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9990 · 3.1.2

Research methodology — practice questions

Practice and worked examples for 9990 Research methodology. Short previews only — attempt the full question in MarkScheme against the official scheme.

Worked example 1

A researcher wants to test whether a text-message reminder system improves medication adherence in diabetic patients.

(a) Outline an experimental design for this study, identifying the IV, DV, and one control. [4 marks] (b) Identify one ethical issue and one validity issue with this design. [4 marks]

Show solution outline

(a) Experimental design:

  • Design: Independent groups — Group A receives SMS reminders; Group B receives no reminders (control).
  • IV: Reminder condition (reminders vs no reminders).
  • DV: Adherence rate — operationalised as pill count or biochemical marker (HbA1c as proxy for glucose control).
  • Control: Match groups on age, diabetes type, and baseline adherence; standardise medication regimen.

(b) Ethical issue:

  • Confidentiality — health data is sensitive; participants must consent to SMS contact and data storage under GDPR/medical ethics.

Validity issue:

  • Self-report adherence (if used) lacks validity due to social desirability — patients may overreport compliance. Biochemical measures improve objectivity but increase cost.

Additional evaluation: Field experiment has high ecological validity (real-world setting) but less control over extraneous variables (e.g. family support) than a lab study.

Worked example 2

A psychologist used a repeated measures design to test if a mindfulness app reduced anxiety. Participants (N=10) rated their anxiety on a scale of 1-40 before and after a 4-week intervention. A lower score indicates lower anxiety.

Data:

  • Before: [25, 30, 28, 35, 22, 19, 31, 26, 29, 24]
  • After: [20, 22, 28, 25, 24, 15, 23, 20, 21, 18]

(a) Using the Sign Test, calculate the observed value of S. [3 marks] (b) The critical value for a one-tailed test at p≤0.05 for N=9 is 1. State whether the result is significant and explain your conclusion. [2 marks]

Show solution outline

(a) Calculation of S:

Step 1: Find the direction of difference for each participant. Subtract the 'After' score from the 'Before' score. A positive result means anxiety decreased.

  • P1: 25 - 20 = +5 (+)
  • P2: 30 - 22 = +8 (+)
  • P3: 28 - 28 = 0 (ignore)
  • P4: 35 - 25 = +10 (+)
  • P5: 22 - 24 = -2 (-)
  • P6: 19 - 15 = +4 (+)
  • P7: 31 - 23 = +8 (+)
  • P8: 26 - 20 = +6 (+)
  • P9: 29 - 21 = +8 (+)
  • P10: 24 - 18 = +6 (+)

Step 2: Count the signs.

  • Number of positive signs (+) = 8
  • Number of negative signs (-) = 1
  • Number of zero differences = 1

Step 3: Determine the value of S. The observed value (S) is the count of the less frequent sign.

  • S = 1

(b) Conclusion:

Step 1: Compare the observed value to the critical value.

  • The total number of participants with a difference (N) is 10 - 1 = 9.
  • The observed value S = 1.
  • The critical value given is 1.

Step 2: State significance. For a result to be significant, the observed value (S) must be less than or equal to the critical value.

  • 1 ≤ 1. The result is significant.

Step 3: Write the conclusion. There is a significant reduction in anxiety scores after using the mindfulness app (S=1, N=9, p≤0.05, one-tailed test). This suggests the intervention was effective in reducing anxiety for this group of students.

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