Categorical Data I (collecting and displaying)

Categorical data is data that is sorted by groups or categories. Often we look at categories people fit into, such as hair colour, eye colour or gender. However, it doesn't always involve people, types of dogs people own, colours of marbles in a jar or even whether a coin lands on heads on tails are also examples of categorical data.

Let's look now at how we can collect and display categorical data.

1) Decide What Information You're Going to Collect

This is also called a research question. For this example, I want to know what coloured marble is most common in this jar.

 

2) Construct a Frequency Table

Your frequency table should list all possible outcomes for the experiment you are running. What outcomes are possible in my experiment? Well, there are green, red and blue marbles in the jar- these are all the possible outcomes. My frequency table would look something like this:

Colour	Tally	Total
Red		7
Green		10
Blue		3

 

 

3) Create a graph to display your results

Remember different graphs are suited to different types of data. Bar graphs, column graphs, divided bar graphs or pie charts are good ways to display categorical data. Here is my data displayed in a pie chart.

Now we can clearly see that green is the most common colour of marble in the jar.

Worked Examples

Question 1

 

Question 2

 

Question 3