Chapter 14

Question 1

randomized experiment

Answer 1

Assigning a group randomly to the control or experimental group

Question 2

placebo

Answer 2

Control group receives
Inert or ineffective treatment

Question 3

experimental subject/unit

Answer 3

Units randomized to control or experimental group

Question 4

random assignment

Answer 4

Used to provide or withhold an intervention or treatment following a procedure to flipping a coin
Researcher must randomize assignment of the IV
Participants randomly assigned to treatment and control groups
Helps ensure all groups are identical on all z variables
Have random assignment but not random sample

Question 5

statistical equivalence

Answer 5

Balances the treatment and control groups in terms of both measured and unmeasured variables with bounds of chance as differences
Experiments are the “gold standard” for getting close to causality
Note: we still can’t observe causation here. The book does a bad job of explaining this
But, out of all the research designs we have, it the design that generally gives us the most confidence in arguing for cause and effect

Question 6

haphazard randomization

Answer 6

Less formal procedure that mimics true random assignment

Question 7

why random assignment?

Answer 7

Statistical equivalence on all variables

Question 8

randomized experiment

Answer 8

Seeks to isolate the causal relationship between one explanatory variable, the treatment (x) and one or more response variables or outcomes (y)
Treatment → outcome or x → y

Question 9

exogenous

Answer 9

X, the treatment is known to independent from and uncorrelated with all the other variables causing y

Question 10

experiments have what kind of internal and external validity

Answer 10

high internal low external

Question 11

internal validity

Answer 11

Confidence that the effect of X on Y is real

Question 12

external validity

Answer 12

Confidence that relationship between X and Y generalized beyond experiment

Question 13

threats to internal validity

Answer 13

Internal - differences between participants in treatment and control groups (other than X)

Question 14

selection

Answer 14

Individuals selected into treatment are different from those in control

Question 15

experiment mortality

Answer 15

Ppl. turning out and not receiving treatment
Only threat if creates difference between treatment and control group so if don’t mess up random assignment should be no threat

Question 16

threats to external validity

Answer 16

any differences between participants in study v. non participants and setting of lab v. real world

Question 17

unrepresentative population

Answer 17

doesn’t represent real world

Question 18

realism

Answer 18

setting we are in for experiment does not look anything like real world where might get this treatment

Question 19

mundane realism

Answer 19

events look way they do in real world

Question 20

experimental realism

Answer 20

subjects don’t take the experiment seriously

Question 21

psychological realism

Answer 21

the events triggered the same thoughts and emotions and processes as real-world events

Question 22

Hawthorne effect

Answer 22

subjects behave differently when they know they are being watched or monitored

Question 23

lab experiments

Answer 23

Take place in lab or specialized location
Intervening to create exogenous change in one variable while holding other variables constant

Question 24

field experiments

Answer 24

Takes place in real world setting not in artificial lab or simulation like school sor businesses → substantial time, organization

Question 25

survey experiments

Answer 25

Method of incorporating an experiment in the design and structure of the survey instrument itself Often used to test effects of variation in questionnaire or wording also referred to as split-ballot survey

Question 26

split-ballot survey

Answer 26

print off copies of survey A and survey B and randomly assign

Question 27

cluster randmoizibiliity

Answer 27

Groups or clusters rather than individuals are randomized Helps prevent leakage of the treatment to the control group Less statistical equivalence from randomization

Question 28

arms experiment

Answer 28

Various possible treatments Basic experiment has two arms - treatment and control Randomized study can compare multiple possible treatment or control conditions

Question 29

does-response relationship

Answer 29

How the effect of the experiment varies as dosage increases Ex. large class size v. small, but how large?

Question 30

linear trend

Answer 30

large the does larger the response

Question 31

curvilinear trend

Answer 31

as when an increasing dose reaches a point of diminishing response

Question 32

abrupt trend

Answer 32

effect kicks in all at once only when the dosage reaches a particular level

Question 33

analysis of randomized experiments

Answer 33

Usually just a difference of means

Question 34

sample size

Answer 34

Number of units in each group Each group must be large enough to achieve balance and to get desired precision of treatment effect Can use power analysis to determine sample sizes

Question 35

drawbacks of randomized experiments

Answer 35

Not all IV’s are controllable Ethical considerations prevent some experiments Low external validity Can resolve some of these problems with natural and quasi experiments

Question 36

factorial experiments

Answer 36

Experiments that try to measure the effects of more than one independent variable called factors

Question 37

main effects

Answer 37

Average of one factor across levels of the other factors in experiment

Question 38

interaction effects

Answer 38

Effect of both factors together is more or less than the sum of the two main effects

Question 39

between subjects experiments

Answer 39

When a group could end up i either one group or the other but not both Comparison is between subjects or units in treatment or control group

Question 40

within-subjects experiments

Answer 40

Experiment applies to two or more treatments to same people at different times Experimental conditions are within each person or unit so they each are exposed to both treatment and control conditions

Question 41

repeated - measures experiments

Answer 41

Repeated outcomes measures taken on each sub experimental and simply observe people repeatedly over time

Question 42

unobtrusive measures

Answer 42

Measures that occur naturally or routinely or otherwise do not disturb the subjects in an experiment

Question 43

blind experiments

Answer 43

Help correct the problem of the placebo effect by keeping subjects ignorant of which group they are in

Question 44

double-blind experiments

Answer 44

Researcher and participant don't know what groups are which

Question 45

contamination

Answer 45

When something happens in the course of implementing the study that compromises the integrity and logic of the experiment

Question 46

noncompliance

Answer 46

Treatment group fails to fully follow the treatment

Question 47

attrition

Answer 47

Participants dropping out from experiment

Question 48

minimal detectable effect

Answer 48

Smallest effect that would still have practical significance

Question 49

heterogenous treatment effect

Answer 49

Different people respond differently to treatment

Question 50

average treatment effects

Answer 50

Suggest the average of the various individual effects that the treatment ha on each person who participates in study