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THOMAS E. WISWELL, MD
9016 First Ave Silver Spring, MD 20910

Am J Dis Child. 1989;143(11):1259-1260.

	Since this article does not have an abstract, we have provided the first 150 words of the full text PDF and any section headings.

Sir.—The article by Hanson et all in the October 1988 issue of AJDC somewhat supported a personal belief that ischemic injury is involved in the propagation of necrotizing tracheobronchitis (NTB). However, I do not believe that their data justify a causal relationship, as the title of the article would imply. Although 58 infants with NTB had either profound hypotension or low 5-minute Apgar scores (the "ischemia" factors that differentiated them from the controls), the remaining 64 affected infants (54%) had neither of these factors. Furthermore, the authors state that their data were analyzed with "a two-tailed t test."¹ I suspect that they actually meant that X² analysis was used. Simplistically, the t distribution is a method of com= paring two group means, while the X² statistic compares rates or frequencies of discrete findings. The P values presented in the tables are actually those that one would . . . [Full Text PDF of this Article]

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