1. Input: Frequency Distribution Output: Pretty Picture
Histograms
Input: Frequency Distribution
Output: Pretty Picture
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2. Inputs and Outputs Output – a Histogram Numerical data
Input – Frequency Distribution
Output – a Histogram
Numerical data
Not categorical data
Grouped into classes
Each class has a count, a frequency, how many data values fall within that low-to-high class.
Horizontal axis has numerical class boundaries
Vertical axis has frequency of classes.
Height of each bar indicates the frequency of the each class
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3. Copyright information
A couple of the slides which follow are taken from the Bluman 5th Edition PowerPoint, ©McGraw-Hill.
The Bluman data is shown on slides with a rose background.
Some of the data is reused on subsequent slides with original, non-publisher commentary.
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4. Input: a frequency distribution
The data set: Someone listed the fifty states of the USA and the all-time highest temperature recorded in each state.
The data were grouped into a frequency distribution. Each class is a low-to-high range of temperatures.
We have the right ingredients for a histogram:
Frequency distribution (classes and counts)
Numerical data (not categorical)
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5. The Frequency Distribution
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Bluman 5th Ed. (c) Mc-Graw Hill

6. Histograms
Histograms use class boundaries and frequencies of the classes.
Bluman, Chapter 2 (c) McGraw Hill

7. Important Design Notes!
The horizontal axis is labeled with the class boundaries (not the class limits).
There are no gaps between bars.
The class boundary labels happen on the boundaries between the bars.
There is a label telling us what the values are measuring – here, it’s “Temperature ( ⁰F)”
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8. Important Design Notes!
The vertical axis begins at 0.
Tickmarks are well-chosen.
The vertical axis is labeled. It probably would be better to label it “How many states” rather than just “Frequency”.
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9. TI-84 and Histogram STAT PLOTS has a histogram feature
But the screen size is so limited
TI-84 histograms might be useful for informal exploratory work
TI-84 histograms might be useful for small supplementary illustrations
But professional and business situations need something better
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10. Excel and Histograms
Being able to produce professional-looking charts in Excel is a very important today’s world !!!!!
It is well worth your time to develop your skills (and learn from your mistakes) NOW in this course, rather than waiting until you’re facing a deadline on a research paper or a workplace project.
See separate handouts for helpful info.
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11. Excel and Histograms
You can choose the “Column” chart and do it directly.
Or you can have the Data Analysis add-in generate the chart.
Either way, 90% of the job is quick & easy.
But it will take some thinking and some labor to turn the first graph into something professional.
Labels, titles, scaling, styling – these all take time
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12. Excel and Histograms Excel blurs the distinction between
Histograms for numerical classes
Bar charts for categorical distributions
But this course makes a big deal about it
Some people “out there” make a big deal about it, too.
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