Stats exam 3

John performed a one sample z test for proportions and obtained a p value of 0.35. John decided to reject the null hypothesis. What is the probability John made a Type I error?

0.35

Which of the following would increase the width of a confidence interval for a population mean A. Increase the level of confidence B. Decrease the sample standard deviation C. Increase the sample size D. All of the above

A

******£££€€A medical study was investigating if getting a flu shot actually reduced the risk of developing the flu. A hypothesis test is performed. Suppose the null hypothesis was rejected with a p value of 0.0002. The power of the test was 0.90. What type of error could be made and what is the probability of making that error?

A type II error could be made with a probability of 0.10

Researchers conducted a study and obtained a p value of 0.75. Based on this p value, what conclusion should the researchers draw?

Fail to reject the null hypothesis but do not accept the null hypothesis as true either

A confidence interval for a population mean...

Gives possible values the true population mean will be with a certain level of confidence

A critical value is...#######

How far away our sample statistic can be from the true population parameter with a certain level of confidence

Type I error

Rejecting null hypothesis when it is true

A p value is...

The probability of observing the actual result, a sample mean, for example, or something more unusual just by chance if the null hypothesis is true

***+*******Suppose x bar = 60., null hypothesis: mean = 50, alt. hypothesis: mean > 50, and the p value from a one sample test is 0.04. What does this p value mean?

The probability of getting a sample mean of 60 if the true population mean is 50 or more

Why does sample size need to be accounted for in the t distribution?

The t distribution changes for different sample sizes

When are conclusions said to be statistically significant?

When the p value is less than the given significance level

type II error

failing to reject a false null hypothesis