Thursday HW:

Tonight, please complete the Inference for 2 Proportions worksheet provided in class. If you lost it, the questions are below.

Tomorrow we'll use the class period to work in groups and do some more 2-proportion z-test practice, and then we might look at a Stat Rap assignment.

Friday is test day! Vocab, a 2 proportion z-interval, and a 2-proportion z-test! If you can do tonight's homework, you know all of the math you need to know for chapter 22!

Inference for Two Proportions

1.)    Among 242 Cleveland-area children born prematurely at low birth weights between 1977 and 1979, only 74% graduated from high school. Among a comparison group of 233 children of normal birth weight, 83% were high school graduates.

a.) Verify that the conditions for a 2 Proportion Z Interval are met.

b.) Create a 95% confidence interval for the difference in graduation rates between children of normal and very low birth weights.

c.) Interpret the meaning of your interval, in context.

d.) Based on your interval above, do you believe there is a significant difference in the proportion of normal and low birth weight babies who graduate? Explain your reasoning.

2.) Using an appropriate hypothesis test, determine if there is a statistically significant difference between graduation rates of normal and low birth weight babies. (We’ll skip the conditions since they’ve been checked above).

                i.) State your null and alternative hypotheses, using appropriate notation.

ii.)  Find the z-score and then your p-value. Show a sketch of a Normal model with the p-value shaded and labeled.

iii.) Interpret your p-value, in context.

3. Among 242 Cleveland-area children born prematurely at low birth weights between 1977 and 1979, only 74% graduated from high school. Among a comparison group of 233 children of normal birth weight, 83% were high school graduates.

a.) Based on this scenario regarding premature children explain what Type I error would be and name one consequence.

b.) Based on this scenario regarding premature children explain what Type 2 error would be and name one consequence.

c.) Based on your answers above, would you prefer a higher (10%) or lower (1%) alpha level? Explain your reasoning.