PSYC 2317 Chapter 9 Quiz

PSYC 2317 CHAPTER 9 QUIZ Question 1 5 out of 5 points A psychologist is interested in whether working memory is influenced by sleep loss. The psychologist administers a measure of working memory to a group of subjects at 8 A.M. on Day 1 of the study and then again at 8 A.M. on Day 2 of the study, after keeping the subjects awake the entire night. Does sleep loss affect working memory? What statistical analysis should be performed to answer this question? Selected Answer: dependent-samples t test Answers: single-sample t test z test standard deviation analysis dependent-samples t test Question 2 5 out of 5 points The t distribution allows researchers to generalize from Selected Answer: one sample to a larger population. Answers: one population to a larger sample. one sample to a larger population. one sample to another. one statistical test to another. Question 3 5 out of 5 points Why does one divide by N – 1 rather than by N when estimating a population standard deviation from the sample standard deviation? Selected Answer: Because the sample standard deviation is likely to be an imprecise estimate, we allow the error of the estimate (the standard deviation) to be larger by dividing the sum of squares by a smaller number. Answers: Because the sample standard deviation is likely to be an imprecise estimate, we allow the error of the estimate (the standard deviation) to be larger by dividing the sum of squares by a smaller number. The sample standard deviation is a superior estimate of the variability in the population than is the population standard deviation. We typically have to throw out at least one data point in any given study, so the N – 1 allows us to account for that. Because the population is always smaller than the sample, we must divide by a smaller number. Question 4 5 out of 5 points What is the formula for the paired-samples t test? Selected Answer: Answers: Question 5 5 out of 5 points The t statistic indicates the: Selected Answer: distance of a sample mean from the population mean in terms of estimated standard error. Answers: number of standard deviations an individual score is from the sample mean. number of standard deviations a sample mean is from the population mean. distance of two sample means from a single population mean. distance of a sample mean from the population mean in terms of estimated standard error. Question 6 5 out of 5 points At a sample size of infinity, the t distribution: Selected Answer: