For example, we could find the IQ of every person in the United Kingdom, and then find the mean. This mean IQ would be a parameter> This particular parameter, the mean, is typically labelled

\[\mu\]

.To find the IQ of every person in the United Kingdom would take a lot of effort, money, contain errors and be very expensive. We can find a very good estimate of the average IQ in the UK by taking a suitable sample of people and finding the average IQ of that sample. The average IQ calculated in this way is called a statistic. This particular statistic, the mean is typically labelled

\[\bar{x}\]

.