What Shape Is My Graph How many bumps

What Shape Is My Graph?

How many bumps does it have? • Unimodal (1) • Bimodal (2) These “modes” should be very noticeable. We are not interested in every tiny little change. Look for the overall pattern. CAUTION: This descriptor alone (unimodal/bimodal) is usually not enough. It is an additional descriptor used with symmetric graphs. Occasionally bimodal can be used alone but not unimodal.

Shapes • Symmetric • Skewed Left For skewed graphs the direction corresponds to the location of the TAIL. • Skewed Right • Uniform

When describing the shape • It is okay to use “ly” words! The graph doesn’t have to match the shape perfectly. • Roughly symmetric • Approximately uniform • Your goal is to describe what you see as best as you can.

What Shape? Very few people die young Many people live a long life The x-axis shows age from 0100 ish years.

What Shape? This graph comes up a lot so know that it has this shape. Also, variables that are related to income will have this skewed right shape.

What Shape? • Consider a data set containing IQ scores for the general public. What shape would you expect a histogram of this data to have? • Symmetric Skewed to the right • Skewed to the left Bimodal • Symmetric • Consider a data set of the scores on a very easy exam in which most score very well but a few score very poorly. What shape would you expect a histogram of this data to have? • Symmetric Skewed to the right • Skewed to the left Bimodal

Your Turn! • On your paper, write down the name for the graph shown based on shape. • When describing a graph as Symmetric, you should include whether it is unimodal or bimodal.

Answers Symmetric, unimodal Uniform Skewed Right Skewed Left Skewed Right Approximately uniform Females – roughly symmetric; Males – skewed right • Skewed right • Fairly symmetric and unimodal • Bimodal • •