A two-way table in statistics is a way to summarize data of two categories in compact tabular form. The advantage of a two-way table is that the data becomes much easier to understand when it is displayed in this form. Let us understand this by considering the following example.
Example: In a particular group of 100 people there are 50 males and 50 females. 15 males have a black eye colour whereas the remaining are blue eyed. 20 females are black eyed whereas the remaining are blue eyed. Represent this data in the form of a two-way table.
Solution: Since 15 males are black eyed, the remaining 35 are blue eyed. Similarly, since 20 females are black eyed the remaining 30 are blue eyed. We represent this as follows,
As we see in the above example, a two-way table consists of information about the joint frequencies of two categories. The two categories are gender and eye colour in the above example. One of the categories is represented in rows and the other in columns.
Advantages of a two-way table:
- We can use the two way table to construct the joint relative frequency table.
- We can find the marginal and conditional frequencies using the two way table.
- The two way table makes bivariate data very easy to grasp.