### Lab 2 Graphing Qualitative Data (Bar Plot and Pie Charts)

```Math 134
Lab 2
Graphing Qualitative Data (Bar Plot and Pie Charts)
The purpose of this lab is to teach you how to perform exploratory data analysis by graphically plotting qualitative data
using bar graphs and pie charts, for qualitative (or categorical) variables. We will make graphs using data from “Cereal
Nutrition” found on our class group data site. Open the data file and read the description of the data set’s variables.
Background information: The “Cereal Nutrition” data contains nutritional information and grocery shelf location for several
different brands of cereals. Current research states that adults should consume no more than 30% of their calories in the
form of fat, they need about 50 grams (women) or 63 grams (men) of protein daily, and should provide for the remainder of
their caloric intake with complex carbohydrates. One gram of fat contains 9 calories and carbohydrates and proteins
contain 4 calories per gram. A "good" diet should also contain 20-35 grams of dietary fiber.
In this lab we’ll investigate the marketing behind shelf location of many cereals and analyze the cereal sugar content by
targeted consumer (adult vs. child) for cereals.
Lab Instructions:
Step 1. Make bar plots. Select Graphics/Bar Plot/with data. Select “Manu” as your column.
Click next and select Type: “Frequency” and Order by: “Count Ascending” and check “Display values above bars if possible”.
Click next and type in an appropriate label for the X axis and a great Title for your graph. Remember Who, What, Where,
Select “Create Graph!”
Export your results by clicking the “Options” in upper left hand corner of the graph window. Select “Export to my results”..
Print in color.
Step 2. Repeat Step 1 only choose Order by: “Count descending”. Repeat and choose “Value Ascending”. Repeat and
choose “Value Descending”. You can accomplish this quickly by using the “Options” in the upper left hand corner and
selecting “EDIT”. This will give you 4 bar charts of the same data.
Step 3. Make pie charts. Graphics/Pie Chart/with data. Select “Manu” as your column.
Click next. Select “Percent of Total” and deselect “Count” so that the percents are displayed and NOT the counts.
Click next and type in an appropriate Title. Include your name in the Title for your graph. Select “Create Graph!”
Export your results. Print in color.
Research Question: What is the relationship between whether the target consumers of the cereal are adults or children
and location of the cereal: on the bottom, middle or top shelf? For marketing reasons, we will note where the kids’ cereals
are located compared to healthy cereals. You wouldn't put Frosted Flakes on the top shelf out of kids' reach would you?
You will plot side-by-side split bar plots for shelf location grouped by consumer target by the following steps:
Step 4. Make side-by-side split bar plots. Select Graphics/Bar Plot/with data. Select “Shelf” as your column.
Locate the “Group by” pull-down menu. Select “Target” in the pull-down menu. Select “Split bars”.
Click next. For the Type select “Percent of Total” in the pull-down menu. Make sure the “Display values above bars if
possible” option is checked.
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Click next and type in appropriate labels for the X and Y axes. Give your graph a descriptive Title, as always, include your
name. Make sure “Use same Y axis” and “Draw horizontal grid line” options are checked. Select “Create Graph!” Tip: You
ought to produce a bar plot with two colors, one for Adults and one for Children. If you see more than two colors, make
sure that rows or columns in the data file are NOT selected.
Export your results. Print in color.
Step 5. Highlight the Middle Shelf bar that represents Children by left-clicking and dragging a box inside the bar. Note that
rows within the “Cereal Nutrition” data file are highlighted. The highlighted data items correspond to those that comprise
the bar you outlined in the bar plot. Make a note of these cereals as your discussion question will ask you about them. To
de-select the highlighted data rows, click on the word “Row” in the upper-left corner of the data file. Tip: This only works in
the active window with the “Options” button in the upper left corner. You can not do this task if you open the graph from
“My Results”.
Discussion questions:
1.
Is “Manufacturer” a qualitative nominal, qualitative ordinal, quantitative discrete or quantitative continuous
variable?
2.
Describe the distribution of the manufacturers.
3.
Is “Shelf” a qualitative nominal, qualitative ordinal, quantitative discrete or quantitative continuous variable?
4.
How many kids’ cereals are located on the middle shelf? List these cereals.
5.
Use your split bar plot to answer the stated research question. Research Question: What is the relationship
between whether the target consumers of the cereal are adults or children and location of the cereal: on the
bottom, middle or top shelf?
A complete lab 2 will have in this order:
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A cover sheet with your name, class meeting time, professor’s name and lab number in the upper right
hand corner. All labs for the entire semester must have a cover sheet just like this.
Computer output consisting four bar plots and one pie chart and one side-by-side split bar plot all printed
in color.
Typed discussion questions along with the answers. For this and all future labs use a word processor to
copy the entire discussion questions and give your answer in complete, grammatically correct sentences.
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