Which type of study should be used when data are collected at ...

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Which type of study should be used when data are collected at only one point in time?
 
  a. Cross-sectional
  b. Retrospective
  c. Longitudinal
  d. Prospective

Question 2

What threat to internal validity is most closely associated with a longitudinal design?
 
  a. Instrumentation effects
  b. Mortality effects
  c. History effects
  d. Selection bias

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Answer to Question 1

ANS: A

Feedback
A Cross-sectional design is associated with data collection at one point in time.
B Retrospective design is analysis of data that has already been collected.
C Longitudinal design involves data collection over a specific period.
D Prospective design involves data collection over time into the future.

Answer to Question 2

ANS: B

Feedback
A Instrumentation effects or testing effects can occur in many types of research design and are not more likely in longitudinal design.
B A major disadvantage of longitudinal design is loss of research subjects.
C History effects can occur in any kind of research design.
D Selection bias is due to problems with sampling processes rather than design issues.

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Wow, this really help

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Gracias!