Learning Goals
In this support activity you’ll become familiar with the following:
- Use technology to create a dotplot from a dataset.
- Answer questions about a variable using a dotplot.
- Use a random number generator to select a random sample.
- Anticipate sample-to-sample variability.
You will also have an opportunity to refresh the following skills:
- Calculate a sample mean by hand
In the next preview assignment and in the next class, you will need to interpret features of a dotplot, use a random number generator to select a random sample from a finite population, and calculate the arithmetic mean. In this activity, you will become familiar with the data analysis tools that will be used throughout this course. You can access these tools on any smart device, including a phone.
Some new vocabulary will appear in this section of course material. These are terms you’ll discuss in greater terms later, that you’ll use throughout the course, and that you may have seen before. As you work through this assignment, try to draw the statistical meaning of the words random and sample as they are used in context.
The two tools in this activity are the Describing and Exploring Quantitative Data tool at https://dcmathpathways.shinyapps.io/EDA_quantitative/ and the Generate Random Numbers tool at
https://dcmathpathways.shinyapps.io/RandomNumbers/. They’ll also be linked below as you need them.
Work in pairs during this activity if possible, in close proximity so that you can share and compare the outputs from the tool. If more than one of you share a device to complete the activity, switch roles halfway through so everyone gets practice using the tools.
Interpreting Dotplots
[insert image of a generic dotplot with labels, arrows pointing to individual observations, horizontal axis]
A dotplot is a graphical display of the distribution of a quantitative variable. It shows the variable’s possible values and the frequency of each value. In this corequisite support activity, you will use technology to generate a dotplot and then use the dotplot to describe the features of the distribution. You will explore other ways of visualizing a quantitative variable in Forming Connections [3C].
question 1
Go to the Describing and Exploring Quantitative Data tool at https://dcmathpathways.shinyapps.io/EDA_quantitative/.
Step 1) Select the Single Group tab.
Step 2) Locate the drop-down menu under Enter Data and select From Textbook.
Step 3) Locate the drop-down menu under Dataset and select Cereal Sodium Content.
Step 4) Under Choose Type of Plot, uncheck Histogram and Boxplot and check Dotplot. Then adjust the Dot size to 0.5 and the Bin width to 10.
Use the dotplot displayed in the tool to answer the following questions.
Part A: Which type of variable is cereal sodium content?
Part B: Describe the typical value of cereal sodium content.
Part C: How many observations of cereal sodium content are less than 100 milligrams (mg)? Approximately what are the values of these observations?
Part D: How many observations of cereal sodium content are between 200 and 300 mg (including 200 and 300)?
You’ll be using the tools frequently throughout this course, and detailed instructions will be provided for each of the first few times you do, so don’t worry if it doesn’t yet feel comfortable.
Let’s turn our focus now to another tool you’ll need to use soon, the random number generator.
