Statistics & Data Handling — Year 7 Revision Notes
These notes cover organising data, drawing and reading charts, and calculating the averages and range of a data set.
Organising and displaying data
Data can be organised in a frequency table that records how often each value occurs. Pictograms use a symbol to represent a number of items, and bar charts use the height of bars. Always include a title and clear labels.
Tips
- On a pictogram, state what one symbol represents in the key.
- On a bar chart, leave equal gaps between bars and label both axes.
Averages: mean, median and mode
The mean is the total of all values divided by how many there are. The median is the middle value when the data is in order. The mode is the most common value. For 3, 5, 5, 8: the mean is 21 ÷ 4 = 5.25, the median is 5, and the mode is 5.
Key Facts & Formulas
- Mean = total of values ÷ number of values
- Median = middle value (data in order)
- Mode = most common value
Tips
- Always put the data in order before finding the median.
- If there are two middle values, the median is halfway between them.
Range
The range measures how spread out the data is: it is the largest value minus the smallest value. A small range means the data is close together. For 3, 5, 5, 8 the range is 8 − 3 = 5.
Key Facts & Formulas
- Range = largest value − smallest value
Tips
- The range is a measure of spread, not an average.
- A smaller range means more consistent data.
Revision Checklist
- I can organise data in a frequency table
- I can draw and read pictograms and bar charts
- I can calculate the mean, median and mode
- I can find the range of a data set
Frequently Asked Questions
Which average should I use?
It depends on the data. The mean uses every value, the median is useful when there are extreme values, and the mode is best for the most popular choice.
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