Categorical Variables in Scatterplots

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# Categorical Variables in Scatterplots - PowerPoint PPT Presentation

Categorical Variables in Scatterplots. Section 3.1.2. Starter 3.1.2. Write one example of a random variable that you think would have a normal distribution (other than rolling two dice). Write why you think it would be approximately normal.

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### Categorical Variables in Scatterplots

Section 3.1.2

Starter 3.1.2
• Write one example of a random variable that you think would have a normal distribution (other than rolling two dice). Write why you think it would be approximately normal.
• Write one example of a different random variable that you think would have a uniform distribution (other than rolling one die). Write why you think it would be approximately uniform.
Today’s Objectives
• Students will construct and interpret a scatterplot with 3 variables, one of which is categorical
• Yesterday you looked at 16 months of data showing gas usage as a function of degree-days (coldness).
• You stored the data in lists GASDA and GASFT
• Now suppose that the Sanchez family decided to add solar heating to their house and collected more data.
• I have stored the new data in two lists called GASD2 (degree-days) and GASF2 (100 cu. ft. used)
• Link calculators and get these data from me.
• I’m also giving you: MASSF, MASSM, METF, METM for use in the next activity
Display the new scatterplot
• Set Plot 1 in your calculator to show a scatterplot of GASDA and GASFT.
• Set Plot 2 to show a scatterplot of GASD2 and GASF2.
• Tap Zoom 9 to see the display.
• Can you tell which points represent the new data AFTER solar panels were put in?
• Probably not, so change the mark in Plot 2 to a plus instead of a box
• Write a brief verbal description of the difference between the two plots.
• What do you conclude in the context of this problem?
Both graphs have strong positive linear relationships, but the “plus” graph has a lower slope which means that as the months get colder, the gas usage goes up more slowly with solar panels than without.
Classwork ActivityProblem 3.9, page 120
• Does body mass affect metabolic rate? Is there a difference by gender? The data are in the lists I gave you:
• MASSM is the body mass of 7 men
• METM is the metabolic rate of those men
• MASSF and METF are the data for 12 women
• Make a scatterplot on the TI of the men’s data
• Add a scatterplot of the women’s data
• Write a paragraph that describes each association and any differences between them
Today’s Objectives
• Students will construct and interpret a scatterplot with 3 variables, one of which is categorical
Homework
• Read pages 117 – 122
• Do problems 10 – 13, 17