Frequency and Histograms
Standard
S.ID.1 Represent data with plots on the real number line.
Goals for this section:
To be able to create and understand frequency tables and histograms (bar graphs).
Frequency Tables
Frequency tables are just counting the number of times a certain value occurs!
Given: The waiting times for a restaurant in minutes
5, 10, 15, 10, 5, 10, 15, 30, 45, 10, 5, 30, 30, 15, 45, 10, 5, 5
Tips: Notice that the waiting times are multiples of 5's. We can set up our interval in 5's.
Table with tally marks
The tally marks can be omitted in favor of just writing the number.
The total number should match the total amount of data that you have.
Dot Plot
This is another popular way to track frequency. You can also visually see how your data is concentrated heavily on the left side with the shorter waiting times. What could this data mean then?
Histograms
Histograms are what we commonly know as bar graphs!
Notice how the dot plot is very similar to a histogram.
Uniform
The bars are roughly the same height.
Symmetric
The histogram can be split in half and look almost like mirror images.
Skewed
The histogram has one peak that is not the center and does not split in half to look like a mirror image.