PY292 Intro to Hypothesis Testing

If all the possible random samples of size n = 25 are selected from a population with μ = 90 and σ = 20, and the mean is computed for each sample, then what shape is expected for the distribution of sample means?

• 1. The sample means tend to form a normal-shaped distribution.

• 1. The distribution of sample means will have the same shape as the population distribution.

• he sample will be distributed evenly across the scale, forming a rectangular-shaped distribution.

• There are thousands of possible samples and it is impossible to predict the shape of the distribution.

The mean and standard deviation of a population are 200 and 20, respectively. Sample size is 25. 
What is the mean of the sampling distribution?

• 200
• 16
• 25
• 4

 Scores from a questionnaire measuring social anxiety form a population with a mean of μ = 50 and a standard deviation of σ = 10. What is the probability of obtaining a sample mean greater than M = 53 for a random sample of n = 4 people?

• 27.43%

• 40.08%

• 60.77%

• 72.91%

In general terms, what is a hypothesis test?

• 1. A descriptive technique that allows researchers to describe a sample.

• 1. A descriptive technique that allows researchers to describe a population.

• 1. An inferential technique that uses the data from a sample to draw inferences about a population.

• 1. An inferential technique that uses information about a population to make predictions about a sample.

Which of the following accurately describes the critical region for a hypothesis test?

• 1. Outcomes that have a very low probability if the null hypothesis is true.

• 1. Outcomes that have a high probability if the null hypothesis is true.

• 1. Outcomes that have a very low probability regardless of whether the null hypothesis is true.

• 1. Outcomes that have a high probability regardless of whether the null hypothesis is true.

The psychology department is gradually changing its curriculum by increasing the number of online course offerings. To evaluate the effectiveness of this change, a random sample of n = 36 students who registered for Introductory Psychology is placed in the online version of the course. At the end of the semester, all students take the same final exam. The average score for the sample is M = 76. For the general population of students taking the traditional lecture class, the final exam scores form a normal distribution with a mean of μ = 71 and a standard deviation of σ = 12. The department conducts a hypothesis test with α = .05. Which of the following correctly describes the outcome of the hypothesis test?

• Reject the null hypothesis because z = 2.50 which is in the critical region.

• Accept the null hypothesis because z = 2.50, which is outside of the critical region.

• Fail to reject the null hypothesis because z = 0.42, which is not in the critical region.

• ail to accept the alternative hypothesis because z = 0.42, which is inside of the critical region.

What does a Type II error mean?

• A researcher has falsely concluded that a treatment has an effect.

• A researcher has correctly concluded that a treatment has no effect.

• A researcher has falsely concluded that a treatment has no effect.

• A researcher has correctly concluded that a treatment has an effect.

What is the consequence of increasing the alpha level (for example, from .01 to .05)?

• It will increase the likelihood of rejecting the null hypothesis, and increase the risk of a Type I error.

• It will decrease the likelihood of rejecting the null hypothesis and increase the risk of a Type I error.

• 1. It will increase the likelihood of rejecting the null hypothesis and decrease the risk of a Type I error.

• 1. It will decrease the likelihood of rejecting the null hypothesis and decrease the risk of a Type I error.

A research report includes the statement, “z = 1.18, p > .05.” What happened in the hypothesis test?

• The obtained sample mean was very unlikely if the null hypothesis is true, so the null was rejected.

• 1. The obtained sample mean was very likely if the null hypothesis is true, so the null was rejected.

• 1. The obtained sample mean was very unlikely if the null hypothesis is true, and the test failed to reject the null.

• 1. The obtained sample mean was very likely if the null hypothesis is true, and the test failed to reject the null.

A hypothesis test involves a comparison of which two elements?

• research results from a sample and a hypothesis about a population

• research results from a population and a hypothesis about a sample

• research results from a population and a hypothesis about the population

•  results from a sample and a hypothesis about the sampl