Inference for Proportions Review

If no alpha level is given, what alpha level is assumed?

• 0.01
• 0.05
• 0.10
• 0.25

If no p-hat value is given, what should you assume p-hat equals?

• 0.01

• 0.05

• 0.10

• 0.5

Which of the following hypotheses is a valid example of a 1-tailed test?

• Ho: p = 0.3, Ha: p > 0.4
• Ho: p = 0.3, Ha: p ≠ 0.3
• Ho: p^ = 0.3, Ha: p^ > 0.3
• Ho: p = 0.3, Ha: p > 0.3

A confidence interval estimate is determined from the summer earnings of a SRS of n students. All other things being equal, which of the following will result in a smaller margin of error?

• A greater confidence level
• A larger sample standard deviation
• A larger sample size
• Introducing bias into sampling

Two confidence interval estimates from the same sample are (0.72, 0.83) and (0.75, 0.81). One is at 95%, the other is at 99%. Which is which?

• (0.72, 0.83) is at 99%
• (0.72, 0.83) is at 95% 
• Need to know sample size to determine this
• Need to know standard error to determine this

Tina wants to know if the proportion of people who buy burgers is at all affected by her open mic reading. If p=0.8 before her reading, what is an appropriate set of hypotheses?

• Ho: p = 0.8
  Ha: p > 0.8
• Ho: p = 0.8
  Ha: p < 0.8
• Ho: p ≠ 0.8
  Ha: p = 0.8
• Ho: p= 0.8
  Ha: p ≠ 0.8

Which of the following is true?

• We do not use sample statistics when stating hypotheses
• P-value = 0.05 means the probability that the null is true is 0.05
• If the p-value is small enough, we can conclude that the alternate hypothesis is true
• You must examine your data prior to deciding to do a 1- or 2-tailed test

Under what conditions would it be meaningful to construct a confidence interval estimate when the data consist of the entire population?

• If the population size is large (n > 30)
• If a higher level of confidence is desired
• If the population is truly random
• Never

A credit card company would like to compare the proportion of people who have poor credit to the proportion of people who think they have poor credit. Which of the following is most appropriate?

• 1-Proportion Z-Test
• 1-Proportion Z-Interval
• 2-Proportion Z-Test
• 2-Proportion Z-Interval

A 99% confidence interval found that the true proportion of teens who drink coffee every day is in the interval (0.785, 0.831). What was the p^ value used to determine this interval? 

• 0.8
• 0.808
• 0.825
• 0.831