To the Editor.—I read with great interest the article by Hodgson et al1 on the effects of pentoxifylline on the survival of skin flaps. There has been much speculation on this subject, and definitive research is wanting. However, the data presented by Hodgson and associates make it difficult to draw conclusions. The first ambiguity lies in their use of the Student t test. Are they applying this test to the 70 flaps or to the six pigs? This is not being statistically picky, since the flaps are not independent samples (yet, the t test would treat them as such, with 69 degrees of freedom) and the pigs are (with 5 degrees of freedom). Another ambiguity is that no beta error was calculated. It has been recommended that all statistically negative results (ie, P >.05) be tested for beta error.2 Briefly, it is the probability of saying a difference
VELANOVICH V. Effects of Pentoxifylline on the Survival of Skin Flaps. Arch Otolaryngol Head Neck Surg. 1988;114(6):681. doi:10.1001/archotol.1988.01860180095047
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