Graph

Measures of Center and Variability

By Maria Isok

Dot Plot

A dot plot is a graph that uses dots to represent single observations from a data set. The dots of a dot plot are organized in categorical columns, and the height of each column represents the frequency of observations for each category.

Example: A group of 20 scout students won several badges. The table shows the number of badges won by each student.

​A dot plot is useful for showing relatively small sets of data, since all the data values are shown.

Multiple Select

Which of the following is TRUE?

• There are 3 students who won 4 badges .

• 8 students did not receive a badge

• The Median and the Mode is the same.

• The shape of the graph is skewed to the right.

A histogram is a graph composed of bins, or equal-width columns. Each column represents a quantitative variable, and the height of each column represents the size of the quantitative variable.e this with a header

A histogram is useful for showing the frequency distribution of data within equal intervals or ranges. The width of each bar represents different ranges and the corresponding height represents the value for the range.

Multiple Choice

In which interval is the median?

• 2 - 3

• 4 - 5

• 6 - 7

• 8 - 9

A box plot is a method of displaying and interpreting a set of data. The data is first arranged in numerical order (from lowest to highest) and then sorted into two equal parts at the median, or "middle point."

​A box plot is useful for showing the distribution of data based on the minimum, first quartile, median, third quartile, and the maximum of the data set. It displays the range along a number line.

Multiple Choice

Which of the above representations is the most appropriate if all the data points need to be shown?

Match

Using the box and whisker plot. Match the following data.

• lower quartile

• minimum badge won by students

• 3rd Quartile

• highest number of badge

• Median

3

2

6

9

5

• 3

• 2

• 6

• 9

• 5

Match

Match the following.

• How many badges were receive by 4 students?

• How many students won a badge?

• Median and Mode

• stray data

• Range

3

20

5

9

7

• 3

• 20

• 5

• 9

• 7

Match

Match the following data.

Skewed left

Symmetrical

Skewed Right

Bimodal

uniform

• Skewed left

• Symmetrical

• Skewed Right

• Bimodal

• uniform