Question

A recent Pew Research poll surveyed U.S. residents to ask about their use of social media. Of the 156 respondents aged 18 to 22 who use Facebook, 30.7% stated that they updated their Facebook status at least once per day.

Is .307 the true proportion parameter p or the point estimate p̂?

A. true proportion p

B. point estimate p̂

Compute the standard error of the sample proportion, i.e. the standard deviation of the sample proportion.

A. 0.032

B. 0.043

C. 0.025

D. 0.037

Compute the 95% confidence interval for the true proportion. (Use the rounded value for the standard error)

A. [.246, .368]

B. [.229, .385]

C. [.217, .397]

D. [.234, .380]

Interpret the confidence interval computed above:

I am_____% confident that the true _____ of all Facebook users aged 18 to 22 who update their Facebook status at least once per day ____ those two values.

Why can a confidence interval for a population parameter not be interpreted in terms of probability?

A. Because the population parameter is not a random variable.

B. Because the sample size is not large enough.

C. Because the population parameter is a known value.

D. Because probability is not related to statistics.

Answer 1

B. point estimate p̂

standard error:D. 0.037

95% confidence interval : D. [.234, .380]

I am_95% confident that the true proportion of all Facebook users aged 18 to 22 who update their Facebook status at least once per day falls between  those two values.

A. Because the population parameter is not a random variable.