stats exam 2 October 29

what class is the test on

stats

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 ______. A. μ ≠ 78 B. M ≠ 78 C. μ = 78 D. M = 78

c

. In a normal distribution, 50% of all data ______. A. fall above the mean B. fall below the median C. fall above and below the mode D. all of these

d

Hypothesis testing is also called ______. A. Type III error B. random testing C. effect size D. significance testing

d

If the value of the test statistic is in the rejection region, then ______. A. p < .05 B. the decision is to reject the null hypothesis C. the value of the test statistic is larger than the critical value D. all of these

d

Which of the following is not one of the four steps to hypothesis testing? A. state the hypotheses B. identify hypothetical data C. set the criteria for a decision D. compute the test statistic

b

A researcher selects a sample of 121 participants from a population with a mean of 32 and a standard deviation of 22. What is the standard error of the mean? A. 32 B. 2.0 C. 0.5 D. There is not enough information to answer this question.

b

A researcher selects a sample of 36 students from a school population with a mean IQ of 100 and standard deviation of 12. She determines that the mean IQ in this sample is 104. Assuming she computes a one-sample z test at a .05 level of significance, what is the decision for a two-tailed test? A. Retain the null hypothesis; IQ scores in this sample are the same as those in the population. B. Reject the null hypothesis; IQ scores in this sample are significantly higher than those in the population. C. There is not enough information to make a decision.

b

As sample size increases, the standard error of the mean ______. A. increases B. decreases C. can increase or decrease D. does not change

b

A researcher determines that students study an average of 80 ± 20 (M ± SD) minutes per week. Assuming these data are normally distributed, what is the z score for students studying 60 min per week? A. 1.0 B. -1.0 C. 0.3413 D. 0.1587

b

A researcher obtains z = -6.45. What is the decision for a one-tailed test, upper-tail critical, at a .05 level of significance? A. to reject the null hypothesis B. to retain the null hypothesis C. It depends on the sample size. D. There is not enough information to make a decision.

b

Experimental research is typically conducted using a sampling strategy in which ______. A. the order of selecting participants matters B. the same participant can never be selected twice in the same sample C. participants are replaced after being sampled D. all of these

b

Suppose a researcher wants to make sure that the probability of committing a Type I error is less than 5%. How can the researcher control for this? A. set the value for a Type II error at .05 B. set the alpha level at .05 C. place the rejection region in both tails D. both B and C

b

The probability of committing a Type I error is stated by ______ and the probability for committing a Type II error is stated by ______. A. beta; alpha B. alpha; beta C. a p value; a p value D. the power; the power

b

1. The following distribution most closely approximates a ______. A. normal distribution B. positively skewed distribution C. negatively skewed distribution D. multimodal distribution

A. Normal Distribution

A researcher believes that increasing attention given to children will improve mean academic performance. Therefore, the alternative hypothesis should be ______. A. mean academic performance will increase B. mean academic performance will decrease C. mean academic performance will not change D. mean attention will increase

a

The mean of the sampling distribution of sample means is ______. A. equal to the population mean B. equal to the population variance C. both A and B D. none of these

a

The normal distribution is symmetrical, which means that ______. A. scores above the mean are distributed the same as scores below the mean B. extreme scores are possible in a normal distribution C. there are an infinite number of possible normal distributions D. this characteristic has no practical implication

a

Which of the following statements regarding the null hypothesis is true? A. The null hypothesis always makes statements about a population parameter. B. A decision in hypothesis testing is made about the alternative hypothesis, not the null hypothesis. C. The null hypothesis is the only hypothesis stated in hypothesis testing. D. all of these

a

Which type of sampling is most often applied by researchers in the behavioral sciences? A. theoretical sampling B. normal sampling C. experimental sampling D. standard normal sampling

c

The normal distribution has all of the following characteristics, except that ______. A. it is symmetrical B. its distribution is theoretical C. the total area under the curve is greater than 1.0 D. the mean, median, and mode are equal

c.