Learning Lab

Definitions

\(\mathbf{Population}\): the total group of individuals or items under consideration.

\(\mathbf{Sample}\): a group of individuals or items chosen from the population.

\(\mathbf{Data}\): the information collected from the sample or population.

\(\mathbf{Statistic}\): a number calculated from the sample data.

\(\mathbf{Parameter}\): a number calculated from the population data.

Types of data

Data may be either qualitative (categorical) or quantitative (numerical)

\(\mathbf{Qualitative\,Data}\) (classified or labeled).

Data is put into non-numerical categories. Blood type, religion, cause of death, are all examples of qualitative data.

\(\mathbf{Quantitative\,Data}\) (counted or measured).

There are two types of quantitative data.

\(\mathit{Discrete\,Data:}\) data is put into categories depending on its counted number; for example, the number of children in a family.

\(\mathit{Continuous\,Data:}\) data is put into categories depending on its measured size; for example, height.

Graphical Representation of Data

Qualitative/Categorical data is often represented by means of a bar chart or a pie chart.

Quantitative/Numerical Data is often represented by means of a frequency bar chart called a histogram.

Exercise 1

Label each of the following as either a categorical or numerical variable. For the numerical variables label each as either discrete or continuous.

1. Hair colour

2. A persons religion

3. A persons height

4. Number of children in a family

5. The weights of babies born on a particular day

6. The number of crimes committed in Victoria each week

7. The distance traveled to work by the employees of a large company

8. The make of car driven by students at RMIT

Exercise 2

Represent the data in example 1 in a bar graph.

Exercise 3

A group of employees recorded the time that it took them to travel to work on a particular day (see table below). Represent this data using a histogram.