53 Research methodology – 1
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| 1. For a skewed distribution, the median is a more useful measure of central tendency than the mean. |  |
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| 2. When comparing recovery rates between two samples, parametric statistics are best. |  |
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| 3. For two studies with identical effect sizes, the p value will be smaller for the study with much larger numbers. |  |
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| 4. If the confidence interval for the difference in Ham-D scores between treatment groups includes 0, we can conclude that it is likely that there is a real difference between treatments that is not due to chance. |  |
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| 5. A type I error means that a result is falsely found to be statistically significant. |  |
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| 6. A very low p value indicates that a result is clinically significant. |  |
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| 7. An effectiveness study for a treatment for depression is more likely to include patients with co-morbid conditions than an efficacy study. |  |
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| 8. The need for informed consent can limit the external validity of treatment studies. |  |
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| 9. A scale must have good reliability for it to have good validity. |  |
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| 10. We should assess the criterion validity of new scales that measure depressive symptoms. |  |
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| 11. Log transformation is sometimes essential before parametric statistical tests are used. |  |
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| 12. Non-parametric tests use the difference in medians and the inter-quartile range. |  |
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| 13. Not taking into account dropouts from treatment may introduce bias. |  |
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| 14. The use of intention to treat analysis may reduce accuracy of results. |  |
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| 15. Subjects in cluster randomized controlled trials (RCTs) are analysed in exactly the same way as in standard RCTs. |  |
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| 16. Crossover studies can have more power than using different patients in different treatment groups. |  |
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| 17. Stratification can be used to control for confounding in a case-control study. |  |
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| 18. The t-test is commonly used to look at strength of association in case-control studies with a dichotomous exposure of interest. |  |
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| 19. Multiple logistic regression is used to investigate the effects of variables on a continuous outcome measure. |  |
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| 20. In multiple linear regression, if two covariates are highly correlated, there may be a type II error. |  |
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| 21. Multiple linear regression cannot be used if there is a heavily skewed distribution of a proposed variable. |  |
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| 22. For a screening test for schizophrenia, sensitivity will probably be lower for a random community sample than for a psychiatric inpatient sample. |  |
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| 23. A meta-analysis will give more accurate and less biased results than one RCT. |
