# Y9. Data. Calculating Statistics

A statistic is a single number that is used to represent a dataset.

The single most important statistic to represent a dataset is an average, which can also be called a measure of location or a measure of central tendency.

There are three averages that we will calculate – each of them we need to be able to calculate either for raw data or data compiled in a frequency table. The method is quite different in each case.

The second most important statistic we might calculate is a measure of dispersion or measure of spread. At this stage the only such measure we will consider is the range, which is simply the largest value in the data set minus the smallest value in the dataset.

Let’s find each of our three different averages and the range for the following raw data:

Now let’s find each of our three different averages and the range for the following data compiled in a frequency table:

Exercise

Let’s complete all of exercise 6E, questions 1 and 3 of exercise 6G and all of exercise 6H. These questions are on pages 84 to 88 of the textbook: