Unit 8: Confidence Intervals and Levels

Find the point estimate of a confidence interval? (Confidence interval (0.25 , 0.45)

• 0.25

• 0.35

• 0.45

• 0.50

A confidence interval is created by adding/subtracting the ____________ to the point estimate.

• p^

• p

• Margin of Error

• Critical Value

Which is interpreting a confidence interval?

• We are 95% confident that the interval from 0.352 to 0.548 captures the true proportion of all adults who pay for subscriptions they don't use.

• If we take many, many samples and calculate a confidence interval for each, about 95% of them will capture the true proportion of all adults who pay for subscriptions they don't use.

Which is interpreting a confidence level?

• We are 95% confident that the interval from 0.352 to 0.548 captures the true proportion of all adults who pay for subscriptions they don't use.

• If we take many, many samples and calculate a confidence interval for each, about 95% of them will capture the true proportion of all adults who pay for subscriptions they don't use.

If the confidence level goes up, the margin of error_______.

• Increases

• Decreases

If a sample size increases, the margin of error_______.

• Increases

• Decreases

Margin of error accounts for non-response bias.

• True
• False

Margin of error accounts for sampling variability.

• True
• False

Which conditions must be met when constructing a confidence interval for a proportion?

• The sample must be random

• The sample must be less than or equal to 10% of the population

• Large counts: the expected number of successes and failures must each be greater than or equal to 10.

• Central Limit Theorem: The sample must be greater than or equal to 30.

The 95% critical value for z* is 1.96.

• True
• False