Exam 8: Introduction to Hypothesis Testing

A two-tailed hypothesis test is being used to evaluate a treatment effect with α = .05.If the sample data produce a z-score of z = 2.24,then what is the correct decision?​

A researcher administers a treatment to a sample of participants selected from a population with µ = 80.If the researcher obtains a sample mean of M = 88,given the same sample size,which combination of factors is most likely to result in rejecting the null hypothesis?​

A measure of effect size is intended to provide a measurement of the absolute magnitude of a treatment effect.

Even if a treatment has an effect,it is still possible to obtain a sample mean that is very similar to the original population mean.What outcome is likely if this happens?​

A researcher is conducting an experiment to evaluate a treatment that is expected to increase the scores for individuals in a population.If the researcher uses a one-tailed test with a = .01,then which of the following correctly identifies the critical region?​

The value obtained for Cohen's d is independent of the sample size.

What is the relationship between the alpha level,the size of the critical region,and the risk of a Type I error?​

When is there a risk of a Type II error?​

A Type I error occurs when a treatment has no effect but the decision is to reject the null hypothesis.

A researcher administers a treatment to a sample of n = 16 selected from a population with m = 40 and s = 8.If the sample mean after treatment is M = 42,then Cohen's d = 1.00.

Define the critical region for a hypothesis test,and explain how the critical region is related to the alpha level.

Decreasing the alpha level from α = .05 to α = .01 ____.​

The term error is used in two different ways in hypothesis testing: a Type I error (or Type II)and the standard error. a. What can a researcher do to influence the size of the standard error? Does this action have any effect on the probability of a Type I error? b. What can a researcher do to influence the probability of a Type I error? Does this action have any effect on the size of the standard error?

There is always a possibility that the decision reached in a hypothesis test is incorrect.

Which combination of factors will increase the chances of rejecting the null hypothesis?​

A researcher administers a treatment to a sample of participants selected from a population with µ = 80.If a hypothesis test is used to evaluate the effect of the treatment,which combination of factors is most likely to result in rejecting the null hypothesis?​

If other factors such as sample size,alpha level,and population standard deviation are held constant,the larger the size of the treatment effect,the greater the power of the hypothesis test.

If all other factors are held constant,increasing the sample size from n = 25 to n = 100 will increase the power of a statistical test.

A sample of n = 25 individuals is selected from a population with µ = 80 and a treatment is administered to the sample.What is expected if the treatment has no effect?​

A researcher would like to determine whether a new tax on cigarettes has had any effect on people's behavior.During the year before the tax was imposed,stores located in rest areas on the state thruway reported selling an average of µ = 410 packs per day with σ = 60.The distribution of daily sales was approximately normal.For a sample of n = 9 days following the new tax,the researcher found an average of M = 386 packs per day for the same stores. a. Is the sample mean sufficient to conclude that there was a significant change in cigarette purchases after the new tax. Use a two-tailed test with α = .05. b. If the population standard deviation was σ = 30, is the result sufficient to conclude that there is a significant difference? c. Explain why the two tests lead to different outcomes.