Ch9- Experimental Research

Question 1

random assigment

Answer 1

division of subjects into groups at the beginning of experimental research using a random process so the experimenter can treat the groups as equal

Question 2

science of the sophmore

Answer 2

first year psych grad students - generalizability limited

limited external validity of studies based on undergraduate samples usually using the experimental method.

Question 3

Matching

Answer 3

alternative to random assignment - infrequently used

relevant characteristics to match on - locate exact matches - hard to match on all characteristics - hard to known which are meaningful

Question 4

Parts of the experiment

Answer 4

1. independent var
2. dependent variable
3. pretest
4. post-test
5. experimental group
6. control group
7. random assignment

Question 5

pretest

Answer 5

measurement of the dependent variable prior to the introduction of treatment

Question 6

post test

Answer 6

is the measurement of the dependent variable after the treatment has been introduced into the experimental situation

Question 7

classical experimental design

Answer 7

has

• random assignment
• control group
• experimental group
• pretests and post-tests for each group

Question 8

pre-experimental designs

Answer 8

used when difficult to use classical
weaknesses that makes inferring a causal relationship more difficult

• lack random assignment
• weaker internal valdity

Question 9

one-shot case study design

Answer 9

only has experimental group, post-test and no pre-test

new staff training asking question after delivering food, record tips for all after a month

Question 10

one group pretest post-test design

Answer 10

One group, pretest, treatment, post test

no control or random assignment

hire, dont train take pretest, train take post test

Question 11

static group comparison

Answer 11

an experimental design with two groups, no random assignment and only a post test

train go to one of two resturants, retrain people at resturant one at 1m - experimental, control group retrained to not check in - tips recorded after

Question 12

quasi-experimental

Answer 12

experimental designs that are stronger than pre-experimental designs.

variations on the classical experimental design that an experimenter uses in special situations or when an experimenter has limited control over the independent variable

Question 13

two-group post test only design

Answer 13

identical to static except groups are randomly assignment

all parts of the classical design except a pretest

random assignment reduces the chance that the groups differed before the treatment but without a pretest researcher can not be certain that the groups began with respect to the independent variable

participation higher with reward example

Question 14

interrupted time series design

Answer 14

researcher uses one group and makes multiple pretest measures before and after the treatment.

• cigarette taxes jumped - taxes remained constant

dependent variable measured across many time points,treatment occurs in the midst often only once

Question 15

equivalent time series

Answer 15

an experimental design in which there are several repeated pretests, posttests, and treatments for one group, often over a period of time.

one-group design that extends over a time period,

Question 16

latin square designs

Answer 16

used to examine whether the order or sequence in which subjects receive multiple versions of the treatment has an effect

Question 17

Solomon four-group design

Answer 17

an experimental design in which subjects are randomly assigned to two control groups and two experimental groups. only one experimental group and one control group receive a pretest.

all four groups receive a post-test.

pretest can sometimes sensitize subjects to the treatment or improve their performance on the post-test - developed this to overcome that

Question 17

factorial design

Answer 17

two or more independent variables in combination

main effects and interaction effects - two or more variables that operate simultaneously

Question 17

Threats to internal validity

Answer 17

selection bias
history effects
maturation
testing effect
instrumentation
morality
statistical regression
diffusion of treatment
experimenter expectancy

Question 17

selection bias

Answer 17

threat to internal validity when groups in an experiment are not equivalent at the beginning of the experiment

subjects in experimental have a characteristic that affects the dependent variable

Question 17

maturation

Answer 17

long time periods

threat to internal validity - due to natural processes of growth, boredom, and so on that occur to subjects during the experiment and affect the dependent variable

Question 17

history effects

Answer 17

threats to internal validity that result from an occurrence that affects the dependent variable during an experiment but that is unplanned and outside the control of the experimenter

terrorist attack happens during racism study

Question 18

testing effect

Answer 18

a pretest measure that itself affects an experiment- threatens internal validity because more than the treatment alone affects the dependent variable

remembering items on a test

Question 18

instrumentation

Answer 18

a threat to reliability occuring when the dependent variable measure changes during an expeirment

scales for weight loss weaken

Question 19

morality

Answer 19

threat to internal validity due to subjects failing to participant through the entire experiment

attrition

Question 20

statistical regression

Answer 20

a problem of extreme values or a tendency for random errors to move group results toward the average - threat to internal validity

happens in two ways
1. subjects are unsusual with regard to dependent - started violent less violent later - begin at extremem move to average by chance

2. problem with measurement instrument - floor or ceiling scores - random chance will produce change btw pretest and post test

Question 21

diffusion of treatment

Answer 21

threat that research participants in different groups will communication with each other and learn about the others treatment - threat to internal validity

Question 22

experimenter expectancy

Answer 22

threat to internal validity not by a researcher’s purposefully unethical behaviour but by their indirectly communicating desired findings to the subjects

Question 23

reactivity

Answer 23

a threat to external validity that arises because subjects are aware they are in an experiment being studied

Question 24

hawthorne effect

Answer 24

a effect of reactivity named after a famous case in which subjects reacted to the fact that they were in an expeirment more than they reacted to the treatment.

participants responded not to the treatment but to the additional attention they received from being a part of the experiment - knowing they were being watched

Question 25

field experiment

Answer 25

experimental research that takes place in a natural setting

Question 26

natural experiment

Answer 26

quasi-experiment by which a researcher can examine the impact of a policy change or similar change in a social system by comparing an outcome of interest before and after such change is implemented.