Posted: December 14th, 2022

The __________ is a hypothesis-testing procedure in which there are two separate groups of people tested

Question 1 of 251.0 PointsThe __________ is a hypothesis-testing procedure in which there are two separate groups of people tested and the population variance is not known.A.t test for dependent meansB.t test for a single sampleC.t test for independent meansD.t test for repeated measuresReset SelectionQuestion 2 of 251.0 PointsWhich of the following is an example of a situation in which you could conduct a t test for independent means?A.A comparison of the SAT scores of a group of 10 students who completed a special SAT preparation course compared to how people do on the SAT in general.B.A comparison of scores of participants in a memory study in which one group learns the words in alphabetical order and another group learns the words in order of word length.C.A comparison of participants’ scores on a skills test before and after attending a training session for improving the skill.D.None of the above would be suitable for a t test for independent means.Reset SelectionQuestion 3 of 251.0 PointsThe comparison distribution for a t test for independent means is a:A.distribution of differences between meansB.Z distribution (i.e., a normal curve)C.distribution of difference scoresD.distribution of proportional variance scoresReset SelectionQuestion 4 of 251.0 PointsA “distribution of differences between means” can be thought of as a distribution of as:A.difference scores, in which the difference scores are found by subtracting a series of sample means from the population meanB.the differences you find when you use several methods, in sequence, of estimating the population meanC.the differences you get when you repeatedly draw a sample mean from one population and a sample mean from another population and subtract one mean from the otherD.the differences between a single sample from Population 1 and all possible samples from Population 2Reset SelectionQuestion 5 of 251.0 PointsYou conduct a t test for independent means and reject the null hypothesis. This means that:A.the samples were from populations that were actually dependent rather than independentB.the variance of one sample is so much larger than the variance of the other sample that you decide that the variances of the parent populations must not have been the sameC.the mean of one sample is so far from the mean of the other sample that you decide the samples must come from populations with different meansD.the mean of one sample is statistically the same as the mean of the other sample, so they probably come from populations with equal meansReset SelectionQuestion 6 of 251.0 PointsWhen conducting a t test for independent means, a typical research hypothesis might be:A.the mean of Population 1 is greater than the mean of Population 2B.the mean of Sample 1 is greater than the mean of Sample 2C.the mean of Sample 1 is the same as the mean of Sample 2D.the mean of Population 1 is the same as the mean of Population 2Reset SelectionQuestion 7 of 251.0 PointsAll of the following are true for both the t test for independent means AND the t test for dependent means, EXCEPT:A.population variances are estimated from the information in the sample of scores actually studiedB.pretest–posttest experimental designs are commonC.the population means are unknownD.the sample scores (in some form) are eventually compared to a t distributionReset SelectionQuestion 8 of 251.0 PointsWhen determining the pooled population variance estimate in a t test for independent means:A.the variance of at least one of the original populations must be known (as opposed to estimated), but the other can be estimated from sample scoresB.the variance of BOTH of the original populations must be known, as opposed to estimatedC.the estimates based on each of the samples are averaged in such a way as to give more influence to the estimate based on more participantsD.the scores from both samples are combined to form a single sample, and the estimated variance is figured in the usual way, but using this combined sampleReset SelectionQuestion 9 of 251.0 PointsIn a t test for independent means, the weighted average of the estimates of the population variance from two samples is known as the:A.estimate of sample standard deviationB.primed estimate of population standard deviationC.pooled estimate of population varianceD.pooled estimate of degrees of freedomReset SelectionQuestion 10 of 251.0 PointsIn a t test for independent means, the square root of the variance of distribution of differences between means is known as the:A.overestimate of population varianceB.pooled estimate of population standard deviationC.variance of the distribution of differences between meansD.standard deviation of the distribution of differences between meansReset SelectionQuestion 11 of 251.0 PointsWhich of the following is the best way to reduce the variances in the distributions of means when conducting a t test for independent means?A.Increase the size of