What is a Chi-Square Test and How Does it Work?

"Science is advanced by proposing and testing a hypothesis, not by declaring questions unsolvable" – Nick Matzke Let's start with a case study. I want you to think of your favorite restaurant right now. Let's say you can predict a certain number of people arriving for lunch five days a week. At the end of the week, you observe that the expected footfall was different from the actual footfall. Sounds like a prime statistics problem?