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Lesson 8: Tangible Plots

Lesson 8: Tangible Plots [The Data Cycle: Analyze Data]

Objective

You will learn how distributions help us organize and visualize data values, and that the shapes of the distributions give us information about the variability of the data.

Vocabulary

visualization, x-axis, y-axis, frequency, minimum, maximum, distribution, range, dotplot, data points

Essential Concepts

Lesson 8 Essential Concepts

Distributions organize data for us by telling us (a) which values of a variable were observed, and (b) how many times the values were observed (their frequency).

Lesson

  1. Food Habits Campaign Data Collection Monitoring:

    Your teacher will be monitoring your class's data collection using the Campaign Monitoring Tool. Watch the following video to see the Monitoring Tool capabilities. Have you been submitting your surveys? Keep in mind that this tool will inform your teacher about whether or not you are collecting data.

  2. In this lesson you will be learning about data visualization.

  3. Watch the Value of Data Visualization video at https://www.youtube.com/watch?v=xekEXM0Vonc, which describes the importance of graphical representations of data. As you watch the video, respond to the following questions in your IDS Journal:

    1. What is data visualization?

    2. What is one example of how visualization can be used to increase data comprehension?

  4. The video’s last statement was: “Your message is only as good as your ability to share it.”

    1. What does this statement mean?

    2. What makes a good message in terms of data and visualizations?

  5. Find your nutrition facts labels or pictures and your Food Habits Data Collection handout from Lesson 6.

  6. The Stick Figures from Lesson 2 s have decided to create visuals using the nutrition labels. They have selected two numerical variables and one categorical variable from the Food Habits Data Collection handout because they would like to see a visualization, or a picture of the data.

  7. The Stick Figures begin by creating a visualization of the categorical variable salty_sweet.

  8. Since the variable has two categories, they label the x-axis with the categories Salty and Sweet. The y-axis has the label frequency, which simply means the number of labels that are either salty or sweet. Tick-marks are not needed on the y-axis because the frequency will be measured by counting the number of labels on the visualization.

  9. The Stick Figures start by drawing an x-axis and a y-axis to show the first quadrant of a coordinate plane.

  10. Next they place the nutrition labels where they belong along the x-axis.

  11. The Stick Figures place their nutrition fact labels above the category that describes their snack. Notice how they stack their nutrition labels to make it easy to calculate the frequency. Choose one of your nutrition labels and decide whether it's salty or sweet.

    Where would you place your nutrition label?

    How many salty snacks were recorded? How many sweet snacks were recorded?

    Since the labels are different sizes, you'll need to create a bargraph to get a better representation of the frequency in each category.

  12. Respond to the following questions in your IDS Journal:

    1. How many data points does this distribution have? Why?

    2. What information is this visualization telling us about the type of snacks the Stick Figures consume?

  13. The Stick Figures are interested in analyzing the amount of grams of sugar in the snacks they consume so they create a second visualization, this time for one of the numerical variables. Again, they start by drawing an x and y axis. They decide that an x-axis labeled with numbers is appropriate for a numerical variable.

  14. Before the x-axis can be labeled, the minimum (the lowest number of grams of sugar of all of the nutrition labels) and maximum (the highest number) values for the grams of sugar need to be determined. The y-axis will be labeled frequency, which simply means the number of times a value occurs. There is no need to place tick-marks on the y-axis. The frequency will be measured by the number of labels plotted.

  15. The Stick Figures study the coordinate plane and look for the number on the x-axis that matches the number of grams of sugar on each of their nutrition labels. They then place each nutrition label above its matching value on the x-axis. Choose one of your nutrition labels and find the grams of sugar it has.

    Where would you place your nutrition label?

  16. Observe the distribution of grams of sugar and respond to the following questions in your IDS Journal:

    1. What are the minimum and the maximum values of the data set?

    2. The range is the largest value minus the smallest value. It is one way of measuring the variability of a variable.

      What is the range, and why do you think this measures the variability?

    3. How many data points does this distribution have? Why?

    4. What is the amount of grams of sugar that appears most often in a snack? Why?

    5. What do you think the phrase "distribution of the data set" means?

    6. What information is this distribution telling us about the grams of sugar in the snacks that the Stick Figures consume?

    7. A distribution tells us two things: the values of the variable and the frequency of the values. "Frequency" is just another way of saying "the count."

      Why is this plot a picture of the distribution of grams of sugar?

  17. You will be provided with an opportunity for feedback on your responses.

  18. Below is the distribution of number of calories in the Stick Figures' snacks.

    1. How many data points does this distribution have? Why?

    2. What is the number of calories that appears most often in a snack? Why?

    3. What information is this distribution telling us about the number of calories in the snacks that the Stick Figures consume?

  19. You will now learn how to convert the nutrition facts labels into something that is easier to read. We can represent each label with an item such as a dot, dot sticker, or a sticky note.

  20. Notice that the x-axis is the same as before. You simply replaced each nutrition label with a dot that corresponds with the number of calories in the snack. If two snacks had the same amount of calories, you simply stacked the dots. This type of plot is called a dotplot since dots are used to represent each observation.

    How/why is the dotplot a better representation of the data?

  21. The Tangible Plot handout contains the nutritional information for the total grams of fat in the Stick Figures' snacks.

    Click on the document name to download a fillable copy of the Tangible Plot handout (LMR_1.9).

  22. Think about the visuals in this lesson.

    What kind of graph was used to visualize the categorical variable? What kind of graph was used to visualize the numerical variable?

    Think about the statistical questions you came up with for your Lesson 6 homework.

    Which visualization would be most appropriate for answering your statistical questions?

Reflection

What are the essential learnings you are taking away from this lesson?

Homework

Complete the Tangible Plot handout (LMR_1.9) and turn it in for assessment.

Continue to collect nutritional facts data using the Food Habits Participatory Sensing campaign on your smart device or via web browser.