Data Handling and Statistics
What the exam tests
Data handling and statistics tests collecting and organising data in tables, tally charts, pictograms and bar charts, and finding the mean, median, mode and range.
Core rules
- Frequency is the number of times a value occurs. A tally uses groups of five.
- In a pictogram, use the key to convert symbols to numbers. In a bar chart, read the scale carefully, including half-units.
- Mean = sum of all values ÷ number of values.
- Median = the middle value after the data are arranged in order. If there are two middle values, average them.
- Mode = the value that occurs most often. Range = largest value − smallest value.
- A table should have clear labels and a title.
Worked example
Find the mean, median, mode and range of 4, 7, 7, 9, 13. Sum = 4 + 7 + 7 + 9 + 13 = 40. Number of values = 5. Mean = 40 ÷ 5 = 8. In order, the median is the third value: 7. The mode is 7 because it appears twice. Range = 13 − 4 = 9.
Traps that cost marks
Do not find the median before ordering the data. Do not call the mean the middle number. The range is a difference, not a count of values. When reading a bar chart, check whether each square represents 1, 2, 5 or 10. Do not ignore a zero frequency in a table, and do not use the mode when the question asks for the mean.