OpenRevise

Maths · Statistics

Knowledge organiser

The whole chapter on one page. Print it on A4 — it is already landscape — or cover a box and see how much of it you can say from memory.

Back to the chapter

Maths · Edexcel Paper 2

Statistics

Averages and Range

Finding the mean, median, mode and range, using frequency tables and grouped data, and choosing the best average.

  • Mean The sum of the values divided by how many there are.
  • Median The middle value when the data is in order.
  • Mode The value that occurs most often.
A dot plot of ten values showing a mean and median of 5, a mode of 6 and a range of 8.

Pie Charts, Bar Charts and Stem-and-Leaf Diagrams

Drawing and reading pie charts, bar charts and stem-and-leaf diagrams, and spotting misleading charts.

  • Pie chart A circular chart where the angle of each sector represents its share of the total.
  • Sector A slice of a pie chart.
  • Bar chart A chart that uses bars of different heights to show frequencies.
A pie chart of the favourite sports of 60 students with the angle and frequency shown for each sector.

Scatter Graphs

Describing correlation, using lines of best fit to estimate, and judging how reliable an estimate is.

  • Scatter graph A graph of plotted points showing how two variables are related.
  • Correlation The relationship between two variables.
  • Positive correlation Both variables increase together.
A scatter graph of revision time and test score showing positive correlation, a line of best fit and one outlier.

Cumulative Frequency and Box Plots (Higher tier)

Drawing and reading cumulative frequency graphs, finding quartiles, and comparing distributions with box plots.

  • Cumulative frequency The running total of the frequencies.
  • Quartile A value that divides the ordered data into four equal parts.
  • Lower quartile The value a quarter of the way through the ordered data.
A cumulative frequency curve for 100 test marks with the lower quartile at 40, the median at 60 and the upper quartile at 70 marked with dashed lines.

Histograms and Sampling

Using frequency density to draw and read histograms, and taking random, stratified and capture-recapture samples.

  • Histogram A chart with touching bars where the area of each bar shows the frequency.
  • Frequency density Frequency divided by class width, used as the height of a histogram bar.
  • Class width The size of a class, found by subtracting its lower boundary from its upper boundary.
A histogram with four bars of different widths showing frequencies of 15, 60, 40 and 30 as the areas of the bars.