BESC 3010 Ch8
If a sample's mean really is different from the comparison population's mean, then what is the easiest way to make sure that the null hypothesis would be rejected?
Getting as large a sample as possible
If a research conducts a z-test and does not reject the null hypothesis, then...
None of the other choices is correct.
If a researcher believes that the null hypothesis is false and wants to have the greatest chance of rejecting it with their study, then which of the following would make it more likely that the null hypothesis would be rejected?
increasing n
n a two-tailed or non-directional test, if the critical value has a greater absolute value than the observed (or test) value does, the the null hypothesis...
is not rejected (i.e., retained).
When calculating an effect size for the z-test...
it is most common to use Cohen's d
A researcher who wants to use a z-test to compare a sample mean to a population mean must first...
know the population standard deviation.
In order to compute a one-sample z-test you must.
know the population standard deviation.
If a researcher is using an critical value of \pm 1.96 for a z-test and gets an observed z (i.e., test value) of +0.55 for a sample of n = 40, then the researcher should...
retain (i.e., fail to reject) the null hypothesis
If a researcher is using an alpha of .05 for a z-test and gets an observed (or test) p-value of .23, then the researcher should...
retain (i.e., fail to reject) the null hypothesis.
If a researcher is using an critical value of ±1.96 for a z-test and gets an observed (or test) z of -1.73, then the researcher should...
retain (i.e., fail to reject) the null hypothesis.
If a researcher used a one-sample z-test to determine whether an experimental group was different from a general population, what she would actually be testing is...
whether their means are different.
Which level of alpha for a hypothesis test has the lowest risk of a Type I error?
.01
When choosing a level of alpha for a hypothesis test, unless you have a compelling reason to do otherwise, you should use...
.05
If a person's blood sample tests positive for a disease when, in fact, the person does not have the disease, then...
A type I error has occurred
When the mean of the population that a sample comes from does not differ from the general population but the sample mean is nonetheless significantly different from the general population, then...
A type I error has occurred
Imagine two studies that are identical in every respect except the size of their samples. Sample A has an effect size of d = .20 and a p-value of .03. Sample B has an effect size of d = .20 and a p-value of .005. Which sample likely had the smaller sample size?
Sample A
Imagine two studies that are identical in every respect except the size of their samples. Sample A has an effect size of d = .40 and p-value of .001. Sample B also has an effect size of d = .40 but a p-value of .10. Which sample likely had the larger sample size?
Sample A
Imagine two studies that are identical in every respect except their effect sizes. Sample A has a sample size of n = 80 and a p-value of .01. Sample B has a sample size of n = 80 and a p-value of .10. Which sample likely had the larger effect size?
Sample A
What does it mean when the result of a z-test is called "statistically significant"?
The alpha value was greater than the p-value
A Type I error is also called...
a false positive
Imagine that a researcher is interested in whether residents in his local area have higher levels of well-being than the national average. What would be an appropriate alternate hypothesis for a one-tailed or directional z-test for this test?
ocal residents average > national average
If a researcher wants to test whether an experimental group is different from the general population, the she would test...
the null hypothesis of no difference between the group and the population.
If you draw a picture of the null distribution with the critical values and regions of rejection marked, then the alpha level is represented by...
the proportion of the distribution in the regions of rejection.
The z-test is appropriate when...
the researcher knows the population mean and variance/standard deviation
If a researcher is using alpha = .01 and gets a p-value for the z-test of p = .005, then...
the researcher should conclude that the results are unlikely to occur by chance if the null hypothesis is true.
If a researcher is using alpha = .05 and gets a p-value for the z-test of p = .02, then...
the results are unlikely to occur by chance if the null hypothesis is true.
A Type I error occurs when...
the sample data lead us to reject a null hypothesis that is true.
A Type II error occurs when...
the sample data lead us to retain (i.e., fail to reject) a null hypothesis that is false.
If a researcher is comparing a sample mean to a population mean and gets Cohen's d = -2.0, this means that...
the sample mean is two standard deviations below the population mean.
When calculating an effect size for the z-test...
the sample size is irrelevant.
