Hypothesis Testing with Two Groups

Problem Set 7.1: t Test with Related Samples

• Criterion: Differentiate between independent samples, repeated measures, and matched samples.
• Data:
  • Scenario A: A researcher wants to know whether men or women spend more money at the movie concession stand. He asks the concession clerk to identify customers as male or female by marking their gender on each saved receipt.
  • Scenario B: A CPR instructor wants to know if her students are learning anything during her 90-minute training. She decides to quiz her students at the beginning of class and again at the end of class.
• Instruction: For each of the two scenarios, identify whether independent samples, repeated measures, or matched samples would be used. Explain how you can make the determination.

Problem Set 7.2: Paired Samples t Test in SPSS

• Criterion: Calculate a paired samples t test in SPSS.
• Data: Dr Statistics wanted to test how her learners scored on a problem set when she presented the problems sequentially versus when she presented the problems randomly. She had 10 learners who scored the following:

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• Instruction: Complete the following steps:

• Open SPSS and open a New DataSet.
• Click on the Variable View tab.
• Enter Sequential in row 1 and enter Random in row 2.
• Click on the Data View tab. Enter the data for each learner.
• In the Toolbar, click Analyze, select Compare Means, and then select Paired-Samples t Test.
• Select Sequential and then click Arrow to send it over to the Variable 1 box.
• Select Random and then click Arrow to send it over to the Variable 2 box.
• Click OK and copy and paste the output into the Word document below.

Problem Set 7.3: Paired Samples t Test in SPSS

• Criterion: Analyze a paired samples t test to make the decision about the null hypothesis.
• Data: Use the data from Problem Set 7.2.

• Instruction: Complete the following:
  • Compare t with the one-tailed critical t at the .01 α level.
  • Answer this: Did the learners who received sequenced problem sets score significantly higher?Why or why not?
  • State your decision about the null hypothesis.

Problem Set 7.4: Confidence Intervals

• Criterion: Calculate a confidence interval in SPSS based on the results of a related samples t test.
• Data: Use the data from Problem Set 7.2.
• Instruction: Answer this: Based on that output, what is the 95 percent confidence interval of the difference?