psych 221 exam 2 Questions & Answers Already Graded A +

Which of the following accurately describes a hypothesis test - Answer-An inferential technique that uses the data from a sample to draw inferences about a population Which of the following statistics are examples of descriptive statistics? - Answer-M and SD µ and s range and variance Which set of characteristics will produce the smallest value for the estimated standard error? - Answer-A large sample size and a small sample variance What is measured by the numerator of the z-score test statistic? - Answer-The actual distance between M and µ A researcher selects a sample and administers a treatment to the individuals in the sample. If the sample is used for a hypothesis test, what does the null hypothesis (H0) say about the treatment? - Answer-The treatment has no effect on the scores. A researcher conducts a hypothesis test using a sample from an unknown population. If the one-sample t statistic has df = 30, how many individuals were in the sample? - Answer-n = 31 When n is small (less than 30), how does the shape of the t distribution compare to the normal distribution? - Answer-It is flatter and more spread out than the normal distribution. Which of the following accurately describes the critical region? - Answer-Outcomes with a very low probability if the null hypothesis is true If a hypothesis test produces a z-score in the critical region, what decision should be made? - AnswerReject the null hypothesisWith α = .05 and df = 8, the critical values for a two-tailed t test are t = ±2.306. Assuming all other factors are held constant, if the df value were increased to df = 20, what would happen to the critical values for t? - Answer-They would decrease (move closer to zero). Which of the following best describes a Type I error? - Answer-False positive If an effect is true in reality, but the researcher fails to find evidence for it in their sample, what error has been made? - Answer-A Type II error If other factors are held constant, what is the effect of increasing the sample size on hypothesis testing? - Answer-It will decrease the estimated standard error and increase the likelihood of rejecting H0. The denomentor in the formula for a one-sample t-test and an independent sample t-test are calculated differently, but conceptually are the same - estimated standard error. - Answer-true A one-sample t-test allows the researcher to determine whether the means in the experimental and control group differ. - Answer-false If a hypothesis test leads to rejecting the null hypothesis, it means that the sample data failed to provide sufficient evidence to conclude that the treatment has an effect. - Answer-false The results of an independent-samples t-test are reported as follows: t(15) = 2.70, p < .05. Based on this report, how many individuals were in the sample? - Answer-17 Compared to a z-score, a hypothesis test with a t statistic requires more information from the sample. - Answer-true If two samples from the same population are the same size and have the same mean, then they will have the same t statistic. - Answer-false Which of the following is a fundamental difference between the t statistic and a z-score? - Answer-The t statistic uses the sample variance in place of the population variance.In Step 2, what are the t values that create the critical region? - Answer-less than -1.98 and more than 1.98 In Step 3, what type of t-test is this? - Answer-independent t-test In Step 3, what value goes in the denominator of the t test formula? - Answer-0.2 In Step 3, what is the t-statistic? - Answer--2.5 In Step 4, what is your conclusion from the hypothesis test? - Answer-reject the null