Statistics Post Test #8

A population has a mean of 75 and a standard deviation of 15. You randomly sample nine people from the population. What is the likelihood that the sample mean will fall between 70 and 80?

68%

Your p value is .03 and you chose your α level to be .05. What kind of error could you be making?

Type I error

A researcher conducts a study and fails to reject the null hypothesis. What kind of error could he be making?

Type II error

Which of the following statement is an example of two-tailed hypothesis?

Vitamin C changes people's mood.

If you are testing a(n) ______ hypothesis, then the critical region will be ______ when α= .05.

one-tailed; 5%

You make a Type I error when you ______.

reject H0 when it is true

If your p value is 0.15 and you have chosen α of .10, then a statistical decision is to ______.

retain the null hypothesis

It is possible for your study to be statistically ______ without having much ______.

significant; importance

The denominator of one-sample z test is also known as ______.

standard error

When you reject a null hypothesis, you could be making a Type II error.

False

You can prove an alternative hypothesis.

False

If your p value from the study falls into a critical region, then the ______ hypothesis is ______.

null; rejected

If you chose the α level of .01, then which of the following p value will allow you to conclude that your result is statistically significant?

0.05

The conventional level of α in behavioral science is ______.

0.05

A population has a mean of 75 and a standard deviation of 15. You randomly sample nine people from the population, and the mean of the nine people was 80. What is the zscore of your sample mean?

1.0

Even if the population distribution is unknown, we can assume that the shape of the distribution of sample means is approximately normal if sample size is greater than or equal to ______.

30

A population has a mean of 75 and a standard deviation of 15. If you randomly sample nine people from the population, the standard error will be equal to ______.

5.0

A researcher states an alternative hypothesis that the exercise improves physical health. Which is a possible null hypothesis corresponding to this alternative hypothesis?

Exercises worsens or has not impact on physical health.

As power increases, the Type II error also increases.

False

As sample size increases, the standard error decreases.

False

You can directly manipulate the Type I error rate by changing the α levels.

True

Central limit theorem indicates that as the sample increases, the distribution of sample means would ______.

approach a normal distribution

Decreasing the α level from .05 to .01, then the likelihood of type I error ______.

decreases

Increasing the sample size ______ the sampling error, which will ______ the Type II error.

decreases; decreases

A standard error of the mean is a standard deviation of a ______.

distribution of sample means