What is an example of interval data?

An example of interval data is temperature measured in degrees Celsius.

Interval data is a type of quantitative data where the difference between values is meaningful. This means you can add and subtract values, and the intervals between them are consistent. For instance, the difference between 20°C and 30°C is the same as the difference between 30°C and 40°C, which is 10 degrees in both cases.

However, interval data does not have a true zero point. In the case of temperature in degrees Celsius, 0°C does not mean the absence of temperature; it is simply a point on the scale. This is different from ratio data, where a true zero point indicates the absence of the quantity being measured, like 0 kilograms meaning no weight.

Understanding interval data is important because it allows for a wide range of statistical analyses. You can calculate the mean and standard deviation, and perform various other statistical tests. However, you cannot multiply or divide interval data in a meaningful way because there is no true zero. For example, saying that 20°C is twice as hot as 10°C doesn't make sense in the same way it would for ratio data.

In summary, temperature in degrees Celsius is a classic example of interval data, characterised by meaningful differences between values but lacking a true zero point.