Which situation represents a threat to internal validity in an ...

[xroflmao]

Which situation represents a threat to internal validity in an experimental study measuring the effect of a videotape of discharge instructions for patients who underwent coronary artery bypass graft (CABG) surgery?
 
  a. Both men and women undergoing CABG surgery were included as subjects in the study.
  b. Two new surgeons began performing CABG surgery during the study period.
  c. Patients in the experimental group discussed aspects of the videotape with patients in the control group.
  d. Data collection for the videotape and control groups took 1 year.

Question 2

A nurse researcher should consider mortality a threat to the study's internal validity for which of these reasons?
 
  a. There is concern that the intervention may have harmful effects on subjects.
  b. Those who dropped out of the study may be different than those who remained in the study.
  c. Those who participated in the study may have died as a result of being in the study.
  d. There is concern that the design is inappropriate for the study question if a large number of participants drop out of a study.

[meltdown117]

Answer to Question 1

ANS: C

Feedback
A Including both genders would strengthen the design and would not threaten internal validity.
B Personnel factors like surgeons' newly performing the procedure should not directly affect the treatment and threaten internal validity.
C Sharing aspects of the videotape with control group members interferes with interpretation of the true effect of the independent variable on the dependent variable(s).
D Duration of data collection does not threaten internal validity, provided the control processes were standardized.

Answer to Question 2

ANS: B

Feedback
A Mortality does not refer to harmful aspects of an intervention but to attrition of subjects in a study.
B Subjects who drop out or who are otherwise lost from a study may differ in some important way from remaining subjects and therefore threaten internal validity.
C Mortality does not refer to treatment-related negative consequences in a study.
D Loss of a large number of subjects does not necessarily make a design inappropriate for the study question.

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TYSM

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Gracias!