In control of diabetes it is important to know how blood glucose levels change after eating various foods. Ten volunteers participated in a study to compare the effects of two foods -a sugar and a starch. A blood specimen was drawn before each volunteer consumed a measured amount of food: then additional blood specimens were drawn at 11 times during the next 4 hours. Each volunteer repeated the entire test on another occasion with the other food. Of particular concern were blood glucose levels that dropped below the initial level; the accompanying table shows the number of such values.

Suppose we analyze the given data as a contingency table. The test statistic would be

At α = 0.05 we would reject H0 and find that there is sufficient evidence to conclude that blood glucose values below the initial value occur more often after ingestion of sugar than after ingestion of starch. This analysis contains two flaws. What are they?

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No. of values lessTotal number than initial value Food Sugar Starch of observations 110 110 26 14. (26 20) (14 20)2 20 (84-90 (96 90y 20 (84-90)2 90 (96-90)2 90 = 4.40 , 、