AP Psychology · Free-response skill

Article analysis: a study of a sleep-habits program

The move. From one summarized treatment-outcome study, name its design and ethical safeguard, read the result with numbers, judge how far it generalizes, and say what the design lets you conclude.

How to do it

  1. Read the summary once for the story. Then mark the design clues, the groups, the exact measure, the protections for participants and every number in the results.
  2. For the design, name it and give the clue. Random assignment to a treatment group and a comparison group makes it an experiment, and random assignment is what lets you talk about cause.
  3. For a safeguard, name the step the summary describes, such as informed consent, and say what harm it prevents.
  4. To read the result, give each group's numbers before and after, and say which group changed more.
  5. To judge how far results reach, name who took part and who was left out, such as other ages, places or people with more severe symptoms.

Practice prompt Try it

Study summary (fictional). Researchers tested whether a 6-week group program that teaches sleep habits lowers symptoms of low mood. Participants were 90 adults, aged 30 to 60, with mild to moderate low mood, recruited at three community clinics. Each adult agreed in writing to take part after being told what the study involved. The adults were randomly assigned to the sleep-habits program (45 adults) or to a comparison group that received printed health tips (45 adults). Low mood was measured with a 10-item scale, each item rated from 0 to 3, for a total from 0 to 30, where a higher score means lower mood. Adults filled it out before and after the 6 weeks. The program group's average fell from 18 to 11, and the printed-tips group's average fell from 18 to 16. The difference between the groups was statistically significant.

Using the study summary, respond to each part.

  1. Name the kind of study this is, and give the detail from the summary that shows it.
  2. Say exactly how the researchers measured low mood.
  3. Name the step the summary describes for protecting the adults, and say what it protected them from.
  4. Give each group's average low-mood score before and after the 6 weeks, and say which group's score fell more.
  5. Give one reason the results might not hold for everyone with low mood, using a detail about who took part.
  6. Say whether the results support the claim that the program caused the larger drop in low-mood scores. Then explain how the way the adults were put into the two groups supports your answer.

Write each part, then check yourself against the checklist. Nothing you type here is saved or graded.

Check yourself and see a model answer

Checklist

Our own checklist of what a full answer does, one line per point. Tick each one your response earns.

0 of 8 points

Model answer, annotated

(a) This is an experiment. The researchers randomly assigned the adults either to the sleep-habits program or to a comparison group that got printed health tips.

  • Point 1 Names the design and gives the clue straight from the summary: random assignment to two groups.

(b) Low mood was each adult's total score on a 10-item scale, with each item rated from 0 to 3, for a total from 0 to 30, where a higher score means lower mood.

  • Point 2 Gives the exact measure and its 0-to-30 range, not a vague idea like how sad the adults seemed.

(c) Each adult agreed in writing to take part after being told what the study involved, which is informed consent. This protected the adults from being in a study without knowing what it involved or without agreeing to it.

  • Point 3 Names the safeguard the summary describes: written agreement after being told what the study involved.
  • Point 4 Says exactly what harm the step prevents: taking part without knowing or agreeing.

(d) The program group's average fell from 18 to 11, a drop of 7 points. The printed-tips group's average fell from 18 to 16, a drop of 2 points. The program group's score fell more.

  • Point 5 Gives all four averages and states which group's score fell more.

(e) All the adults were 30 to 60 years old and had only mild to moderate low mood, so the results might not hold for teenagers, adults over 60 or people with severe depression.

  • Point 6 Uses specific sample details, the age range and the symptom level, and names who was left out.

(f) Yes, the results support the claim that the program caused the larger drop. The adults were randomly assigned to the two groups, so the groups should have been alike on average at the start, and the program is the likely cause of the difference in how much their scores fell.

  • Point 7 Gives a clear judgment that the results support the program causing the larger drop.
  • Point 8 Says the adults were randomly assigned and that this made the groups alike at the start, so the program is the likely cause.