54 Research methodology – 2
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| 1. Parametric statistics can be used if the distribution of results is Gaussian. |  |
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| 2. If standard deviations are larger, the effect size will be larger. |  |
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| 3. If p <0.05, there is a real difference between populations under study. |  |
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| 4. The standard error of the mean (SEM) is used in calculating confidence intervals for differences between means of continuous measures. |  |
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| 5. If multiple tests are performed without adjusting significance thresholds, then a type II error is more likely. |  |
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| 6. If a hypothesized difference between populations is small, fewer subjects are needed to make a study adequately powered. |  |
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| 7. Development of the randomized controlled trial means that other types of treatment studies with less rigorous methodology are obsolete and of no use. |  |
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| 8. Randomization ensures that treatment groups are similar on known and unknown variables. |  |
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| 9. Convergent validity is often measured by correlating overall scores on a new outcome scale with overall scores on an established scale. |  |
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| 10. The Ham-D is a good scale to use to diagnose depression. |  |
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| 11. Parametric tests use the difference in means and the standard deviation. |  |
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| 12. The Kruskal–Wallis Test is a non-parametric test that can be used to compare more than two unrelated groups. |  |
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| 13. The use of per protocol analysis is a good way to take into account differential dropout rates between treatment groups. |  |
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| 14. The use of intention-to-treat analysis is a way to deal with attrition bias. |  |
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| 15. The use of a placebo run-in may overestimate treatment effects. |  |
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| 16. In a case-control study, if an exposure of interest increases rates of hospital admission, there may be a Berkson bias. |  |
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| 17. In a case-control study of the association between the diagnosis of alcohol dependence and the diagnosis of depression, the relative risk is the statistic that would give the most useful information on strength of association. |  |
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| 18. If the lower boundary of the confidence interval for the odds ratio for lifetime cannabis use and schizophrenia is greater than 1, we can conclude that it is likely that there is a real association between cannabis use and schizophrenia. |  |
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| 19. In a case-control study, multiple linear regression can be used to prove that an exposure of interest causes an outcome of interest. |  |
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| 20. Multiple linear regression is an appropriate statistical technique to use if there is a curvilinear relationship between variables. |  |
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| 21. Before starting a screening programme, it is essential that there is a clear plan for what to do with cases screened as positive. |  |
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| 22. For a screening test for schizophrenia, positive predictive value will be higher for a random community sample than for a psychiatric inpatient sample. |
