Exercise Session 2

Questions.

1. The ‘T-Swift’ protein was quantified in the blood of the two groups. Women were found to have higher levels of the protein ( M = 1.062, SD = 0.339, N = 60) than men ( M = 0.528; SD = 0.382, N = 60). Calculate the raw difference effect size (D) and its variance + SE.

2. Calculate the Cohen’s d for the example above and its variance and SE. Calculate Hedges’ g and its SE.

3. Convert the Cohen’s d you calculated in step 3 to a Pearson r and its SE. The formula for SE is not provided on the slides but you can get it from Borenstein et al. (2009) chapter 7 (see here)

4. In a study you see the following table for and association between hay fever and eczema in 11 year old children.

What is the probability that a child with eczema will also have hay fever? (proportion and/or %). For children without eczema, what is the probability of having hay fever (proportion and/or %). What is the risk difference? Look up the formula for the SE of risk difference, here.

Calculate the Odds Ratio. The ln(OR) and its SE.

5. In a paper, you find a reported risk difference of 12% between men and women in ever having taken LSD. The authors did not report the SE or raw data but did provide the 95 confidence interval fo their estimate (8.2% to 15.8%). Work out the SE for this estimate, so you can use it in your meta-analysis (tip: use the Cochrane Handbook, alternatively use google).

6. Bonus : You are reading a paper on the effects of an Angiotensin-Converting–Enzyme Inhibitor, Ramipril, on Cardiovascular Events (simply put: heart attacks) in High-Risk Patients and come across some interesting stats. From the table below calculate the ‘Number Needed to Treat’. Calculate the 95% CI of NNT.