Thirty patients with psoriasis are treated with ultraviolet light ...

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Thirty patients with psoriasis are treated with ultraviolet light B phototherapy, delivered by a therapist. Their symptoms become worse at first, and then improve.
 
  During the summer their symptoms become better without treatment. Then fall arrives, and symptoms worsen. Patients go back to UVL B, and they improve. Why, according to Hume, can the relationship between UVL B phototherapy and symptom severity not be considered a classically causal one?
  a. Ultraviolet light B phototherapy wasn't invented during Hume's lifetime.
  b. There must be a strong relationship between the proposed cause and the effect.
  c. The cause (phototherapy) has to be present whenever the effect occurs.
  d. The cause must precede the effect in time.

Question 2

Why is selection of an appropriate design for a research study important?
 
  a. If the design is an incorrect one, the researcher will examine variables and their interactions in a way that does not answer the research question.
  b. The design provides a blueprint or diagram that appears in the concept map.
  c. If there is no design, critique is impossible.
  d. If the design is appropriate, the researcher can eliminate error.

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Answer to Question 1

ANS: C
Some of the ideas related to causation emerged from the logical positivist philosophical tradition. Hume, a positivist, proposed that the following three conditions must be met to establish causality: (1) there must be a strong relationship between the proposed cause and the effect, (2) the proposed cause must precede the effect in time, and (3) the cause has to be present whenever the effect occurs. Cause, according to Hume, is not directly observable but must be inferred.

Answer to Question 2

ANS: A
A research design is the blueprint for conducting a study. It maximizes control over factors that could interfere with the validity of the study findings. Being able to identify the study design and to evaluate design flaws that might threaten the validity of findings is an important part of critically appraising studies. When conducting a study, the research design guides the researcher in planning and implementing a study in a way to achieve accurate results. The control achieved through the quantitative study design increases the probability that the study findings are an accurate reflection of reality.