EEB225H1 Lecture Notes - Lecture 4: Odds Ratio, Contingency Table, Mosaic Plot
28 Apr 2016
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Two categorical variables; how frequencies of different values for one variable dependent on the value of another variable when both are categorical. Comparing death vs. survival among men and women during the titanic). Odds ratio: estimating association in 2x2 tables: measures the magnitude of association between two categorical variables when each variable has only two categories. Explanatory variable: has two categories: compares the proportion of successes and failures between two groups for example, odds: prob. of success=p and the prob of failure=1-p. If o=1 (odds 1:1), then one success occurs for every failure. If o=10 (10:1), then10 trials result in success for every one that results in failure. Estimate of odds calculated from random sample of trials using the observed proportion of successes: odds ratio: ratio of the odds of success between two groups. If o1 is the odds of success in one group, and o2 is the odds in the other group, then odds ratio is.
