Lesson 1.6 Frequency Table
Frequency
Frequency is the number of times that a particular result occurs. Let's consider an example involving a pre-school class.
Example:
A pre-school class has 14 children in it. There are 5 three year-olds, 7 four year-olds, and 2 five year-olds in that class. The frequency of three year-olds is 5. The frequency of four year-olds is 7. This data can be shown:
frequency of three year-olds = |
5
|
frequency of four year-olds = |
7
|
frequency of five year-olds = |
2
|
Think about it: What was the frequency of sunrises for the year 2000?
Frequency Table
Frequency tables are used to organize data. A basic frequency table consists of a column of data followed by a column of frequencies.
Example:
Look at the table below. It shows the three different ages represented in a pre-school class. The table columns show the ages (3-5) and how many students there are of those three ages in that class. Notice that the data is sorted in order from smallest to largest.
| Data: Age of children, in years, in a pre-school class |
Frequency: The number of children that particular age. |
|
3
|
5
|
|
4
|
7
|
|
5
|
2
|
Relative Frequency
Relative frequency (abbreviated RF) is the fraction or percentage of times an answer occurs. RFs can be written as decimals, fractions, or percents.
Example 1:
Calculate the RF of the age "four years-old" from the above pre-school example.
Total number of four year-olds: |
7
|
Total number of students: |
14
|
RF (of four year-olds): |
7/14 =
= 0.50
|
= 50%
|
Example 2:
Calculate the RF for "Saturday" for the month of June, 2000. June, 2000 had 30 days and four Saturdays. Therefore, the relative frequency of Saturdays was 4/30 (expressed as a fraction), 0.1333 (expressed as a decimal), or 13.3% (expressed as a percentage.
Think about it: Calculate the relative frequency of Mondays for this month.
Cumulative Relative Frequency
Cumulative Relative Frequency (abbreviated Cum. RF) is the accumulation of the decimal, fraction, or percent that occurs at that answer or lower.
Example 1:
Calculate the Cum. RF of age "four" in the above pre-school example. Cum. RF = RF of Target Group (four year-olds) + RF of Lower Value Answers (in this case, three year-olds only)
Cum. RF = |
RF (four year-olds) + RF (younger students) = |
7/14 + 5/14 = 12/14 |
Cum. RF for four year-olds is 12/14, or 0.857, or 86%.
Example 2:
A statistics class was surveyed the first day of class and the students were asked how many siblings (brothers and sisters) they had. Click on the play button below to see how the data were organized. Then look at the following table showing the Cum. RF calculated from that data.
Click on the red triangle to play the animation below. As each scene ends, click again to advance to the next scene. Read a text transcript of the animation.
This is the end of Lesson 1.
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