Statistical Skills: Mean, Median, Mode & Correlation — GCSE Geography Revision

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What is Statistical Skills: Mean, Median, Mode & Correlation?

Statistical skills are essential for analysing data collected during fieldwork and for interpreting graphs and charts. Key measures of central tendency include the mean (the average), the median (the middle value in a ranked list), and the mode (the most frequent value). Correlation describes the relationship between two variables; it can be positive (as one variable increases, so does the other), negative (as one increases, the other decreases), or have no correlation.

Board notes: Statistical skills are a core component of the geographical skills section for all boards (AQA, Edexcel, OCR). Students can be asked to calculate the mean, median, mode, range, and interquartile range, and to describe and interpret correlations shown on scatter graphs.

Worked example

Common mistakes

• 1Confusing the mean, median, and mode. The mean is sensitive to extreme outliers, whereas the median is often a better representation of the 'typical' value in a skewed dataset.
• 2Assuming that correlation proves causation. Just because two variables are correlated does not mean that one is causing the other to change. There may be a third, underlying factor influencing both. For example, ice cream sales and drownings are positively correlated, but the cause is the hot weather, not ice cream.
• 3Choosing the wrong type of graph for the data. Bar charts are for discrete categories, line graphs are for continuous data over time, and scatter graphs are for showing the relationship between two variables.

Statistical Skills: Mean, Median, Mode & Correlation exam questions

Exam-style questions for Statistical Skills: Mean, Median, Mode & Correlation with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel and OCR specifications.

Frequently asked questions

• When should I use the mean?

  The mean is useful for getting a quick average of a set of data, like the average score in a test. However, it can be misleading if there are very high or very low values (outliers) in the data set.

• What does a strong positive correlation look like on a scatter graph?

  On a scatter graph, a strong positive correlation is shown by the points being clustered closely together in a line that goes up from the bottom left to the top right. This indicates that as one variable increases, the other variable also consistently increases.