Author Question: Why is the threat of subject attrition more problematic in longitudinal designs than in other types ... (Read 86 times)

Collmarie

  • Hero Member
  • *****
  • Posts: 569
Why is the threat of subject attrition more problematic in longitudinal designs than in other types of descriptive research?
 
  a. Subjects are elderly.
  b. Data analysis is complex, and missing data points necessitate dropping the subject from the analysis.
  c. Data collection occurs over a much longer period of time.
  d. There is selection bias because of the study requirements.

Question 2

Why does subject attrition affect internal validity?
 
  a. A study in which the majority of the subjects die calls into question whether the treatment itself is safe.
  b. Subjects who drop out may differ from those who stay in the study, in terms of an important extraneous variable.
  c. If subjects drop out of the control group, and not the experimental group, it strongly implies that there is some benefit to participation of which the researchers may not be aware.
  d. Subject mortality may result in a sample that is so much smaller than anticipated that type II error may result.
  e. Type I error is almost guaranteed with very unequal sample sizes.



sierramartinez

  • Sr. Member
  • ****
  • Posts: 313
Answer to Question 1

ANS: C
Longitudinal designs examine changes in the same subjects over time. They are expensive and require a long period of researcher and subject commitment. Measurement must be carefully planned and implemented, because the measures will be used repeatedly over time. There is often a bias in selection of subjects because of the requirement for a long-term commitment. In addition, loss of subjects (attritionsubject quits participating in the study) can be high and can decrease the validity of findings.

Answer to Question 2

ANS: B, C
The subject attrition threat is due to subjects who drop out of a study before completion. Participants' attrition becomes a threat when (1) those who drop out of a study are a different type of person from those who remain in the study or (2) there is a difference between the kinds of people who drop out of the experimental group and the people who drop out of the control or comparison group



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
 

Did you know?

Liver spots have nothing whatsoever to do with the liver. They are a type of freckles commonly seen in older adults who have been out in the sun without sufficient sunscreen.

Did you know?

Green tea is able to stop the scent of garlic or onion from causing bad breath.

Did you know?

Vaccines prevent between 2.5 and 4 million deaths every year.

Did you know?

Many medications that are used to treat infertility are injected subcutaneously. This is easy to do using the anterior abdomen as the site of injection but avoiding the area directly around the belly button.

Did you know?

Although the Roman numeral for the number 4 has always been taught to have been "IV," according to historians, the ancient Romans probably used "IIII" most of the time. This is partially backed up by the fact that early grandfather clocks displayed IIII for the number 4 instead of IV. Early clockmakers apparently thought that the IIII balanced out the VIII (used for the number 8) on the clock face and that it just looked better.

For a complete list of videos, visit our video library