At the beginning and end of a 10-week exercise program the subjects have their lung vital capacity measured by the researchers. The readings are plotted on a graph and then the results are recorded. Which of the following can pose a threat to the internal validity in this study?
A) Instrumentation
B) Selection
C) Setting
D) Testing

Question

Quizplus · Accepted Answer

Internal validity is the extent to which the effects detected in the study are a True reflection of reality rather than the result of the effects of extraneous variables. In this example the researchers must be concerned about the reliability of the instrument measuring the subjects' lung vital capacity.
Subjects are acting as their own controls. Internal validity is the extent to which the effects detected in the study are a True reflection of reality rather than the result of the effects of extraneous variables. In this example the researchers must be concerned about the reliability of the instrument measuring the subjects' lung vital capacity.
Setting would be the same in this description. Internal validity is the extent to which the effects detected in the study are a True reflection of reality rather than the result of the effects of extraneous variables. In this example the researchers must be concerned about the reliability of the instrument measuring the subjects' lung vital capacity.
Testing occurs with prescribed time periods in between. Internal validity is the extent to which the effects detected in the study are a True reflection of reality rather than the result of the effects of extraneous variables. In this example the researchers must be concerned about the reliability of the instrument measuring the subjects' lung vital capacity.

At the Beginning and End of a 10-Week Exercise Program