Lesson 1.3 – Displaying Quantitative Data: Dotplots

  • Make and interpret dotplots of quantitative data.
  • Describe the shape of a distribution.
  • Compare distributions of quantitative data with dotplots.

 

Activity: How many hours do you work?

We give students 2 minutes to discuss their current job within their small groups.  We hope to promote engagement by looking at data sets with relevant contexts for the students.  Here are the results:

Photo Sep 14, 10 53 57 AM

It was nice that our data set included a possible outlier as we can start to discuss the idea with the group.  Students were using laptops for this activity instead of Ipads because we needed Microsoft Excel for the Census at School data.  Students easily used the SPA applet to create a dotplot.

Be sure to ask students “What does each dot represent”.  The answer is one individual from the population.  This will be a very important question later in the course when we get into sampling distributions.  In a sampling distribution, each dot represents a different sample from the population and a statistic calculated from that sample.

**Be sure to take a picture of your data because you will need this data set for the Lesson 1.6 Activity.**

 

Census at School

In the Activity, students used www.amstat.org/censusatschool to collect data for a random sample of 50 Michigan 12th graders.  Then we compared our class data to the random sample.  Students at EKHS tend to work more hours than other 12th graders in Michigan (with more variability).

Census at School

 

Notes

When students are asked to “Describe a distribution”, it is expected that they address shape, center, variability, and outliers.  At this point, they don’t have specific ways to measure center and variability (this is Lesson 1.6 and 1.7), but it is important to get them thinking about them.  Have them take a guess at the center of the distribution and think about the lowest and highest value for variability.

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