Proportions

The proportions of values in the categories (also called the relative frequencies of the categories) are the frequencies divided by the total number of values.

Percentages

The proportions are often expressed as percentages — simply the proportions multiplied by 100. For example, a proportion of 0.034 is more concisely expressed as 3.4% but contains identical information. It is usually easier to quickly compare a column of percentages than the corresponding column of proportions.

Percentages are usually easier to interpret than the raw frequencies, so frequency tables are often augmented with an extra column of percentages.

Kestrel causes of death

The frequency table below shows the causes of death of kestrels (a bird of prey) in Britain between 1963 and 1997. (Carcasses were sent to the researchers in response to advertisements in bird-watching magazines and journals and the cause of death was found from information sent by the finder and examination of the carcass.)

Choose the option Count & proportion under the frequency table to see the proportion of kestrels dying from each cause.

Finally, choose the option Count & percentage to express the proportions as percentages. Although the percentages are simply 100 times the corresponding proportions, the information in the data stands out better when percentages are used.