# CONFIDENCE INTERVALS FOR THE DIFFERENCE BETWEEN TWO PROPORTIONS

### Lesson 9

This is a Socratic lesson, starting with a teacher led discussion about developing inferences about the difference between the proportions of two populations. Students will find the familiar theme of sample parameters and margin of errors already seen in the previous lessons of this unit. The second part of the lesson has a real life example. The Classroom Investigation is the third part of the lesson and is a technology simulation that illustrates the computation of a confidence interval for the difference of two population proportions using Excel. Moreover, each group of students will compute their own confidence interval based on their own sample proportions, and hopefully, somebody’s confidence interval will not contain the true difference of the population proportions providing a deep understanding of the statement “with 90% confidence …”

### Teacher Materials

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