Statistics Proportions Inference

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

• 0.01
• 0.05
• 0.10
• 0.25

If no p^ value is given, what should you assume p^ 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

When leaving for school, you make a judgement on these hypotheses. Ho: The weather will remain dry. Ha: It will rain. What are the results of the Type I and Type II errors?

• Type I: Needlessly carry around an umbrella all day. Type II: Get drenched
• Type I: Get drenched. Type II: Needlessly carry around an umbrella all day
• Type I: Carry umbrella &  it rains. Type II: Carry no umbrella & it doesn't rain
• Type I: Get drenched. Type II: Carry umbrella & it rains

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 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