Basically categorical variable yield data in the categories and numerical variables yield data in numerical form.
Numerical data can be either discrete or continuous.
The table below may help you see the differences between these two variables. 72 inches Notice that discrete data arise fom a counting process, while continuous data arise from a measuring process. There are several types of chi square tests depending on the way the data was collected and the hypothesis being tested. General notation for a 2 x 2 contingency table. Suppose you conducted a drug trial on a group of animals and you hypothesized that the animals receiving the drug would survive better than those that did not receive the drug.