Authentic Learning Task (ALT) #7: Hard Candy

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Overview

In this Authentic Learning Task (ALT), you run a test comparing two populations simultaneously. You analyze two different flavors of candy to see if there is a difference in the weight. You then obtain and weigh a sample of each flavor, and then compare the average weights to see if there is a significant difference. As in ALT #5, you run a t-test, but with a standard error value that measures the variation of the differences between two sample means taken from two populations. Instead of a table of t-values, you use Excel to run this test.

After completing this ALT, you should be able to demonstrate the following competencies:

• Use the techniques of sampling andrecognize the nature of variability in sample data, including the use of computer analysis tools (Comp. 2).
• Analyze variability in a process using hypothesis testing
  (Comp. 5).

Materials and Equipment
No materials or equipment are needed for this ALT.

Safety and Disposal
No special safety or disposal procedures are required.

Pre-Activity

In this activity, you address the question: Are there differences in weight between to candy colors? This problem question is of the general form: “Is there a significant difference between (among) the sample means?"

Click here to access the Decision Tree to aid in the selection of the proper test. In this case, you will sample from two colors of hard candy and then weigh the individual pieces to determine if there is a significant difference.

Hypothesis testing - t-test
The t-Test is typically used to compare the means of two populations. If you are not sure whether or not the sample variances are the “same” then choose the Assuming Unequal Variances option. The sample variances will be tested using the F statistic to determine whether or not they can be pooled - they have the same variability and thus can be combined to determine a pooled standard deviation.

Visit the Guide to Basic Laboratory Statistics (t-test background and java applet). Click student t-test applet in left column to use the web based calculator on the data or acess a calculator here.
Compare your answers to the worked example in the Participant Journal.

Example solution from StatCrunch:

Self Assessment

Click here to access the self assessment problem. Answers to the self assessment can be found here.

Activity

In your team, perform the following steps to complete the activity:

1. Refer to Information Sheet: Comparing Two Populations with a T-Test.
2. Record the weight of each piece of candy given to you by your mediator.
3. Complete Instruction Sheet: Testing Two Populations with Excel.
4. Complete Data Sheet: The Difference.

Post-Activity

Your team should now post all of its results from the activity to the Discussion Board.

Assignment
There are no instructions to prepare for Transfer Activity: Risky Drinking.

Assessment
Your facilitator may use Assessment Sheet: Hard Candy to evaluate your results from the activity and your posting to the Discussion Board.

Go to next Transfer Activity

Probability, Sampling, and Hypothesis Testing Home Page