Chi‐Square Test
Joseph S. Rossi · The Corsini Encyclopedia of Psychology · 2010
Abstract The chi‐square (χ 2 ) test was developed by Karl Pearson in 1900; this is often regarded as a seminal event in the history of statistics. The test and the statistical distribution on which it is based have wide application not only in psychology and the behavioral sciences but also in numerous related disciplines. Its two principal uses are to test the independence of two variables and to assess how well a theoretical model or set of a priori probabilities fits a set of data (goodness of fit). In both cases the test is typically thought of as a nonparametric procedure involving observed ( O ) and expected ( E ) frequencies. The expected frequencies may be determined either theoretically or empirically. The basic formula for calculating χ 2 is urn:x-wiley:9780470479216:media:corpsy0174:xm1