Stats Ch 7
A researcher conducts a study, but has low power to detect an effect. Which of the following is one way in which the research can increase power
increase the sample size
What are the two decisions that researchers can make in hypothesis testing
retain or reject the null hypothesis
A researcher obtains z = 1.45 for a one-sample z test. What is the decision for this test at a .05 level of significance
to retain the null hypothesis
The probability of committing a Type I error is stated by ______ and the probability for committing a Type II error is stated by
alpha, beta
Based on the effect size conventions, d = 0.60 is a
medium
What is the typical level of significance for a hypothesis test in behavioral research
.05
A measure of the size of an effect in a population is called
effect size
_ allows researchers to describe (1) how far mean scores have shifted in the population or (2) the percentage of variance that can be explained by a given variable
effect size
in hypothesis testing, a researcher can never
prove his or her hypothesis correct
Hypothesis testing is also called
significance testing
A researcher directly controls for the probability of a ______, but does not directly control for the probability of a
type 1 error, type 2 error
Which of the following is a scenario in which increasing sample size will increase power
.when the effect size is small b.when the effect size is large c.when the probability of a Type I error is small d.all of these
A professor gives an exam in which the mean score is 78 points. She gives another exam to test whether or not scores change. In this example, the null hypothesis is
mu=78
A researcher reports the following result for a one-sample z test at a .05 level of significance: z = 1.88, p = -.06 (d = .25). Is this result significant
no, the decision is to retain the null hypothesis
Is a one-sample z test reported differently for one-tailed and two-tailed tests?
no, the same values are reported
Which of the following statements regarding the null hypothesis is true
The null hypothesis always makes statements about a population parameter.
In Step 2 of hypothesis testing, researchers state a level of significance to minimize the probability of
rejecting a true null hypothesis
A researcher reports that scores were higher than the mean in the population, z = 1.60, p = .05 (d = .14). If this was a test at a .05 level of significance, then what value must be incorrectly reported
the p value
If a researcher obtains a null finding, then what is the decision
they correctly retained the null hypothesis
A researcher obtains z = -6.45. What is the decision for a one-tailed test, upper-tail critical, at a .05 level of significance
to retain the null hypothesis
The one-sample z test is a hypothesis test used to test hypotheses
concerning a single population with a known variance
When reporting the results of a one-sample z test using APA format, the ______ does not need to be reported
critical values
A method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample, is called
hypothesis testing
Which of the following is not one of the four steps to hypothesis testing
identify the hypothetical data
Increasing the sample size will
increase the power of the decision
in hypothesis testing a researchers decision is
is based on a probability b.depends on the level of significance for a hypothesis test c.can be to retain or reject the null hypothesis d.all of these
Which of the following best describes the p value
it is a conditional probability
Based on the effect size conventions, d = 0.90 is a
large effect size
Suppose a researcher wants to make sure that the probability of committing a Type I error is less than 5%. How can the researcher control for this
set the alpha level at .05
Based on the effect size conventions, d = 0.18 is a
small effect size
The first step to hypothesis testing requires that a researcher
state the hypothesis
The power of the decision-making process is
the likelihood of rejecting a false null hypothesis
A researcher obtains z = 2.04 for a one-sample z test. What is the decision for this test at a .05 level of significance
to reject the null hypothesis
A professor finds that the average SAT score among all students attending his college is 1150 150 ( ). He polls his class of 25 students and finds that the average SAT score is 1,200. Suppose he computes a one-sample z test at a .05 level of significance. What is his decision
to reject the null hypothesis for an upper-tailed test, but to retain the null hypothesis for a two-tailed test
Given the following values: = 6.0, M = 7.6, n = 36, = 6, conduct a one-sample z test at a .05 level of significance. For a one-tailed test, upper-tail critical, what is the decision
to retain the null hypothesis
When a researcher decides to retain the null hypothesis because the rejection region was located in the wrong tail, this is called a
type 3 error
If the value of the test statistic is in the rejection region, then
.p < .05 b.the decision is to reject the null hypothesis c.the value of the test statistic is larger than the critical value d.all of these
A researcher obtains z = 3.98 for a one-sample z test. If her decision is to retain the null hypothesis, then what do you know about her decision
Her decision resulted in a type 3 error
A researcher obtains z = 1.80 for a one-sample z test. What is the decision for this test at a .05 level of significance
It depends on whether the test is one-tailed or two-tailed
The criterion for a decision regarding the value stated in a null hypothesis is set by the
Level of significance
A researcher reports that the size of an effect in some population is d = 0.88. Which of the following is an appropriate interpretation for d
Mean scores shifted 0.88 standard deviations in the population
A researcher selects a sample of 36 students from a school population with a mean IQ of 100 and standard deviation of 12. She determines that the mean IQ in this sample is 104. Assuming she computes a one-sample z test at a .05 level of significance, what is the decision for a two-tailed test?
Reject the null hypothesis; IQ scores in this sample are significantly higher than those in the population
A researcher computes a one-sample z test in two studies. Both studies used the same alpha level, placed the rejection region in both tails, and measured the same sample mean. The researcher selects a sample of 30 participants in Study 1 and decides to retain the null hypothesis. She selects a sample of 60 participants in Study 2 and decides to reject the null hypothesis. Which of the following is the best explanation for why the decision was different in Study 1 and Study 2
The different decisions in Study 1 and Study 2 are possible because the second test was associated with greater power to detect an effect.
A researcher reports that the standard deviation in Population A is = 2.3 and the standard deviation in Population B is = 4.3. Which population is associated with the highest power to detect an effect?
population A
A researcher reports that the size of an effect in Population A is d = 0.10 and the effect size in Population B is d = 0.34. Which population is associated with greater power to detect an effect
population B
A researcher computes a test statistic and finds that the p value for this test is .03. What does this result mean
There is a 3% likelihood of obtaining the test statistic value, if the null were true
Given the following values: mu= 10, M = 8, sigma= 0.5, conduct a one-sample z test at a .05 level of significance. What is the decision for a two-tailed test
reject the null hypothesis
A researcher conducts two studies. Each study was a one-sample z test. Both studies placed the rejection region in both tails and measured the same sample mean. The beat level in Study 1 was larger than the beta level used in Study 2. Which study is associated with greater power to detect an effect
study 2
Researchers state a level of significance in terms of an alpha level. The alpha level indicates
.the probability of committing a Type I error b.the probability of incorrectly rejecting the null hypothesis c.the probability value for the rejection region d. all of these
A researcher believes that increasing attention given to children will improve mean academic performance. Therefore, the alternative hypothesis should be
mean academic performance will increase
