What’s A Chi-Square Test?
The Chi-Square Test is a hypothesis test that determines whether a statistically significant difference (aka variance) exists between two or more independent groups of discrete data, ruling out chance. It is useful for determining whether or not improvement implementations have been successful.
This test is performed on count data from different samples. An example would be: Assembly Line A produced 462 good parts and 265 defective parts whereas Assembly Line B produced 538 good parts and 321 defectives and you want to determine if Line A is truly better or the difference is just due to random chance.