Paul Garthwaite's Presentation on Statistics

1. MCT Mathematics & Statistics Paul Garthwaite [email_address] http://statistics.open.ac.uk/advisory.html Introduction to Statistical Analysis

3. Theory: In a pig’s digestive system, all phosphate ions are the same, regardless of what they were bound with. Theory: If you are a diabetic, losing weight will help you live longer.

4. Study Design (deductive reasoning)

5. Hypothesis testing is like a court of law: You aim to disprove the null hypothesis. The hypothesis of a court: The person in the dock is innocent. The aim is to gather evidence that is inconsistent with this hypothesis. We reject the hypothesis (and decide the person is guilty) if the evidence makes the hypothesis unlikely (beyond all reasonable doubt) .

7. Observational Study (inductive reasoning)

8. Observational studies could feed into inductive reasoning. Pilot studies have a place in forming hypotheses. Some disciplines (e.g. psychology) seem to disapprove of observational studies. Presumably such studies are written up as if the hypotheses were decided before gathering the data. (A dangerous practice!)

15. Questionnaires Likert scales are good: strongly weakly indifferent/ disagree/ strongly agree/ agree/ disagree. Having five points on a Likert scale is often about right. Code the values as 1, 2, 3, 4, 5 and it is usually OK to treat them as measurements. Open-ended questions are hard to analyse.