1.4 Types of Data

Qualitative data

Non-numerical (descriptive) data

Quantitative data

Numerical data

What two categories is quantitative data split up into?

• Discrete

• Continuous

Discrete data

Counted, can only take particular values, such as shoe size; there is no shoe size between 7 and 7.5.

Continuous data

Measured, can take any value within a given range. There are an infinite number of heights between 160cm and 161cm depending upon how accurately we choose to measure.

What is raw data?

Data that has been collected but not sorted

When are grouped frequency distributions used?

When a data set has too many categories for an ordinary frequency distribution

What is the formula for class width?

Class Width = (Largest value - smallest value)/Number of groups

How do you work out the boundaries of a class (class boundary)?

Find the lower and upper bounds

What are the class boundaries for a class of 45 - 46 of arbitrary data?

44.5 — 46.5

How do you work out the width of a class (class width)?

Upper bound - lower bound