Welcome to this deck on numerical and statistical skills for GCSE Geography. Being able to work with numbers is essential for understanding geographical data, from analysing climate figures to interpreting fieldwork results. We'll cover how to calculate averages and measures of spread, how to use percentages, and the basics of sampling and statistical testing. Mastering these skills is vital for success in your exams, especially for Paper 3.

Let's start with the basics: measures of central tendency. This is a technical term for different types of average. There are three you need to know: the mean, the median, and the mode. They each give us a typical value for a set of data, but they do it in slightly different ways.

First up is the mean. This is the most common type of average. To calculate the mean, you add up all the values in your data set, and then divide by the number of values you have. For example, to find the mean rainfall for a week, you would add up the rainfall for all seven days and then divide by seven.

Next is the median. The median is simply the middle value in a data set. To find it, you must first arrange all your data in numerical order, from smallest to largest. The number that sits exactly in the middle is the median. If you have an even number of values, the median is the mean of the two middle values.