Relative Frequency Graphs When the proportion or percent matters more than the raw counts 11/28/2018

What’s old and what’s new? Frequency Relative Frequency The horizontal axis has the classes The vertical axis has the frequencies, the counts The horizontal axis has the classes The vertical axis has the relative frequencies How many in this class Divided by How many total Values from 0.00 to 1.00 Or 0% to 100% of the total 11/28/2018

Compute the Frequencies Remember, these graphs and charts all start with a table of data, a Frequency Distribution The Frequency Column alone isn’t enough. You need a Relative Frequency column How many items in each class Divided by How many total items Equals a number from 0.00 to 1.00 Equals a percent from 0% to 100% 11/28/2018

Relative Frequency Distribution for the Histogram Class Boundaries Frequency Relative 19.99995-24.99995 9 8.7% 24.99995-29.99995 26 25.2% 29.99995-34.99995 23 22.3% 34.99995-39.99995 14 13.6% 39.99995-44.99995 7 6.8% 44.99995-49.99995 11 10.7% 49.99995-54.99995 10 9.7% 54.99995-59.99995 0.0% 59.99995-64.99995 2 1.9% 64.99995-69.99995 1 1.0% 11/28/2018

Histograms Regular histogram with counts Relative Frequency histogram 11/28/2018

Vertical Axes close-up Regular histogram with counts Relative Frequency histogram “How many runners” “Percent of runners” (Note: the closeness of the count values and the percent numbers is coincidental, since there were 103 runnners, close to 100, so the counts and percents are almost the same numbers. Usually it won’t turn out this way.) 11/28/2018

Similarly for other graph types The same thing happens with Frequency Polygons and with Ogives The horizontal axis stays the same. The vertical axis changes from a raw count to a percent of total Decimal proportions can be used instead of percents (0.14 instead of 14%, for example.) 11/28/2018