Chapter 4

Question 1

variability due to chance

Answer 1

error variance, the fact that for any given pop. with standardized mean of 50, the true mean may vary some (for example, one group’s mean may be 49.7 and another group’s mean may be 52.3)

Question 2

sampling error

Answer 2

numerical value of a sample statistic probably will be slightly in error as a result of of the particular observations that happened to be included in the sample (like one unusually obnoxious child in a group of children)

Question 3

hypothesis testing

Answer 3

where data is ambiguous, attempting to determine if difference is small enough to dismiss as chance or large enough to entail significance

Question 4

sampling distribution of differences between means

Answer 4

distribution of differences between means of an infinite number of pairs of random samples drawn under certain specified conditions

Question 5

research hypothesis

Answer 5

idea researchers are hoping to prove, such as “Kids who eat more sugar behave more wildly.”

Question 6

null hypothesis

Answer 6

idea opposite to what researchers are hoping to prove, like “Kids who eat more sugar don’t behave more wildly.”
Fisher-We cannot prove that something is true, but we can prove something to be false. One can never claim to have “proved” the null hypothesis, but failure to reject the null hypothesis often means we have not collected enough data.

Question 7

alternative hypothesis

Answer 7

To prove the truth of a hypothesis, one would need an absolute value (which cannot be provided). For example, what is the absolute level one could assign to “wildness”? Instead, we must use the null hypothesis method for behavioral sciences.

Question 8

sample statistics

Answer 8

describe characteristics of samples

Question 9

test statistics

Answer 9

associated with specific statistical procedures and have their own sampling distributions

Question 10

decision-making

Answer 10

using arbitrary conventions to determine whether we should accept or reject our data

Question 11

rejection level

Answer 11

significance level-arbitrary number at which we choose to reject our findings (either less than or equal to .05 or .01)

Question 12

critical value

Answer 12

actual score that cuts off the highest 5%

Question 13

Type I error

Answer 13

erroneously rejecting the null hypothesis

Question 14

alpha

Answer 14

the probability of reaching a Type I error, erroneously rejecting a true null hypothesis

Question 15

Type II error

Answer 15

erroneously failing to reject the null hypothesis

Question 16

beta

Answer 16

the probability of reaching a Type I error, erroneously failing to reject the null hypothesis

Question 17

power

Answer 17

probability of correctly rejecting the null hypothesis when it is truly false, power=1-beta

Question 18

one-tailed test

Answer 18

directional test-the situation in which we reject the null hypothesis for only the lowest or only the highest mean differences; predicting that the individual will differ from the mean in only one direction of the mean (either above-positively or below-negatively the mean)

Question 19

two-tailed test

Answer 19

nondirectional test-the situation in which we reject the extremes at both the positive and the negative ends, used either in exploratory testing where the experimenter has no idea as to how outcomes will be affected or when an experimenter does have a good idea but wants to CYA, or when more than two groups are being tested and a one-tailed test wouldn’t work

Question 20

conditional probabilities

Answer 20

confusing the probability of the hypothesis given the data with the probability of the data given the hypothesis

Question 21

Tukey & Jones method

Answer 21

Instead of predicting an hypothesis (and a null hypothesis) before beginning, the experimenter simply gathers data and analyzes it before trying to draw conclusions. This is incredibly helpful because in most experiments, proving the null hypothesis perfectly is impossible and therefore moot.