Clinical Biostatistics: Geometric mean length of hospital stay exercise, suggested answer 5

5. Under Results, the authors say that “Early computed tomography reduced the length of hospital stay by 1.1 days . . . but the difference was non-significant . . . ”. What do you think of this statement?

Suggested answer

They cannot state this as a result of the study. They have no way of knowing whether the difference they observed was due to the difference in treatment. It could easily have arisen by chance, even if the treatment difference had no effect on length of stay.

They quote P=0.17 for the comparison of lengths of stay between the treatment groups. We usually take a P value greater than 0.1, as this is, as indicating little or no evidence against the null hypothesis.

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