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Lesson 9: What is Typical?

Lesson 9: What is Typical?

Objective

You will learn about the typical value when looking at a distribution by finding the “center” and determining any point clusters.

Vocabulary

typical, center, shape, spread

Essential Concepts

Lesson 9 Essential Concepts

The “center” of a distribution is a deliberately vague term, but it is one way to answer the subjective question "What is a typical value?" The center could be the perceived balancing point or the value that approximately cuts the area of the distribution in half.

Lesson

  1. Food Habits Campaign Survey Responses:

    1. You will be using the Campaigns Tool to view your survey responses. The IDS Campaigns Tool is found on your IDS Homepage: https://tools.idsucla.org. Click on Campaigns and sign in if prompted. Find the Food Habits campaign and click on Responses. If you haven't submitted any data, the page will be blank.

    2. Click on the blue plus sign (+) to expand the surveys you have submitted.

      1. Do the values for the variables seem reasonable?

      2. Did you include any pictures of your snacks? If so, is there anything in the picture that can be connected back to you or someone you know?

      3. What can you do to increase your data collection?

      Note: If there is a survey that you want to delete, click the check box on the left-hand side of the survey, go to Actions, and choose Delete Selected from the drop-down menu.

  2. Today you will be learning about a distribution’s typical value.

  3. If someone asked you about a typical student at your school, how would you describe them?

  4. What are some synonyms for the word “typical”?

  5. Below is a bubble map with synonyms that the Stick Figures brainstormed for "typical".

    Using these synonyms and the ones you brainstormed in #4 above, write in your IDS Journal which terms apply best to categorical variables and which terms apply best to numerical variables.

  6. Consider the dotplot of the distribution of calories from Lesson 8.

    1. What value might you consider to be the typical value of this distribution? Why?

    2. A good way to estimate where the typical value of a distribution lies is to look for the following:

      1. Clustering/clumps of data.

      2. Most of the observations are between _ and _.

      3. Overall range of the data.

  7. Now that you've been provided with some hints for how to estimate the typical value of a distribution, reconsider the typical number of calories in the dotplot that you reported in 6a. Do you still feel that what you reported is the typical number or calories in the Stick Figures' snacks? Why or why not?

  8. Another synonym for the term "typical" is center. Center, however, is useful for numerical variables. For example, the typical number of calories in the Stick Figures' snacks is centered around 100 calories.

  9. The value at the center of the distribution often matches up with our everyday notion of the typical value of a distribution. The middle observation is not always the typical value.

  10. Defining the center of a distribution depends on many things, such as the placement of points in the distribution (known as the shape), and how dense the distribution is at certain values (known as the spread).

  11. If you were to ask a group of high school students to write down the number of hours of sleep they got during a school night...

    1. What do you think the typical value will be?

    2. What do you think the lowest value will be?

    3. What do you think the highest value will be?

    4. What do you think the shape of the distribution will look like?

  12. Below is the distribution of number of hours slept on a school night by high school students.

    Is the typical value similar to what you originally thought? The shape? The variability? Why or why not?

  13. If you were to ask the same group of high school students to write down the number of hours they plan to sleep on a Saturday...

    How do you think this plot will differ from the first plot where they reported how many hours they slept on a school night? Make a quick sketch. Focus your explanation on the shape, center, and spread of the distributions.

Reflection

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

Homework

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