representing data

• summary tables 


  • must be fully labelled
  • have a clear title that references the units of measurement, the numbers in the table and the conditions in the experiment
  • column headings
  • followed by a verbal summary of the table to describe what it shows
• bar chart


  • used to show frequencies in columns with the frequency on the vertical axis and the variable on the horizontal axis
  • when columns are drawn there is always a gap
• scattergram 


  • used for correlational data
  • one variable is plotted on each axis with each pair shown as a single cross/dot
  • the pattern of dots indicates a positive, negative or zero correlation
  • no line
• histogram 


  • similar to a bar chart but the area within the bars must be proportional to the frequencies represented
  • this means the vertical axis must begin at 0
  • the horizontal axis must be continuous
  • no gaps between bars
• distributions 


  • show us how scores are distributed in a data set
  • this is done by drawing the curve of the line around our histogram graph
  • we can have normal or skewed distributions
• normal distributions 


  • used to see how traits are distributed through a population
  • "bell curves" track rare occurrences of a trait on both the high and low ends of the curve with the majority of occurrences appearing in the middle section of the curve where it peaks
• skewed distribution


  • sometimes scores are not distributed equally around the mean
  • positively skewed distribution - most of the scores are distributed towards the left of the graph, the mean and median are greater than the mode
  • negatively skewed distribution - most of the scores are distributed to the right of the graph, the mean and median are less than the mode