Question

Given p⎯⎯1p¯1 = 0.81, n1n1 = 469, p⎯⎯2p¯2 = 0.85, n2n2 = 364. (You may find it useful to reference the appropriate table: z table or t table)


a. Construct the 99% confidence interval for the difference between the population proportions. (Negative values should be indicated by a minus sign. Round intermediate calculations to at least 4 decimal places and final answers to 2 decimal places.)

b. Is there a difference between the population proportions at the 1% significance level?

• Yes, since the confidence interval includes the value 0.

• Yes, since the confidence interval does not include the value 0.

• No, since the confidence interval includes the value 0.

• No, since the confidence interval does not include the value 0.

Answer 1

a) A 99% confidence level has significance level of 0.01 and critical value is,

Point estimate of the difference between the population proportion is,

Standard error of the difference between the population proportion is,

The 99% confidence interval for the difference between the population proportion is,

99% confidence interval is (-0.11, 0.03)

b) There is no difference between the population proportions at the 1% significance level.

Answer: No, since the confidence interval includes the value 0.