3.2 Frequency

Unit 3, Lesson 2: Frequency

• frequency - the number of data items in an interval  

• frequency table - a table that shows data values grouped into intervals and the frequency for each interval  

• histogram - a type of bar graph that displays data from a frequency table where the height of the bar shows the frequency of the interval it represents

• line plot - a line plot is a graph that shows the shape of a data set with X's above each data value on a number line

Line Plot

• You can also draw a line plot to show each of the values in the frequency table.

• Notice, there is an x placed above each value for the number of times the value Occurs.

• For example, there are three students whom are 5'4 so, there are three x's above the 5'4 on the line plot.

• Sometimes, this is referred to as a dot plot and instead of x's placed above each value, there will be dots.

Frequency Table

• You can organize data by the frequency of the values.

• When we organize data this way, it helps us easily assess how the data is grouped and you can quickly see if there are any gaps, outliers, and which values occur most frequently.

• To the right is a frequency table that shows the heights of 10 8th grade students.​

• Notice the tally marks add up to 10 (representing the 10 students).​

Frequency Table cont'd

​Here is a frequency table to represent a group of values rather than an individual value.

Histograms

• ​A histogram is a type of bar graph that displays data from a frequency table where the height of the bar shows the frequency of the interval it represents.

• You can use information from the frequency table from the previous slid (and below)e to create a histogram.

We'll take a look at some problems on your Quick Check.