Concepts and Definitions

Percentages are one of the most commonly used statistics. They can be found in rates (e.g. unemployment rate, employment rate) and discounts in shop windows. So what is per cent? “Per cent” means “out of every 100”. Percentage figures are derived by dividing one quantity by another with the latter rebased to 100. Percentages are symbolised by %.

Besides being especially useful when making comparisons, they come in handy for studying a difference compared with a benchmark or initial value. Say we want to compare the increase in workers over the year in two cafés – the first, a single-branched café with 10 workers and the other, a chain of cafés with 100 workers. Over the year, both employed 2 more workers (net increase). Will it be fair to conclude that both cafés experienced the same expansion? Maybe not; we can use percentages to even the scores. Using percentages, the single-branched café grew by 20% while the chain’s growth was 2%.


How to Calculate Percentages

In general, to compute a value (value 1) as a percentage of another (value 2) we use the following formula: