Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum

Session 2, Part E:
Bar Graphs and Relative Frequencies

In This Part: Frequency Bar Graphs | Relative Frequency | Comparing Representations

 The line plot is a useful graph for examining small sets of data. It's especially helpful as a device for learning basic statistical ideas. However, for larger data sets, it can be awkward to create, since for each data value there is a corresponding dot. That's a lot of dots for data sets with hundreds or thousands of values! You can, however, replace a line plot with a frequency bar graph. Let's look at the transition from line plot to frequency bar graph. We start with the line plot we've been using. Remember that the number of dots over each value on the horizontal axis corresponds to the frequency of that data value: Now draw a rectangle over each value, with a height corresponding to the frequency of that value: Now remove the dots, and add a vertical scale that indicates the frequency of each value on the horizontal scale: The frequency bar graph contains the same information as the line plot for the counts of raisin boxes, but it doesn't indicate the raisin count for each individual box. The height of each bar or rectangle tells us the frequency for the corresponding raisin count.

 Session 2: Index | Notes | Solutions | Video