Sheskin DJ (2004) Handbook of parametric and nonparametric statistical procedures.Parshall MB (2013) Unpacking the 2 x 2 table.Pagano M, Gauvreau K (2000) Principles of biostatistics.Kirkwood BR, Sterne JAC (2003) Essential medical statistics, 2 nd ed.Deeks JJ, Higgins JPT (2010) Statistical algorithms in Review Manager 5.Odds ratios should be avoided when events are common. Altman DG (1991) Practical statistics for medical research.

A standard normal deviate ( z-value) is calculated as ln(OR)/SE, and the P-value is the area of the normal distribution that falls outside ± z (see Values of the Normal distribution table). Test of significance: the P-value is calculated according to Sheskin, 2004 (p. Where zeros cause problems with computation of the odds ratio or its standard error, 0.5 is added to all cells (a, b, c, d) (Pagano & Gauvreau, 2000 Deeks & Higgins, 2010). Anne Segonds-Pichon, a Biostatistician, and one of the instructors on the Graphpad Statistics Bootcamp series demo. With the standard error of the log odds ratio being Graphpad Statistics Bootcamp As more and more funding bodies are asking for the actual power calculations and reviewers are using power, the importance of power analysis will only rise in importance. The odds ratio (OR), its standard error and 95% confidence interval are calculated according to Altman, 1991.

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