chi-square

[ kahy-skwair ]

noun

, Statistics.

1. a quantity equal to the summation over all variables of the quotient of the square of the difference between the observed and expected values divided by the expected value of the variable.

chi-square

/ kī′skwâr′ /

1. A test statistic that is calculated as the sum of the squares of observed values minus expected values divided by the expected values.

Word History and Origins

Origin of chi-square¹

First recorded in 1935–40

Example Sentences

In addition, the study’s researchers used Chi-Square Automatic Interaction Detection tree models, a type of statistical analysis, to discover the relationship between history of depression, concussion, race, ethnicity and sex variables.

From Seattle Times

By repeatedly tallying whether or not a one-hour period following or not following your observation of a black cat in an area with high cat density did or did not bring you some specified level of misfortune, and by applying the statistician’s chi-square test, you can quickly convince yourself that the black-cat hypothesis has a probability of less than 1 out of 1,000 of being true.

From Salon

The probability used in the Chi-square formula is one-half of the percentage of all pairs compared in which the skulls were different in regard to the character being considered.

From Project Gutenberg

The significance of each difference reported was calculated by the Chi-square test and the confidence limit is given in each case.

From Project Gutenberg