STATS quiz 7

When the standard deviation of the original population is small, the experiment tends to... 1. show a less significant difference between the two populations. 2. have a lower level of power. 3. have a higher level of power. 4. have a high level of Type II error.

have a higher level of power.

A child psychologist conducts a study to test whether infants born prematurely begin to walk earlier than do infants in general. Which of the following scenarios represents a Type II error? 1. The psychologist concludes that premature infants do walk earlier than infants in general when the true situation is that they actually do. 2. The psychologist concludes that premature infants do not walk earlier than infants in general when the true situation is that they actually do. 3. The psychologist concludes that premature infants do not walk earlier than infants in general when the true situation is that they actually do not. 4. The psychologist concludes that premature infants do walk earlier than infants in general when the true situation is that they actually do not.

The psychologist concludes that premature infants do not walk earlier than infants in general when the true situation is that they actually do.

If a study conducted at the .05 significance level has 80% power... 1. alpha = 95%, beta = 20%. 2. alpha = 5%, beta = 20%. 3. alpha = 95%, beta = 80%. 4. alpha = 5%, beta = 80%.

alpha = 5%, beta = 20%.

The decision to reject the null hypothesis using the z test is made... 1. if the z score is less than -1 or greater than 1. 2. by comparing the standard deviation of the sample (s) to the standard deviation of the population (σ). 3. by comparing the critical value of z to the test statistic, the actual z score of the sample. 4. if the z score is greater than 2.5.

by comparing the critical value of z to the test statistic, the actual z score of the sample.

If the critical value of z is -1.65 and the sample z score is 2.05, the correct decision is to... 1. fail to accept the research hypothesis. 2. fail to reject the null hypothesis. 3. reject the null hypothesis. 4. accept the research hypothesis.

fail to reject the null hypothesis.

Power is the probability that... 1. if the alternative hypothesis is false, the experiment will support the null hypothesis. 2. if the alternative hypothesis is true, the experiment will support it. 3. the alternative hypothesis will not be accepted incorrectly. 4. a Type I error will not be made.

if the alternative hypothesis is true, the experiment will support it.

A psychologist conducts a study and finds that d = -.63. This effect size would most likely be described as... 1. large. 2. an error because d cannot be negative. 3. small. 4. medium.

medium.

The effect size and the number of participants are two important determinants of... 1. power. 2. the minimum significant result. 3. alpha. 4. experimental significance.

power.

If the critical value of z is ±1.96 and the obtained value of z - the test statistic - is -2.05, the correct decision is to... 1. accept the alternative hypothesis. 2. reject the null hypothesis. 3. fail to reject the null hypothesis. 4. fail to accept the research hypothesis.

reject the null hypothesis

If a psychologist tests whether a new teaching method is more effective than the old one, the alternative hypothesis is that... 1. there is no difference in effectiveness of the old and new teaching methods. 2. there is a difference in effectiveness between the two methods, but no prediction is made. 3. the new teaching method is more effective than the old teaching method. 4. the old teaching method is more effective than the new teaching method.

the new teaching method is more effective than the old teaching method.

One important advantage of using effect sizes is that... 1. they directly indicate the statistical significance of the research hypothesis. 2. they indicate all the relevant parameters of a group of scores. 3. they are standardized scores that make comparisons of different studies easier. 4. they provide the same information as statistical significance, but they permit meta-studies.

they are standardized scores that make comparisons of different studies easier.

Type II errors concern psychologists because... 1. future research might be based on results mistakenly declared significant. 2. they could mean that experiments must be repeated to confirm positive results. 3. rejecting the null hypothesis should only occur when the research hypothesis is true. 4. they could mean that good theories or useful practical procedures are not used.

they could mean that good theories or useful practical procedures are not used.