General Statistics Section 2-2: Histograms, Frequency Polygons, and Ogives

What is the third step to constructing either one of the three graphs?

plot the frequencies for each class, and draw the vertical bars for the histogram and the lines for the ogive and frequency polygons.

What is the second step to constructing either one of the three graphs?

2. on the x-axis, label the class boundaries of the frequency distribution for the histogram and ogive. label the midpoints for the frequency polygon.

What is the first step to constructing either one of the three graphs?

1. Draw and label the x and y axes.

What happens when unimodal occurs?

distributions with one peak. (the highest peak of a distribution indicates where the mode of the data values is. )

How do you convert frequency into a proportion or relative frequency?

divide the frequency for each class by the totla of the frequencies.

Describe the attributes of a J-shaped distribution?

has a few data values on the left side and increases as one moves to the right.

Describe the attributes of a bell-shaped distribution?

has a single peak and tapers off at either end. It is approximately symmetric.

What is a histogram?

is a graph that displays the data by using contigous vertical bars (unless the frequency of the graph is 0.) of various heights to represent the frequencies of the classes.

What is a frequency polygon?

is 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.)

What is an Ogive?

is a graph used to represent the cumulative frequencies for the classes in a frequency distribution.

Describe the attributes of a uniform distribution?

is basically flat or rectangular.

Define mode.

is the data value that occurs more often than any other data value.

What is the purpose of graphs in statistics?

to convey the data to viewers in pictoral form.

What happens when bimodal occurs?

when a distribution has two peaks of the same height.

Describe the attributes of a negatively or left-skewed distribution?

when the data values are clustered to the right and taper off to the left.

Describe the attributes of a Positively or right-skewed distribution?

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

when do you use relative frequencies instead of frequencies?

when the proportion of data values fall into a given class is more important than the actual number of data values in the class.