Question

Rye County Hospital’s Wellness Center is testing two programs to get smokers to quit. STOP is offered on Tuesday nights, and QUIT is offered on Thursday nights. Ninety smokers volunteered to be subjects. They will be randomly assigned to STOP, QUIT, or No Treatment (neither group).

A. What two threats to internal validity are controlled by random assignment?

B. Just about the time when the smoking study started, cigarette taxes increased sharply. Would this increase affect the internal validity of the study? Explain your answer.

C. Several subjects assigned to QUIT had a schedule conflict with their aerobics class. Before the program began, an administrative assistant let them trade places with subjects assigned to STOP. Comment on how the assistant's action may affect the study’s internal validity.

D. STOP and QUIT began in the same week and then ended in the same week at the study's completion. At the last session of the STOP program, data on the subjects’ smoking behavior were gathered. The analysts forgot to gather the same data from the QUIT subjects. Three weeks later, the oversight was discovered, and the data were collected. Comment on how the oversight may have affected the study’s internal validity.

E. What is the value of having a No Treatment group?

Answer 1

Answer:

A. Random assignment  controls choice inclination and development as dangers to inside legitimacy. The member bunches shaped by full intensity of arbitrary task are equivalent inside the cutoff points of irregular mistake, when the treatment starts.

B. There is a decent shot that the sharp increment in the expense of cigarettes influence the inward legitimacy of the investigation. This alludes to the effect of history or occasions outside of the investigation or between rehashed proportions of the reliant variable that may influence members' reactions.

C. This demonstration may result in two kinds of dangers to inward legitimacy. Dissemination perhaps saw as the treatment impacts can spread from treatment gatherings to control gatherings. Moreover, there can likewise be compensatory competition or angry dampening in light of which conduct in the control gatherings might be adjusted.

D. Here, instrumentation appears to have occured. This alludes to dangers that happen because of changes in the appraisal of the needy variable. Almost certainly, members from the QUIT gathering may have overlooked something it experienced outside changes in 3 weeks.