4 Making sense of data

4.7 Proportion

We can use a number of different ways to indicate change – fractions, decimals, and percentages tend to be the ones with which many of us are familiar.

Activity 11

Which of these represents the greater proportion:

10 per cent of 1260 or 140 out of 1260?

139 out of 1500 or 75 out of 250?

Discussion

or about 11 per cent, so this is the greater proportion. Alternatively, 10 per cent of 1260 is 126, which is less than 140.

139 is clearly the greater actual value. However, 139 out of 1500 is equivalent to × 100 = 9.27% of 1500.75 out of 250 is equivalent to × 100 = 30% of 250. Therefore, 75 out of 250 is a greater proportion than 130 out of 1500.

The phrase ‘proportional representation’ (PR) is used when we talk about systems of electing MPs or local councillors. This means that election results are according to the number of votes that people place for a party, rather than an individual. Once the votes have been counted for the party, then the MPs or councillors are elected according to their agreed position on a party list. In the UK, at the time of writing, we have a ‘first past the post’ system for local and national elections, but PR for the elections to the European Parliament, Scottish Parliament, Welsh Assembly and for elections in Northern Ireland. This brings the UK more into line with many other European countries.