Chapter 11

Question 1

alternative explanation

Answer 1

the existence of any systematic difference between groups other than the experimental variables that threaten internal validity

Question 2

experimental variables

Answer 2

properties an experimenter can manipulate or expose people to

Question 3

independent variable

Answer 3

the variable we believe to have a causal influence on our outcome variables

Question 4

counterbalancing

Answer 4

varying the order of experimental conditions across participants in a repeated measures design // helps to assure internal validity + controls for possible contamination

Question 5

failure of randomization

Answer 5

for any given study, it is possible that particular kinds of participants will not be evenly distributed across experimental conditions

Question 6

random assignment

Answer 6

a way of assigning participants to the levels of the independent variable so that the groups do not differ as the study begins

Question 7

randomized experiment

Answer 7

a research design in which individuals are randomly assigned to various levels of the independent variable

Question 8

repeated measures design

Answer 8

rather than some participants being in one condition and some in the other, all participants are in both conditions

Question 9

artifacts

Answer 9

an unintended effect on the dependent variable that is caused by some feature of the experimental setting other than the independent variable

Question 10

construct validity

Answer 10

making sure that our variables capture the construct we wish to measure

Question 11

differential mortality

Answer 11

when mortality rates are different for the various experimental groups // posing threat to internal validity

Question 12

factorial design

Answer 12

design containing every possible combination of two or more independent variables

Question 13

history

Answer 13

any event that is unrelated to the independent variable and yet could affect the dependent variable

Question 14

instrumentation

Answer 14

any change that occurs over time in measurement procedures or devices

Question 15

interaction effect

Answer 15

when the effect of one variable differs depending on the level of the other variable

Question 16

main effect

Answer 16

the effect of one independent variable, ignoring the others

Question 17

manipulated variable

Answer 17

when researchers create rather than measure levels of an independent variable

Question 18

manipulation check

Answer 18

a measure of the independent variable construct after they have measured it

Question 19

maturation

Answer 19

any naturally occurring process within persons that could cause a change in their behavior (i.e. fatigue, boredom, growth)

Question 20

mortality

Answer 20

any attrition (gradual loss) of participants from a study

Question 21

pretests

Answer 21

an additional set of tests or observations of the dependent variable before the experimental treatment

Question 22

selection

Answer 22

any pre-existing differences between individuals in the different experimental conditions that can influence the dependent variable

Question 23

selection by maturation

Answer 23

when there are differences between individuals in the treatment groups that produce changes in the groups at different rates