Chapter 9

Question 1

3 properties of a well designed experiment

Answer 1

1: vary at least one independent variable
2: ensure initial equivalence of participants
3: control al extraneous variables

Question 2

3 types of independent variables

Answer 2

environmental manipulations - manipulating aspects of the research setting
instructional manipulations - variation in instructions to participants
invasive manipulations - manipulating conditions in a participant’s body, ex stimulation, surgery, or drugs

Question 3

pilot test

Answer 3

initial test with some participants to ensure that the different levels of independent variable are different enough to be detected by participants
.are these two levels of lights different enough to be perceptible or significant?

Question 4

manipulation check

Answer 4

question during an experiment designed to determine whether the independent variable was manipulated successfully. like, did the participant notice the light was brighter in this condition compared to the participants in other conditions where the light was dimmer?

Question 5

subject/participant variables

Answer 5

things we cannot manipulate but vary, like the gender of a participant

Question 6

simple random assignment

Answer 6

every participant has an equal probability of being placed in any experimental condition

Question 7

matched random assignment

Answer 7

1. researcher obtains participant scores on a measure known to be relevant to outcome of experiment (typically a pretest measure of the dependent variable)
2. participants are ranked from highest to lowest
3. creates clusters based on the number of conditions in the experiment. for ex, 2 highest scoring would be split into condition a and condition b. next 2 highest scoring would be split as well. all the way to bottom scoring

Question 8

randomized groups design

Answer 8

simple random assignment or matched random assignment

Question 9

between-groups design

Answer 9

interested in behavior BETWEEN groups of participants

as in participants in condition a versus those in condition b

Question 10

within-subjects design

Answer 10

.each participant experiences all conditions or all levels of independent variable
.don’t have to worry about randomizing, because no differences between conditions b/c all conditions experienced by each participant
.has more power!
.subject to order and carry over effects tho

Question 11

order effects

Answer 11

behavior affected by the order in which they participate in the various conditions of the experiment
.three types: practice, fatigue, sensitization.

Question 12

practice effects

Answer 12

performance improves because complete the dependent variable several times
.like if you do a simple memory test, they’re going to improve at it each subsequent time!

Question 13

fatigue effects

Answer 13

participants become bored, tired, or less motivated as experiment progresses
.may perform least well on experimental condition they receive last

Question 14

sensitization

Answer 14

after completing dependent variable several times, participants may begin to realize what the hypothesis of experiment is, then start to respond differently!
.aka they become sensitized to the purpose of the experiment

Question 15

counterbalancing

Answer 15

guards against order effects

.present levels of independent variable in different orders to different participants

Question 16

latin square design

Answer 16

.method of counterbalancing
.each condition appears once at each ordinal position (1st, 2nd, 3rd, etc.) and each condition precedes and follows every other condition once (SEE PAGE 193!!)

Question 17

carryover effects

Answer 17

effect of a particular treatment condition persists even after the condition ends
.one level of IV is still present when the next level is introduced

Question 18

treatment variance

Answer 18

.aka PRIMARY VARIANCE

.portion of variance in participants’ scores that is due to the independent variable

Question 19

confound variance

Answer 19

.aka SECONDARY VARIANCE
.portion of variance in participants’ scores that is due to extraneous variables that differ systematically between the experimental groups.
.MUST BE ELIMINATED AT ALL COSTS

Question 20

systematic variance

Answer 20

.aka BETWEEN-GROUPS VARIANCE
.part of total variance that reflects differences among the experimental groups
.composed of both treatment variance and confound variance

Question 21

error variance

Answer 21

.aka WITHIN-GROUPS VARIANCE
.result of unsystematic differences among participants
.participants differ when enter experiment in terms of ability, personality, etc.
.experimenter will treat participants in slightly diff ways…
.measurement error…
.want to REDUCE but can’t really eliminate

Question 22

internal validity

Answer 22

degree to which a researcher draws accurate conclusions about the effects of the independent variable
.experiment internally valid when it eliminates all potential sources of confound variance

Question 23

counfounding

Answer 23

something other than the independent variable differs in some systematic way
.a fatal flaw!

Question 24

biased assignment

Answer 24

.aka selection threat

.effects are due to nonequivalent groups rather than independent variable

Question 25

differential attrition

Answer 25

loss of participants during a study that is different under each condition because of the nature of each condition
.e.g. one condition might be more stressful than the other, leading the ones that finish that condition to be different (more hardy) than the other condition which made less people drop out

Question 26

pretest sensitization

Answer 26

taking a pretest may lead participants to react differently than they would have if they had not been pretested.
.give a pretest, then same test after experiment… are participants just getting better scores because they’re doing the same test a second time, or have they actually changed because of the IV?

Question 27

history effects

Answer 27

one’s past experiences or history causes them to react differently to IV than other participants… like if everyone had to watch a rape video in one condition… and a couple of the people had experienced rape, it would dramatically skew the results

Question 28

demand characteristics

Answer 28

.participants act in a way that they think the experimenters want them to act
.think if they had to go to the bathroom while being watched… no doubt EVERYONE would ALWAYS wash their hands

Question 29

threats to internal validity, GO

Answer 29

.Biased assignment
.Differential Attrition
.Pretest Sensitization
.History effects
.Misc confounds

Question 30

Sources of error variance

Answer 30

.individual differences
.transient states
.environmental factors
.differential treatment
.measurement error
(make sure understand, on page 204 if need)

Question 31

Experimenter’s dilemma

Answer 31

more tightly experimenter controls the setting, the more internally valid the results but lower the external validity
.but it’s ok because we don’t always prioritize external validity, not always wanting to generalize to whole population or something
.however if results aren’t internally valid, they can’t ever be generalized or externally valid
.so internal validity is more important

Question 32

pros cons of web-based research

Answer 32

PROS
.large sample sizes
.diverse sample sizes
.easy to get specific samples with specific characteristics
.less susceptible to social desirability effects and experimenter expectancies… etc.
CONS
.no way of confirming one’s identity or what they say, could take it many times
.can’t control setting where people take test
.people often get bored halfway through and don’t complete