A study is examining the effect of a new antilipemic drug, ...

[dollx]

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

Question 2

A nurse researcher assigns half a study sample to an experimental group and the other half to a control group. What does this action represent?
 
  a. Instrumentation of the independent variable
  b. Manipulation of the mediating variable
  c. Elimination of the mediating variable
  d. Manipulation of the independent variable

[enass]

Answer to Question 1

ANS: A

Feedback
A Constancy in data collection (e.g., identical timing of collecting blood samples) helps maintain control in the research design because lipid levels may fluctuate throughout the day.
B In this scenario, it is not necessary for the same person drawing blood samples to maintain constancy of measurement.
C The same room for blood draws is not necessary to maintain constancy of measurement.
D If subjects were already receiving antilipemic medication, it would be extremely difficult to distinguish the effects of the new treatment.

Answer to Question 2

ANS: D

Feedback
A Separating subjects into treatment and control groups does not represent instrumentation of the independent variable.
B A mediating or extraneous variable is usually controlled rather than manipulated.
C Separation of study subjects into treatment and control groups does not by itself eliminate mediating variables.
D Administration of a treatment or intervention to an experimental (treatment) group and not to a control group represents manipulation of the independent variable.

[dollx]

Excellent

[Liddy]

Gracias!