STATS 2B03 Lecture Notes - Poisson Distribution, Contingency Table, Binomial Distribution
19 Jun 2013
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Chapter 12: the chi-square distribution and the analysis of frequencies. Appropriate when one wishes to decide if an observed distribution of frequencies is incompatible with some preconceived or hypothesized distribution. Expected and observed frequencies are compared, if the discrepancy is sufficiently small, the null hypothesis is tenable. The problem of small expected frequencies may be encountered when analyzing data of contingency tables. A simple sample is selected from a population of interest, and the subjects or objects are cross-classified on the basis of the two variables of interest. The rationale for calculating expected cell frequencies is based on the probability law, which states that if two events are independent, the probability of their joint occurrences is equal to the product of their individual probabilities. The hypotheses and conclusions are stated in terms of the independence of two variables. Two or more populations are identified in advance, and an independent sample is drawn from each.
