Graphical representations

• Linear representations of data

  Include a mean, median and modal score to show a spread of data
• Positive skew

  A type of skewed distribution, where the mode is less than the mean
• Normal distribution


  A type of distribution where the mean, median and mode are equal (bell curve)
• Negative skew


  A type of skewed distribution, where the mode is greater than the mean
• Distribution curves

  • Positive skew
  • Symmetrical
  • Negative skew
• Frequency table

  A chart/table that shows the rate of occurrence (frequency) for a number of measured values/categories
• Line graph


  A diagram that shows a linear representation of frequencies of data. Scores are plotted and joined one by one with straight lines
• Scatter diagram


  A diagram that represents a relationship/correlation between two or more co-variables. It does not need to include a line of best fit
• Strongest negative correlation is r = -1.0
• Strongest positive correlation is r = +1.0
• Pie chart

  A diagram that represents data proportionately, as part of a whole picture of responses. Needs a key to explain segment labelling/shading
• Bar chart

  A diagram that represents frequencies of non-continuous (discrete) data. There should be gaps between all bars, and a gap between the first bar and legend/y-axis
• Histogram

  A diagram that represents the distribution of frequencies for continuous data. There should be NO GAPS between bars
• You should always include: 1) a title for the table/chart/graph/curve, 2) a key/legend where there are multiple types of data being displayed, 3) an appropriate scale for bar charts, histograms, line graphs and scatter diagrams, and 4) labels of your axes (where appropriate). Use a ruler and don't forget your protractor.