A study was performed to determine the effect of introducing a low-fat diet on hormone levels of 73 postmenopausalwomennotusingexogenoushormones[15].ThedatainTable8.25 werepresentedforplasmaestradiolinlog10(picograms/milliliter).

8.99 What test can be performed to assess the effects of adopting a low-fat diet on mean plasma-estradiol levels?

8.100 Implement the test in Problem 8.99, and report a p-value.

8.101 Provide a 95% CI for the change in mean log(plasma estradiol). 10

8.102 Supposeasimilarstudyisplannedamongwomenwhouseexogenoushormones.Howmanyparticipantsneed to be enrolled if the mean change in log(plasma es-

10 tradiol)is0.08,thestandarddeviationofchangeis0.20,

and we want to conduct a two-sided test with an level of.05 and a power of .80?

Change in plasma estradiol after adopting a low-fat diet

Estradiol log10(pg/mL)a

tablE 8.25

PreinterventionPostintervention0.63 (0.26) Difference(postintervention - preintervention) 0.08 (0.20)

aValues are mean and sd (in parentheses) for log (base 10) ofpreintervention and postintervention measurements and for their difference.

(Rosner 328)

Rosner, Bernard. Fundamentals of Biostatistics,8th Edition. Cengage Learning, 20150803. VitalBook file.

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