Interpreting and Constructing Confidence Interval

Suppose that $51,759 was the median income for all households in 2012. Does the interval ($51,484, $52,394) provide convincing evidence that the median household income increased in 2013? 

• Yes

• No

What is the format for interpreting a confidence interval? 

• The interval from ___ to ___ captures the true mean in context.

• C% of samples of the same size taken from the same population will capture the parameter in question

• There is convincing evidence that C% gives the interval (___, ___) capturing the parameter in question.

• We are C% confident that the interval from ___ to ___ captures the [parameter in context].

What can you do to reduce the margin of error? 

• increase the confidence level

• decrease the confidence level

• increase sample size

• decrease sample size

What is the critical value z* for a 99% confidence interval? 

• -2.58

• 1.96

• -1.64

• 2.58

Given the interval (1.2, 1.8), what is the point estimate and the margin of error? 

• 1.5, 0.6

• 1.5, 0.3

• 1.2, 0.3

• 1.2, 0.6

What critical value t* is used in constructing a 99% confidence interval based on n = 12 randomly selected observations. 

• 3.106

• 3.055

• 2.58

• 1.96

Increasing the sample size __________ the confidence interval. 

• increases

• decreases

• does not affect

• there is not enough evidence to determine the answer

Interpreting the 99% confidence interval yields the conclusion that we are 99% confident that the interval from 118 to 130 bushels per acre captures the ____ ____ _____ of this variety of corn in all possible plots.

Give the 95% confidence interval.

• (0.345, 0.397)

• (0.206, 0.265)

• (0.289, 0.372)

• (0.258, 0.302)

In interpreting the confidence interval, we are 95% confident that the interval from 0.258 to 0.302 contains the ____ __________ of adults who feel unemployment should be extended 6 months.