Pie Chart



Histogram with Normal Curve

Frequency Polygon

Shapes of Distributions

  • Frequency distributions: represent the number of scores that occur at certain values of a variable.
  • Distributions can take on a number of shapes or forms.

Unimodal Distributions

  • The mode: most frequently occurring score.
  • A unimodal distribution has one mode.

Multimodal Distributions

  • Multimodal distributions: more than one mode
  • Bimodal distribution: two modes

Rectangular or Uniform Distributions

  • Uniform distribution: all values are observed equally often

Symmetrical Distributions

  • A symmetrical distribution: if cut in half, the two sides would be mirror images of one another
  • Normal Distribution: a particular kind of distribution that resembles a bell (bell-shaped curve)

Skewed Distributions

  • A skewed distribution is not symmetrical. It is unbalanced


negative skew (skewed to the left)
positive skew (skewed to the right)

Negatively Skewed Distribution

Positively Skewed Distribution