Frequency Distributions and Statistical Graphs

• a frequency distribution is a listing of observed values and the corresponding frequency of each value.
• When the data is distributed over a wide range, we form classes for the frequency distribution.
  • The classes should be the same width
  • The classes should not overlap.
  • Each piece of data should fit into exactly one class.
• For this course:
  • The class width is the number of integral values which fit into a class.
  • The lower class limit is the first number.
  • The upper class limit is the second number.
  • The width = upper class limit - lower class limit + 1
  • The class mark is (upper limit + lower limit)/2
• Histograms (bar charts) and frequency polygons
• Circle (or pie) charts
• Stem and leaf displays