2-2 Histograms, Frequency Polygons, and Ogives

J-shaped distribution

A few data values on the left that increases as one moves to the right

uniform distribution

Basically flat or rectangular

bell-shaped distribution

Has a single peak, tapers odd at either end; and is approximately symmetric

positively or right-skewed distribution

When the peak of a distribution is to the left and the data values taper off to the right

Histogram

a graph that displays the data by using contiguous vertical bars of various heights to represent the frequencies of the classes

Frequency Polygon

a graph that displays the data by using lines that connect points plotted for the frequencies at the midpoints of the classes. The frequencies are represented by the heights of the points.

Ogive

a graph that represents the cumulative frequencies for the classes in a frequency distribution

relative frequency graphs

a graph using proportions instead of raw data as frequencies

skewed distribution

data clustered at one end or another

Outliers

data values in the extreme ends

unimodal distribution

one peak

U-shaped distribution

the peaks are to the left and right

cumulative frequency

the sum of the frequencies accumulated up to the upper boundary of a class in a frequency distribution

bimodal distribution

two peaks of the same height

Negatively or left-skewed distribution

when the peak of a distribution is to the right and the data values taper off to the left