STATISTICS AND EPIDEMIOLOGY ASSIGNMENTS-

1. Outline (using a numbered list) the ethical issues that should be considered when setting up a prevalence study within dentistry. How would you address them?

What is a double-blind study? When and why is it preferable for studies to be double-blind?

2. State, with examples, how you would assess whether new diagnostic tests are reliable in terms of precision and accuracy.

3. A researcher claims that among 10 year old children in a particular city a higher proportion of boys have cavities than girls. Explain how you would assess this, writing down the appropriate hypotheses, explaining what statistical test you would apply, how you would summarize the observations and how you would interpret the results of such a test. How would the size of your sample tend to affect the results?

4. What do you understand by the following statistical and epidemiological terms? You may find it helpful to use examples to illustrate your explanations.

a) retrospective study

b) post-hoc test

c) specificity

d) cohort study

e) histogram

f) log transformation

5. Explain with examples what is meant by null and alternative hypotheses and how they are used in statistical testing? Suppose that you conducted an independent samples t-test and the analysis resulted in a p value of 0.15. What does this value mean and what conclusions would you draw? What does a p value of 0.01 mean and what conclusions would you draw?

How does sample size tend to affect the results of a statistical test?

6. Explain briefly the principles behind, and the use and limitations of three of the following. Suggest situations where they might be used when analyzing dental data.

a) Wilcoxon matched-pairs signed-ranks test

b) Logistic regression

c) Paired t-test

d) 95% Confidence Interval