Let’s look at our table of shoes after a few weeks in business.

When we had the same number of all the sizes – WE DID NOT PAY ATTENTION TO THE FACT that there aren’t equal numbers of feet at each shoe size.

Frequency distributions are graphs with the score on the X-axis and the frequency on the Y – axis.

For our shoe store example and not to go broke, we would take a randomly selected sample of men of sufficient size (usually > 120) and measure their feet.

Frequency distributions have different characteristics depending whether the data are nominal vs. ordinal or measurement.

Nominal frequency distributions are constructed as histograms (bar graphs). Like the following graph on the number of men and women at your school.

Measurement frequency distributions are constructed as continuous curves. Like the following graph on shoe size from our sample.

Hints:

This is the normal curve and the line in the middle is the mean.

Many frequency distributions in Psychology are normal (sometimes called bell shaped)

A little box on the graph represent a score.

Distributions can come in various other shapes:

1: Skewed with the more scores to the left or right.

Positive Skew		Negative Skew

2. Bimodal (also multimodal) with more than one peak.