PSYCH 104 - Ch 8 Hypothesis Testing TEST
A Type III error is only possible when we conduct:
one-tailed tests
Which of the following will increase the power to detect an effect when it is decreased?
standard error
The power in hypothesis testing is:
the probability of rejecting a false null hypothesis the probability of rejecting a null hypothesis that is not true the probability that a randomly selected sample will show that the null hypothesis is false when the null hypothesis is in fact false
The level of significance for a hypothesis test is:
the probability to incorrectly rejecting the null hypothesis the probability of committing a Type I error the alpha level
Researchers select a sample from a population to learn more about characteristics in that sample.
False
________ measures the size of an effect in a population, whereas ______________ measures whether an effect exists in a population.
Effect size; hypothesis testing
A researcher conducts a one-independent samples z-test at a .05 level of significance. If the rejection region is placed in both tails, then what are the critical values for this hypothesis test?
±1.96
Measures of effect size allow researchers to describe:
how far scores shifted in the population the percent of variance that can be explained by a given variable
A method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample, is called:
hypothesis testing/significance testing
A researcher obtains z = 1.68 using a one-independent sample z-test. What is the decision for the hypothesis test at a .05 level of significance?
it depends on whether the test is one-tailed or two-tailed
The decision can be to retain the null:
p > .05
The decision can be to reject the null
p ≤ .05
A researcher computes a test statistic and determines that the probability of obtaining a sample mean, given that the value stated in the null hypothesis is true, is .02. The .02 refers to what value?
the p value
When a population is associated with a small effect size, what can a researcher do to increase the power of the study?
Increase the sample size (n)
Which type of test, one-tailed or two-tailed, is susceptible to the possibility of committing a Type III error?
One-tailed tests
State the two correct decisions that a researcher can make.
Retain a true null hypothesis and reject a false null hypothesis.
A researcher conducts a hypothesis test and finds that p = .0689. What is the decision for a hypothesis test at a .05 level of significance?
Retain the null hypothesis
4 Steps to Hypothesis Testing
Step 1: State the hypotheses. Step 2: Set the criteria for a decision. Step 3: Compute the test statistic. Step 4: Make a decision.
What type of error is associated with decisions to retain the null hypothesis?
Type II error
As effect size decreases, what happens to the power?
Power decreases
What type of error do we directly control?
Type I error
The effect size, power, and sample size of a study can affect the decisions we make in hypothesis testing.
True
The closer the value of a sample mean is to the value stated by the null hypothesis:
The likelihood that we reject the null hypothesis decreases
The further the value of a sample mean is from the value stated in the null hypothesis:
The likelihood that we reject the null hypothesis increases
On average, what do we expect the sample mean to be equal to?
The population mean
Nondirectional
H0 = ; H1 not=
As effect size increases, what happens to the power?
Power increases
What type of error is associated with decisions to reject the null hypothesis?
Type I error
Researchers directly control for the probability of a Type I error by stating
an alpha (α) level.
The scores for a population are normally distributed with a mean equal to 25 and standard deviation equal to 6. A researcher selects a sample of 36 students and measures a sample mean equal to 23. For this example, What is the value of Cohen's d? Is this effect size small, medium, or large?
d=(23-25)/6=0.33 medium effect size
A researcher found that the mean difference between a sample mean and a population mean was 3.2 points. If the population standard deviation equals 6.4 points, then what is the effect size for this mean difference using Cohen's d?
d=0.50 d=M-µ/σ
The level of significance in hypothesis testing is the criterion we use to
decide whether the value stated in the null hypothesis is likely to be true.
The alternative hypothesis for a lower tail critical test is given as a ________; for an upper tail critical test is given as a ________.
less than statement; greater than statement
In which step of hypothesis testing do we state that we retain or reject the null hypothesis?
make a decision
A researcher hypothesizes that parents read to their children less than the recommended 30 minutes each day. The alternative hypothesis should be:
mean time that parents spend reading to their children is less than 30 minutes
To report the results of a z-test, which of the following is not reported?
the critical value
Directional
H0 ≤ or ≥ ; H1 > or <
The criterion or level of significance in behavioral research is typically set at what probability value?
5%
A researcher selects a sample of 49 students to test the null hypothesis that the average student exercises 90 minutes per week. What is the mean for the sampling distribution for this population of interest if the null hypothesis is true?
90 minutes per week
Is the following set of hypotheses appropriate for a directional or a nondirectional hypothesis test? H0: µ = 35 H1: µ ≠ 35
A nondirectional (two-tailed) test
The decision in hypothesis testing is to retain or reject which hypothesis: null or alternative?
Null Hypothesis
A researcher conducts a one-sample z test. The z statistic for the upper-tail critical test at a .05 level of significance is zobt = 1.84. What is the decision for this test?
Reject the null hypothesis
A test statistic is associated with a p value less than .05. What is the decision for this hypothesis test?
Reject the null hypothesis
Researchers select a sample from a population to learn more about characteristics in the population from which the sample was selected.
True
A researcher incorrectly decides to reject a null hypothesis that is actually true. The researcher has committed a:
Type I error
If the null hypothesis is rejected, did we reach significance?
Yes