Reference no: EM131339558

Review each of the cases below, and then in a minimum of 200 words per case, identify the following for each case:

 1. Did the case utilize a randomized or non-randomized experiment? Explain.

 2. What design was used in the study? Please choose from the following list:

• Within subject designs
• Factorial designs
• Between subject designs
• Time series design
• Interrupted time series design
• Single case experimental research design?

3. What threats to internal validity, if any, are present? Explain.

 4. In the example, was there a third variable problem? If so, define the third variable problem in the specific case.

 5. Did the case use longitudinal or cross-sectional research?

Case 1: Dr. Watts is studying the effects of cognitive-behavioral therapy on depression in battered women. He recruits 100 women for his study from the community by placing an ad in the local newspaper. The women are randomly assigned to one of two groups; one group receives treatment with cognitive-behavioral therapy, and the second group does not receive therapy. Twenty women withdraw from the study before it has concluded.

Case 2: Mavis is interested with how children develop play strategies at different points throughout early childhood development. She designs a research study that looks at 30 children over a period of five years. The children were recruited from a local daycare where Mavis works. Children were assigned to one of three groups based on age: Group 1 (age 6 months-12 months), Group 2 (age 12 months 1 day-24 months), and Group 3 (age 24 months-36 months). The children were observed during recess every six months for a five year period.

Case 3: Dr. Little designs a research study that looks at the effects of a new antipsychotic medication on individuals diagnosed with Schizophrenia. He recruits 500 participants for his study from seven local mental health outpatient programs. He assigns participants to one of two groups: Group A (treated with new medication) or Group B (treated with an existing medication). Participants are assigned to one of the groups by randomly selecting a number from a box. Odd numbers were placed in Group A, and even numbers were placed in Group B.

Case 4: Mary wants to understand how women experience childbirth. She decides to speak with one woman at a local hospital maternity unit who has agreed to an interview. Mary uses a semi-structured interview to gather information from the woman about her delivery experience.