Question

A simple random sample of 700 individuals provides 300 Yes responses.

a. What is the point estimate of the proportion of the population that would provide Yes responses (to 3 decimals, if needed)?

b. What is your estimate of the standard error of the proportion (to 4 decimals)?

c. Compute the 95% confidence interval for the population proportion (to 3 decimals).
( , )

Answer 1

a) point estimate of the proportion of the population, p = x/n = 300 / 700 = 0.43

b) estimate of the standard error of the proportion = sqrt(n * p * (1 - p))

                                                                               = sqrt(700 * 0.43 * (1 - 0.43))

                                                                               = 13.09

c)  

Z for 95% confidence interval = Z0.975 = 1.96

confidence interval =

=

=

= (0.4113 , 0.4487)