Describing Distributions

Describing Distributions Center Shape Spread

Shape • Always describe the basic shape of the distribution. • Symmetric – left and right side are mirror images, or approximate since we’re dealing with real data

Skewed Left – majority of the data is on the right side but tails out to the left • Skewed Right – majority of the data is on the left side but tails out to the right

Unimodal – one major mode where the data is collected around • Bimodal – two major modes • Multimodal – multiple modes • Uniform – data is flat and featureless

Also mention any unusual features • Outliers – observations away from the main distribution. Can be some of the most informative and interesting • Gaps – spaces between clumps of data

Center • Mean or Median • Right now, just approximate Spread • List the range of the data (min, max).

Example The distribution is unimodal and skewed to the right. The center is around 10 to 15. Most of the data is spread around 5 to 40. There is a possible outlier in the 55 to 60 bin. The distribution is unimodal and approximately symmetric. The center is around 5 to 6. Most of the data is spread around 3 to 9. There is a possible outlier in the 16 to 17 bin.

Practice – Describe the Distribution

Describing Distributions