Chapter 2 - Processing and Representing Data

• Bar charts

  bars are equal width

  equal gaps between bars

  frequency on y-axis
• Pie charts

  area of pie chart = total frequency

  angles for each frequency = 360/frequency

  pie charts show proportion not numbers
• Comparative pie charts

  r2 = r1 x (square root of F2/square root of F1)
• Cumulative frequency diagrams

  running total of the frequencies

  use upper bounds for x-axis
• CF step polygons

  use for discrete data

  plot points using upper bound of class interval and join points using straight lines by going across then up
• CF curves

  used for group continuous data

  plot pints using upper bound of class interval and connect with a smooth curve
• Histograms

  represents continuous data from grouped frequency tables

  no gaps between bars

  unequal class widths use frequency density

  frequency = frequency density x class width
• Frequency polygons

  use mid points of class intervals and points are plotted then joined together with a straight line