related to the design of the study, the rebuttal dealt mainly with the statistical analysis with which there is little fault.
My first question is as follows: Why did the baseline tests of the two groups differ before they received placebo and dye? This was a question asked by Dr Wender to which Drs Swanson and Kinsbourne said they had "no explanation." However, it was pointed out in their original article (reference 16),1 that "the difficulty of the task was adjusted for each