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BIOL2608 Biometrics Computer lab session II. Testing for goodness of fit – Chi square test. Chi square goodness of fit. Infers whether a population conforms to a specified theoretical distribution from a sample of nominal scale data . Chi square goodness of fit.
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BIOL2608 BiometricsComputer lab session II Testing for goodness of fit – Chi square test
Chi square goodness of fit • Infers whether a population conforms to a specified theoretical distribution from a sample of nominal scale data
Chi square goodness of fit • H0: the sample data came from a population following a specified theoretical distribution • HA: the sample data came from a population NOT following a specified theoretical distribution • , ei = expected value, oi = observed value k = number of categories
Example • In a survey, 100 students were asked whether they have experience travelling to Europe. • 39 have travelled to Europe and 61 have not. • H0: The results were obtained by chance (expected frequencies: 50 travelled and 50 not travelled) • HA: The results were not obtained by chance
Example Probability that H0 is accepted. Can be checked from Chi table with calculated Chi Square.
Related Readings • Zar, J. H. (1999). Biostatistical Analysis, 4th edition. New Jersey: Prentice-Hall. • Chapter 22.1
Your demonstrators Kevin Ho kyho2@hku.hk Adela Li lijingecology@gmail.com Andy Yi yixianliang120@hotmail.com Edward Lau tclau36@hku.hk Vera Chan verabschan@gmail.com