Chapter 10: Introduction to simple experiments

Question 1

comparison group

Answer 1

a group in an experiment whose levels on the independent variable differ from those of the treatment group in some intended and meaningful way

Question 2

control group

Answer 2

a level of the independent variable that is intended to represent “no treatment” or a neutral condition

Question 3

placebo group

Answer 3

when the control group is exposed to an inert treatment

Question 4

design confound

Answer 4

a threat to the internal validity of an experiment in which a second variable happens to vary systematicaly along with the independent variable and is therefore an alternative explanation for the results

Question 5

systematic variability

Answer 5

consistently reflects independent variables and their influences, often analyzing control and an experimental group, or groups

Question 6

unsystematic variability

Answer 6

variability within individuals and/or groups of individuals

Question 7

selection effects

Answer 7

occur when the kinds of participants at one level of the independent variable are systematically different from those at the other level

Question 8

matched groups

Answer 8

an experimental design technique in which participants who are similar on some measured variable are grouped into sets, and then randomly assigned to the different experimental conditions

Question 9

independent-groups design

Answer 9

different groups of participants are exposed to different levels of the independent variable, such that each participant experiences only one level of the independent variable

Question 10

within-groups design

Answer 10

each participant is presented with all levels of the independent variable

Question 11

posttest-only design

Answer 11

an experiment using the independent-groups design in which participants are tested on the dependent variable once, after the experimental manipulation

Question 12

pretest/posttest design

Answer 12

an experiment using an independent-groups design in which participants are tested on the key dependent variable twice, once before and once after exposure to the independent variable

Question 13

repeated measures design

Answer 13

an experiment using a within-group design in which participants respond to a dependent variable more than once, after exposure to each level of the independent variable

Question 14

concurrent measures design

Answer 14

an experiment using a within-groups design in which participants are exposed to all levels of the independent variable at roughly the same time, and a single attitudinal or behavioral presence is the dependent variable

Question 15

order effects

Answer 15

exposure to one condition changes participant responses to a later condition

Question 16

practice effects

Answer 16

participants’ performance improves over time because they become practiced at the dependent measure and not because of the manipulation or treatment

Question 17

carryover effects

Answer 17

some form of contamination carries over from one condition to the next

Question 18

counterbalancing

Answer 18

a method in a repeated-measures experiment in which levels of the independent variable are presented in different sequences to control for order effects

Question 19

latin square

Answer 19

a system that ensures that every condition in a within-groups design appears in each position at least once

Question 20

demand characteristics

Answer 20

a cue that leads participants to guess a study’s hypothesis or goals and is therefore a threat to internal validity because they create alternative explanations for the results

Question 21

manipulation checks

Answer 21

an extra dependent variable that can be included to determine how well a manipulation worked

Question 22

pilot study

Answer 22

a study completed before the study of primary interest, usually to test the effectiveness or characteristics of the manipulation

Question 23

treatment group

Answer 23

containts the participants in an experiment who are exposed to the level of the independent variable that involves medication, therapy, or placebo