Lesson 1.4 Data

Data

As we learned in the Key Terms section, data are the actual values of variables. They may come from a population or from a sample.

There are two kinds of data, qualitative and quantitative.

Qualitative Data

Qualitative data can be described in words or symbols rather than in numbers; for example, we could collect qualitative data about our classmates' hair colors. We might find black, brown, blonde, red, and even some purple! We could also collect qualitative data about blood types. Examples of blood types are O+ and AB-.

The important idea is that we are concerned with the qualities (hair color) rather than the numbers (how many people have those hair colors). Qualitative data may also be called categorical data.

(blonde, black, purple, brown, red hair)

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Quantitative Data

Quantitative data is described by numbers, in contrast to qualitative data, which is described in words. Quantitative data can be divided into two categories: discrete data and continuous data (see below).

Discrete Data

Discrete data are quantitative data that are counted. The number of shoes that you own is an example of discrete data. This is because you can count the number of pairs (in the picture below, 2 pairs).

(2 pairs of shoes)

Continuous Data

Continuous data are quantitative data that are measured. For example, the speed of a car is something that can be measured (by the car's speedometer or a police officer's speed gun!). The car below is travelling at high speed, measured at 75 miles per hour (mph).

Variations in Data

Variations in data occur quite naturally. For example, an advertised 8-ounce cup of coffee served in a restaurant might have from 7.9 to 8.1 ounces of coffee.

(7.9 - 8.1 ounces)

Please continue to the next section of this lesson.

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