Pearson Chi Square Formula. It is used when categorical data from a sampling are being compared to expected or true results. χ 2 o i e i 2 e i.
If n is sufficiently large the above binomial distribution may be approximated by a gaussian normal distribution and thus the pearson test statistic approximates a chi squared distribution bin n p n n p n p 1 p. The chi squared test is done to check if there is any difference between the observed value and expected value. χ 2 o i e i 2 e i.
The pearson chi square statistic χ 2 involves the squared difference between the observed and the expected frequencies.
The formula for chi square can be written as. Displaystyle text bin n p approx text n np np 1 p. The pearson chi square statistic χ 2 involves the squared difference between the observed and the expected frequencies. Chi squared more properly known as pearson s chi square test is a means of statistically evaluating data.
