Discrete and continuous

Quantitative variables are divided into ‘discrete’ and ‘continuous’. A discrete variable is one that can only take certain values, which are clearly separated from one another – for instance, a sales department can have 2 or 15 or 30 people within it. It cannot, however, contain 38 or 48.1 people. A continuous variable is one that could take any value in an interval. Examples of continuous variables include body mass, height, age, weight or temperature. Where continuous variables are concerned, whatever two values you mention, it is always possible to have more values (in the interval) between them. An example of this is height – a child may be 1.21 metres tall when measured on 27th September this year, and 1.27 metres on 27 September next year. In the intervening 12 months, however, the child will have been not just 1.22 or 1.23 or 1.24 and so on up to 1.27 metres, but will have been all the measurements possible, however small they might be, between 1.21 and 1.27.

Sometimes the distinction between discrete and continuous is less clear. An example of this is a person’s age, which could be discrete (the stated age at a particular time, 42 in 2007) or continuous, because there are many possible values between the age today (42 years, 7 weeks and 3 days) and the age next week (42 years, 8 weeks and 3 days).

5. Write out the definitions from the texts:

Variable (in everyday language);

Variable (in statistics);

Discrete variable;

Continuous variable;

Constant (in everyday language);

Constant (in statistics);

Attributes.

6. Complete the following sentences:

· In every day language variable….

· In statistical language variable is…..

· In every day language constant ….

· In statistical language constant is …..

· In statistical language, when your variables and constants are categorical…

· Quantitative variables are divided into…

· A discretevariable is…

· A continuous variable is ….

· Where continuous variables are concerned….

· Sometimes the distinction between discrete and….