the samplesB.Raise the study’s level of significanceC.Use the true population varianceD.Treat the two samples as one sampleReset SelectionQuestion 12 of 251.0 PointsWhen conducting a t test for independent means, once the variances are known for each of the distributions of means, the variances can be added together to give the:A.pooled estimate of the population varianceB.variance of the distribution of differences between meansC.t scoreD.power of the studyReset SelectionQuestion 13 of 251.0 PointsThe variance of a distribution of differences between means equals:A.the difference between the variances of the two distributions of meansB.the sum of the variances of the two distributions of meansC.the difference between the two estimated population variancesD.the sum of the two estimated population standard deviationsReset SelectionQuestion 14 of 251.0 PointsThe comparison distribution for a t test for independent means is a t distribution (as opposed to a normal curve) because:A.tables are not available for the normal curveB.the population variance is estimatedC.Z distributions were not used at the time the t test for independent means was inventedD.there are more degrees of freedom for a single sample than for when you use two samplesReset SelectionQuestion 15 of 251.0 PointsWhen using a t table, the degrees of freedom you should use for a t test for independent means is the:A.degrees of freedom for Sample 1 divided by the total degrees of freedom for both samplesB.average of the degrees of freedom for the two samplesC.sum of the two sample sizes, minus oneD.sum of the two samples’ degrees of freedomReset SelectionQuestion 16 of 251.0 PointsEach of the following is part of conducting a t test for independent means, EXCEPT:A.difference scores are found for each participantB.the population variances are estimatedC.a comparison is made against a t distributionD.the variance of the distribution of differences between means is figuredReset SelectionQuestion 17 of 251.0 PointsWhen conducting a t test for independent means:A.you assume the medians of the two populations are equalB.you reject the null hypothesis if the t score is more extreme than the cutoff t scoreC.you should use only the .01 significance level because of the greater power compared to a t test for dependent meansD.all of the aboveReset SelectionQuestion 18 of 251.0 PointsMany computer programs provide two sets of results for the t test for independent means. The standard method assumes that the population variances are __________ ; an alternative procedure takes into account that the population variances may be __________.A.negatively skewed; positively skewedB.skewed; normally distributedC.equal; unequalD.divisible by one another; highly skewedReset SelectionQuestion 19 of 251.0 PointsThe effect size for the t test for independent means is the difference between the sample means divided by the:A.pooled estimate of the population SDB.SD of the distribution of differences between meansC.SD of difference scoresD.variance of difference scores for the populationReset SelectionQuestion 20 of 251.0 PointsFor a study using a t test for independent means, with any given total number of participants, power is greatest when the participants are divided into __________ groups.A.2 equalB.3 equalC.2 unequalD.3 unequalReset SelectionQuestion 21 of 251.0 PointsFor a study using a t test for independent means, the approximate number of participants needed for 80% power for an estimated small effect size and using a one-tailed test is:A.50B.64C.310D.393Reset SelectionQuestion 22 of 251.0 PointsSuppose you carry out a study using a t test for independent means. The number of participants in each group is 40 and you conduct a one-tailed test. What would be the approximate level of power if you anticipated a medium effect size? (Consult the power table 9-4).A..07B..72C..97D..29Reset SelectionQuestion 23 of 251.0 PointsSuppose you carry out a study using a t test for independent means. The number of participants in each group is 50 and you conduct a two-tailed test. What would be the approximate level of power if you anticipated a small effect size? (Consult the power table 9-4).A..53B..80C..60D..17Reset SelectionQuestion 24 of 251.0 PointsIn an experiment involving 50 participants, which study would have the most power?A.A study with 5 in the experimental group and 40 in the control groupB.A study with 40 in the experimental group and 10 in the control groupC.A study with 25 in the experimental group and 25 in the control groupD.All would have the same power because power depends on the total number of participants; how they are divided between groups makes no difference.Reset SelectionQuestion 25 of 251.0 PointsIn a t test for independent means, when the number of scores in the two groups differs, the __________ is used as the equivalent of each group’s sample size when determining power.A.power coefficientB.pooled estimateC.harmonic meanD.independent t scoresReset Selection

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