Central Tendency
The most frequent score in the sample is the:
mode
The ____________ is the distance between the minimum and maximum scores.
range
When an experimenter states that the level of significance is the .05 level, he is setting the probability of committing which type of error?
Type I
The inferential statistic used to analyze differences between two separate groups is called the
independent-samples t-test
A simple count of how many times a score occurred in a sample is the:
a. percentage.
b. frequency.
c. cumulative percentage.
d. central tendency.
b. frequency.
Which measure of central tendency is the most sensitive to change?
Mean
Which of the following is NOT related to measuring variability?
a. Variance
b. Range
c. Mean
d. Standard deviation
c. Mean
Suppose the type of computer game (violent vs. scavenger hunt) really has an impact on players’ aggression but you do not reject the null hypothesis. You have made a...
Type II error
An independent samples t-test was used to assess differences in back pain scores between male and female soldiers.
Identify the dependent and independent variables.
back pain scores (DV), male (IV/condition 1), female (IV/condition 2)
______________ approximates the sample size (adjusts the sample slightly to make for a more accurate outcome).
Degrees of freedom
The appropriate measure of central tendency for a normally distributed interval variable is...
mean
The ____________ describes how much, in general, the scores in a sample differ from the mean.
standard deviation
Power is defined as:
a. Correctly rejecting a true null hypothesis
b. Correctly rejecting a false null hypothesis
c. Correctly retaining a true null hypothesis
d. Correctly rejecting a true alternative hypothesis
b. Correctly rejecting a false null hypothesis
The assumption that variances in populations are the same is called:
homogeneity of variance
a. variability we expect in a population whose variability equals the difference we found in our study.
b. span of differences expected in a population whose variability is equal to our sample standard deviations.
c. interval that includes the population mean difference represented by the mean difference in our study.
d. mean difference between our sample and the population means.
c. interval that includes the population mean difference represented by the mean difference in our study.
Which of the following shouldn’t you calculate for nominal variables?
a. Mean
b. Median
c. Standard deviation
d. All of the above
d. All of the above
A _________ distribution has its tail on the left.
negatively skewed
When a researcher claims that there is a difference between treatments (i.e., rejects the null hypothesis) when there really is no difference, what type of error is this?
Type I error
A researcher sought to find out which of two exercises was more effective in building endurance. One group used exercise A, and another group used exercise B. At the end of study, the researcher should compare the two groups' scores using a...
an independent t-test
a. 95% confident that the mean difference from the study represents a population of mean differences falling between 2.68 and 5.79.
b. 5% confident that the mean difference from the study represents a sample of mean differences falling between 2.68 and 5.79.
c. 95% confident that the mean difference from the study represents a population of mean differences falling outside of 2.68 and 5.79.
d. We can only be confident of the confidence interval if our means fall between 2.68 and 5.79.
a. 95% confident that the mean difference from the study represents a population of mean differences falling between 2.68 and 5.79.
Which of the following is the appropriate measure of central tendency to report with an extremely skewed distribution?
median
What percentage of scores in a normal distribution are between +1 and -1 standard deviation of the mean?
68%...remember the rule: 68-95-99.7
Increasing the sample size in a study from 30 to 50 increases the power of a study because
a. the larger sample size better represents the population and better represents any differences that exist in the population.
b. more people always create more differences.
c. larger groups allow the researcher to minimize mistakes in the procedure.
d. sample size is directly correlated to power.
a. the larger sample size better represents the population and better represents any differences that exist in the population.
An index of the strength of the relationship among variables (a measure of the magnitude of the difference between groups) is the definition of:
Effect size
a. 1.3%; medium
b. 3.5%; small
c. 13%; large
d. 13%: small
d. 13%: small