Chapter 8

Question 1

Point estimate

Answer 1

a summary statistic from a sample that is just one number used as an estimate of the population parameter; rarely exactly accurate

Question 2

Interval estimate

Answer 2

based on a sample statistic and provides a range of plausible values for the population parameter; usually constructed by adding and subtracting a margin of error from a point estimate

Question 3

Confidence interval

Answer 3

an interval estimate based on a sample statistic, which includes the population mean a certain percentage of the time if the same population is sampled from repeatedly

Question 4

What happens to the test statistic as the sample size increases?

Answer 4

it also increases, which may explain why a small difference is statistically significant with a large sample but not with a small sample

Question 5

Effect size

Answer 5

indicates the size of a difference and is unaffected by sample size; tells us how much 2 populations do not overlap

Question 6

2 ways to decrease the amount of overlap between distributions

Answer 6

(1) means are farther apart (2) variability within each distribution of scores is smaller

Question 7

Cohen’s d

Answer 7

standardized difference between means; a measure of effect size that expresses the difference between 2 means in terms of standard deviation

Question 8

Meta-analysis

Answer 8

a study that involves the calculation of a mean effect size from the individual effect sizes of more than one study; provides added statistical power

Question 9

Forest plot

Answer 9

shows the confidence interval for the effect size of every study

Question 10

Statistical power

Answer 10

a measure of the likelihood that we will reject the null hypothesis, given that it is false (making the correct decision) or the probability that we will not make a type II error

Question 11

Formula for power

Answer 11

effect size x sample size