The LessonA frequency table shows how often (how frequently) each number appears in a list of numbers. Imagine you had a set of numbers:
A frequency table is a way to present this data in a simpler way:
Understanding the Frequency TableThe frequency table tells you each number that appears in a list of numbers and how many times each number appears. Let's look again at our list of numbers (rearranged in order and each number counted):
We see that 5 appears 2 times.
We write 5 in the Number column. It is the lowest number that appears in the list of numbers.
We write 2 in the Frequency column because 5 appears 2 times in the list of numbers.
We see that 6 appears 3 times.
We write 6 in the Number column. It is the next number (in numeric order) that appears in the list of numbers.
We write 3 in the Frequency column because 6 appears 3 times in the list of numbers.
Finding Averages from a Frequency TableThe frequency table can be used to find the average of a set of numbers. A frequency table can be used to find the mean, the median and the mode.
Other Types of Frequency TableThe frequency tables shown on this page are the basic type of frequency table. There are further variations on the basic frequency table.
A cumulative frequency table has another column which keeps a running total of the frequencies.
A grouped frequency table groups numbers together. It shows you how often numbers within each group appear in a list of numbers.
A cumulative grouped frequency table is a grouped frequency table that has another column which keeps a running total of the frequencies.
Frequency Tables Are for Discrete DataA frequency table is for discrete data. Discrete data can only take certain values. For example: 1, 2, 3. It can't take values in between these values: it can't take 1.5. This is unlike continuous data, which can take any value (within a range). For example, it may take any value from 1 - 10: 1.5, 2.31, 3.05.
What's in a Name?"Frequency" means how often something occurs.
Other Column HeadingsIn the frequency table, the column headings are Number and Frequency. This needn't be the case. Imagine the numbers in the list represented test scores. A more descriptive heading for the Number column might be Score. The numbers could represent many other things: incomes, heights, number of pets. Use a descriptive heading in the frequency table (Income, Height, No. of pets).
Frequency Tables with Non-Numeric ItemsThe items in a set needn't be numbers. Imagine there was a list of the pets that students have:
Dog, Cat, Rabbit, Dog, Dog, Cat, FishThis could be presented in a frequency table: