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A sample of n = 25 scores produces a t statistic of t = 2.062.If the researcher is using a two-tailed test,which of the following is the correct statistical decision?


A) The researcher can reject the null hypothesis with α = .05 but not with α = .01.
B) The researcher can reject the null hypothesis with either α = .05 or α = .01.
C) The researcher must fail to reject the null hypothesis with either α = .05 or α = .01.
D) It is impossible to make a decision about H0 without more information.

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For a two-tailed test with α = .05 and a sample of n = 16,the boundaries for the critical region are t = ±2.120.

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Why are t statistics more variable than z-scores?


A) The extra variability is caused by variations in the sample mean.
B) The extra variability is caused by variations in the sample variance.
C) The extra variability is caused by variations in the df value.
D) None of the other options explains the extra variability for t statistics.

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If other factors are held constant,as the sample variance increases,the estimated standard error also increases.

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Two samples from the same population both have n = 10 scores with M = 45.If the t statistic is computed for each sample,then what is the relationship between the two t values?


A) The two t statistics will be identical.
B) The sample with the larger variance will produce the larger t statistic.
C) The sample with the smaller variance will produce the larger t statistic.
D) There is no way to predict the relationship between the two t statistics.

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If two samples,each with n = 20 scores,are selected from the same population and both have the same mean (M = 53)and the same variance (s2 = 12),then they will also have the same t statistic.

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For a one-tailed test evaluating a treatment that is supposed to decrease scores,a researcher obtains t(8)= 1.90.For α = .05,the correct decision is to reject the null hypothesis.

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A researcher is using a two-tailed hypothesis test with α = .05 to evaluate the effect of a treatment.If the boundaries for the critical region are t = ± 2.080,then how many individuals are in the sample?


A) n = 22
B) n = 21
C) n = 20
D) Impossible to determine without more information

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How does sample variance influence the estimated standard error and measures of effect size such as r2 and Cohen's d?


A) Larger variance increases both the standard error and measures of effect size.
B) Larger variance increases the standard error but decreases measures of effect size.
C) Larger variance decreases the standard error but increases measures of effect size.
D) Larger variance decreases both the standard error and measures of effect size.

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If a sample of n = 16 scores is being used to make an 80% confidence interval estimate of the population mean,μ,what value(s) of t should be used?


A) t = 0
B) t = ±2.131
C) t = ±1.753
D) t = ±1.341

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A random sample with n = 20 scores has df = 19.

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A research report states "t(8)= 2.00,p > .05." For this test,r2 = 2/10.

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A sample of n = 4 scores is selected from a population with an unknown mean.The sample has a mean of M = 40 and a variance of s2 = 16.Which of the following is the correct 90% confidence interval for μ?


A) μ = 40 ± 2.353(4)
B) μ = 40 ± 1.638(4)
C) μ = 40 ± 2.353(2)
D) μ = 40 ± 1.638(2)

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Compared to a z-score,a hypothesis test with a t statistic requires less information from the population.

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Which of the following would have no effect on the width of a confidence interval?


A) Increase the sample mean
B) Increase the size of the sample
C) Increase the percentage of confidence
D) Increase the sample variance

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Under what circumstances can a very small treatment effect be statistically significant?


A) If the sample size big and the sample variance is small
B) If the sample size and the sample variance are both big
C) If the sample size is small and the sample variance is big
D) If the sample size and the sample variance are both small

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If a hypothesis test using a sample of n = 16 scores produces a t statistic of t = 2.15,then the correct decision is to reject the null hypothesis for a two-tailed test with  = .05.

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If two samples from the same population are the same size and have the same mean,then they will have the same t statistic.

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A sample with a mean of M = 40 and a variance of s2 = 20 has an estimated standard error of 1 point.How many scores are in the sample?


A) 4
B) 5
C) 20
D) 21

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The sample mean will always be exactly in the center of a confidence interval that is estimating the value of the population mean.

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