Making Random Samples and Asking Statistical Questions

Focus Questions:

How do I make a random sample?
How do I ask a "statistical question"?
How big should my random sample be?

Part 1: Making Random Samples

In this part of the lesson, we are going to look at some different strategies for making random samples.

Consider this question:

Mr. Ray wants to give chocolate to three randomly selected students.  How could he do this in an "unbiased way"?

Our student data form has almost 300 entries, so some of the strategies that were suggested, might not work as efficiently.  So, we will use a random number generator to do the hard work for us.  In order to do this, you will need your own copy of the "Samples and Populations - Student Information Responses"

• Click on the following link: Samples and Populations - Study Copy
• Make a copy of the form and rename it so that is says "Samples and Populations - YOUR NAME Copy"
• File it in an appropriate place in your GoogleDrive.

We are now going to generate 6 different random samples as indicated on the spreadsheet.

Part 2:  Asking Statistical Questions

In this part of the lesson we are going to start asking statistical questions that we can use our data to help us answer.  When asking these questions, we need to keep in mind a couple of things:

• What is the population in which you are interested.
• Do you want to find out about one population or would you like to compare populations.

Here are some examples:

• Are 7th grade boys are statistically taller than 7th grade girls?
• Do girls on B-side have statistically more Facebook friends than girls on C-side?

Part 3: Comparing Sample Sizes

One question that has come up a lot in our class is how big should a sample be?  That is a great question.  Here is what we are going to do:

• As a class, we will choose one quantitative "parameter" to focus on.  Examples could be height, shoe size, number of siblings, age etc.
• Find the mean for each of your random samples of your given gender.
• Place a sticker on the number line to represent the mean for your sample size.

Here is what you MUST do before next class:

• Complete your random samples of both boys and girls.
• ACE (15, 16, 17, 19)
• We will do the survey as a "Do Now" next class.