Statistics 4
±1.96, the same as for a two-tailed z test at a .05 level of significance
State the critical value(s) for the following two-tailed ttest at a .05 level of significance: t(∞). ±2.228 ±1.645 not enough information is given to state the critical value(s) ±1.96, the same as for a two-tailed z test at a .05 level of significance
the population variance is unknown
As a requirement for the t test, researchers compute any type of t test with samples selected from populations in which ______. the population is the same size as the sample the population variance is known the population variance is unknown the population size is very large
all of these
Researchers state a level of significance in terms of an alpha level. The alpha level indicates ______. all of these the probability of incorrectly rejecting the null hypothesis the probability of committing a Type I error the probability value for the rejection region
ñ1.711
State the critical value(s) for a t test using a .05 level of significance in the lower tail only: t(24). ñ1.711 ñ2.064 ±2.064 ±1.711
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 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 not possible because all values were the same. The different decisions in Study 1 and Study 2 are due to an error the researcher made in the first hypothesis test. The different decisions in Study 1 and Study 2 are possible because the second test was associated with greater power to detect an effect The different decisions in Study 1 and Study 2 are not possible because the researcher tested the same hypothesis.
d = 0.33; medium effect size
A researcher reports that mean ratings of liking for some food are 0.8 ± 2.4 (M ± SD). If the null hypothesis was that the mean equals 0, then what is the effect size for this test using estimated Cohen's d? d = 3.00; large effect size There is not enough information to answer this question. d = 0.33; small effect size d = 0.33; medium effect size
the p value
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 alpha level the test statistic the p value the effect size
all of these
A point estimate is typically reported with an interval estimate. Why? Using only a point estimate is associated with low certainty. The interval estimate gives researchers a higher level of confidence. The interval estimate adds certainty to the estimate of the population mean. all of these
μ = 78
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 ______. M ≠ 78 μ = 78 μ ≠ 78 M = 78
large effect size
Based on the effect size conventions, d = 0.90 is a ______. large effect size small effect size medium effect size
to reject the null hypothesis
Given the following values: μ = 10, M = 8, σM= 0.5, conduct a one-sample z test at a .05 level of significance. What is the decision for a two-tailed test? to retain the null hypothesis to reject the null hypothesis There is not enough information since the sample size is not given.
answer significance testing
Hypothesis testing is also called ______. Type III error effect size Answer significance testing random testing
rejecting a true null hypothesis
In Step 2 of hypothesis testing, researchers state a level of significance to minimize the probability of ______. rejecting a true null hypothesis all of these inflating the power of a decision retaining a false null hypothesis
2.1
In a sample of 20 participants, a researcher estimates the 95% CI for a sample with a mean of M = 5.4 and an estimated standard error (SM) of 1.6. What is the lower confidence limit for this interval? 7.0 2.1 8.8 3.8
8.8
In a sample of 20 participants, a researcher estimates the 95% CI for a sample with a mean of M = 5.4 and an estimated standard error (SM) of 1.6. What is the upper confidence limit for this interval? 3.8 2.1 8.8 7.0
No, the same values are reported
Is a one-sample t test reported differently for one-tailed and two-tailed tests? Yes, only significant results for a two-tailed test are reported. No, the same values are reported. It depends on whether the results were significant. It can be reported differently when the effect size is large.
level of significance
The criterion for a decision regarding the value stated in a null hypothesis is set by the ______. critical value level of significance probability value p value
all of these
The t distribution is similar to the zdistribution except ______. it is characterized by "thicker" tails compared with the z distribution it is associated with scores being more likely in the tails of the distribution all of these it is associated with greater variability
critical values
When reporting the results of a one-sample z test using APA format, the ______ does not need to be reported. critical values effect size test statistic p value
The sample mean is equal to the population mean on average
Which of the following explains why point estimation can be a useful procedure to estimate a population mean? It defines the range of scores within which the population mean is likely to be contained. The sample mean is equal to the population mean on average. The sample mean is a biased estimator of the population mean.
