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Histograms. Presented by William 2 !. (William Chen and Gulian ). What it is. A histogram looks like a bar graph but instead divides the data set into different ranges. Over each range is placed a block or rectangle whose height represents the number of data values in the range.
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Histograms Presented by William2! (William Chen and Gulian)
What it is • A histogram looks like a bar graph but instead divides the data set into different ranges. Over each range is placed a block or rectangle whose height represents the number of data values in the range. • A frequency histogram uses vertical columns to show frequencies (without using ranges) such as : • How many times a score occurs
When to use • To group numbers in a data set into ranges • Weight • Height • Age • Time • Show frequencies (without using ranges)
Data needed • One numerical data set • Ranges to group the data set in (unless creating a frequency histogram) • Title • Axes Labels
Real Life Example • How long is your bus ride to/from school? • Your answers (in min.):
How we did it Prerequisites (for both): • Collect data. • Decide ranges to group data in.* Computer: • Enter data in Microsoft Excel. • Select data and insert Column/Bar Graph. • Select the bars on the chart, right-click, then select “Format Data Series”. • Slide the “Gap Width” slider all the way to “No Gap”. • Customize so it is creative/original! Handwritten: • Draw x- and y- axes and label the x-axis as your ranges/numbers and your y-axis as frequencies. • Draw your bars like in a bar graph but with no gaps in between. (This is a difference between a bar graph and histogram.) • Decorate! *Skip step if you are creating a frequency histogram. (If you are making a frequency histogram, don’t use ranges.)
Checking for Understanding • What percentage of the class has bus rides longer than 20 minutes? • About 43%
Advantages vs. Disadvantages • Numbers are grouped into ranges so that trends can be observed • Can show frequencies • Actual data (numbers) not actually seen • Can only graph one data set
Thank you! http://www.mathsisfun.com/data/histograms.html http://www.google.com/imghp?hl=en&tab=wi The combined brainpower of William2!