The distribution of birthweight of singletons in city of Tianjin, China is approximately normal with mean...

The distribution of birthweight of singletons in city of Tianjin, China is approximately normal with mean m=3,445 grams and standard deviation = 409 grams [2]. An investigator plans to conduct a study to determine if birthweight for singletons whose mothers were with gestational diabetes mellitus (GDM) have the same mean. Based on literature search, the true mean birthweight for infants whose mothers with GDM is estimated 3,800 grams (± 250 grams). The investigator wants 90% power to detect the differences. A two-tails test conducted at the 0.05 level of significance will be used. What sample size is needed for this study? if the power is changed to 80%, what sample size is then needed?

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milcah answered 1 month ago

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