What is the study design used in the following research project? ...

[future617RT]

What is the study design used in the following research project?
 
  Twenty patients, all of whom have bipolar mania, have been placed on lithium and also begun on a medication believed to prevent rapid cycling. The patients are followed for 12 months, at which time they are seen by a psychiatrist monthly, to adjust their dosages. Medication compliance, emergency department visits, and mental health hospitalizations are measured. These are compared with another group of patients with the same mental illness, being treated on lithium alone.
  a. Posttest-only design with comparison group
  b. Pretest-posttest design with comparison group
  c. Pretest-posttest design with removed treatment
  d. Pretest-posttest design with two comparison treatments

Question 2

A group of twenty-five Labrador retrievers and their owners, are brought to the research lab one by one.
 
  The Labrador retrievers are shown various stimuli, including a squirrel that runs along a wire at the top of the lab, to elicit barking. Then the owners command the dogs to stop barking, and the stimulus is repeated. The duration of barking is measured. Then the owners are taught a different technique for quieting their barking dogs. A week later, the dogs and their owners return to the lab, the stimuli are introduced, and the duration of barking is measured. This is an example of what type of design?
  a. One-group posttest-only design
  b. One-group pretest-posttest design
  c. Pretest and posttest design with comparison group
  d. Pretest and posttest design with removed-treatment

[kilada]

Answer to Question 1

ANS: A
The posttest-only design with comparison group offers an improvement on the one-group posttest-only design, because of the addition of a nonequivalent comparison group. However, subjects are tested only after the treatment; the group is not pretested, so there is no direct way to measure change. In the example given, there is no mention of pretesting. In the pretest and posttest design with a comparison group, both the experimental group and the comparison group are tested both before and after the experimental group is treated. The pretest and posttest design with removed-treatment creates conditions that approximate the conceptual requirements of a control group receiving no treatment. The design is basically a one-group pretest-posttest design. However, after a delay, a third measure of the dependent variable is taken, followed by an interval in which the treatment is removed, followed by a fourth measure of the dependent variable. Pretest-posttest design with two comparison treatments are used when two experimental treatments are being compared to determine which is most effective. In most cases, this design is used when one treatment is the currently identified treatment of choice and the researcher has identified a treatment that might lead to even better outcomes.

Answer to Question 2

ANS: B
The one-group posttest-only design is referred to as pre-experimental rather than quasi-experimental because of its weaknesses and the numerous threats to validity. In this type of study, subjects are only tested after the treatment; the group is not pretested therefore, there is no direct way to measure change. The one-group pretest-posttest design, is one of the more commonly used designs; in it there is an experimental group that undergoes some form of pretesting prior to treatment (the manipulation of the independent variable) and then is subjected to posttesting after the treatment. In the pretest and posttest design with a comparison group, both the experimental group and the comparison group are tested before the experimental group is treated and after it. The pretest and posttest design with removed-treatment, even though it uses only one group, creates conditions that approximate the conceptual requirements of a control group receiving no treatment. The design is basically a one-group pretest-posttest design. However, after a delay, a third measure of the dependent variable is taken, followed by an interval in which the treatment is removed, followed by a fourth measure of the dependent variable.