A study is examining the effect of a new antilipemic drug, compared with placebo, on lipoprotein levels in postmenopausal women. Which of these actions represents the researcher's attempt at constancy in data collection to control extraneous variables?
A) Drawing the serum lipoprotein levels of all subjects at the same time of day
B) Having the same phlebotomist draw serum lipoprotein levels of all subjects
C) Using the same room for drawing blood for lipoprotein levels of all subjects
D) Ensuring that all subjects are postmenopausal women taking lipid-lowering medication

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The Answer of A study is examining the effect of a new antilipemic drug, compared with placebo, on lipoprotein levels in postmenopausal women. Which of these actions represents the researcher's attempt at constancy in data collection to control extraneous variables?
A) Drawing the serum lipoprotein levels of all subjects at the same time of day
B) Having the same phlebotomist draw serum lipoprotein levels of all subjects
C) Using the same room for drawing blood for lipoprotein levels of all subjects
D) Ensuring that all subjects are postmenopausal women taking lipid-lowering medication

A Study Is Examining the Effect of a New Antilipemic