INTERPRETING GRAPHS AND DIAGRAMS

(NB All the figures and outcomes are made up.)

Question 1 and 2 refer to the diagram below

The figure below is a L’Abbe plot displaying the result of 3 trials of diazepam for social phobia

  1. What is the NNT for study A
  1. 1
  2. 1.25
  3. 1.5
  4. 2.5
  5. Not possible to calculate from the information presented
  1. What is the significance of the fact that the circle for study C crosses the diagonal line
  1. The result is statistically significant
  2. The result is statistically insignificant
  3. The confidence interval is the largest of the three studies
  4. Treatment is harmful
  5. None
  1. All of the following could be featured on the y axis of a funnel plot EXCEPT
  1. Standard Error
  2. 1/se
  3. Sample size
  4. Log sample size
  5. Effect size
  1. Funnel plots are analysed via
  1. Bellow’s test
  2. Egger’s test
  3. Roth’s test
  4. Mailer’s test
  5. Updike’s test

+ An extra bonus smartarse point if you know what links all 5 answersand my deliberate mistake

  1. The funnel plots above tabulate the same 5 RCTs of the effect of diazepam in the treatment of performance anxiety, with 2N on the y axis on the left and 1/se on the right. Taken in concert their appearances could be plausibly attributed to all of the following EXCEPT
  1. Selection bias in some studies
  2. Publication bias
  3. Clinical Heterogeneity
  4. Statistical heterogeneity
  5. Methodological heterogeneity

Questions 6 to 11 refer to the Forest plot below of 5 placebo controlled studies of Moclobemide in social phobia.

  1. Standardised mean difference is standardised to what?
  1. Expert consensus
  2. Expected effect size based on previous work
  3. Standard deviation of the study
  4. The International reference unit of shyness that Morrissey keeps in a vault in his bedroom
  5. The level of shyness in the US population in 1940
  1. Where is the line of equivalence in the diagram?
  1. -2
  2. -1
  3. 0
  4. 1
  5. 2
  1. Which study has been rated as most reliable
  1. Regarding study A; taking the point estimate of effect size what proportion of subjects receiving IPT improved more than the mean of the control group?
  1. None
  2. Most
  3. 50%
  4. 84%
  5. 95%
  1. What kind of heterogeneity is being tested for?
  1. Behavioural
  2. Clinical
  3. Methodological
  4. Sample size
  5. Statistical
  1. Statistical heterogeneity is present as indicated by
  1. P value < 0.05 for chi squared test
  2. 3 studies show no effect
  3. Discrepancy of CI for fixed and random effect analyses
  4. Differing weights
  5. Smaller studies having wider confidence intervals

Questions 12 to 15 refer to the diagram below

The diagram shows a Kaplan Meier Curve plotting time to first relapse for a sample of 20 patients with schizophrenia following discharge from hospital.

  1. What are the little hatched lines in the horizontal lines
  1. Significance levels
  2. Relapsing patients
  3. Confidence intervals
  4. Censored values
  5. Centiles
  1. ‘Censored’ values would include
  1. Patients who left the area and were no loner available for follow up
  2. Patients who had a relapse
  3. Patients who refused consent prior to study onset
  4. Patients who relapsed after the end of the study
  5. All of the above
  1. What is the median survival time to relapse?
  1. 100 days
  2. 180 days
  3. 300 days
  4. 360 days
  5. Impossible to assess without complete follow up data
  1. If a patient survived without relapse for 100 days, what would be the probability of their surviving a further 100 days? (as in all the best exams you only get full marks if you show your working)
  1. 1
  2. 0.9
  3. 0.8
  4. 0.77
  5. 0.7