Chapter 11 - Experimental Designs Flashcards

1
Q

Establishing a Causal Relation

A
  • Association
    – Independent and dependent variables covary
  • Temporal precedence
    – Presumed cause (IV) precedes presumed effect (DV)
  • Isolation
    – Presumed cause (IV) must be able to affect the presumed effect
    (DV) all by itself (NOT due to another factor – i.e., a nuisance,
    confounding, contaminating, or extraneous variable)
    – Does NOT mean that there is only one cause for any given effect
    (DV) – think “a” cause, not “the” cause
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2
Q

Extent of Researcher Interference

A

Control

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3
Q

Extent of Researcher Interference

A

Control

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4
Q

Control is ____

A

– Important for establishing causality
– Designs vary in degree & forms of control

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5
Q

Factors of cause-probing Experiment

A

– Manipulation of IV(s)
– Random assignment of units to conditions
* Control & experimental
– Measure effects on DV(s)
– Control potential
confounds
– Clarification:
* Sometimes researchers will do a pre-test and post-test on the DV
* Pre-testing not a defining feature of an experiment

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6
Q

Factors of cause-probing Quasi-experiment

A

– Very similar to experiment
– Except: No random assignment
* May use intact or selfselected groups instead
– More likely to measure potential confounds
* Statistical control
– Similar to both experimental & relational designs

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7
Q

What was the Hypothesis of the Popcorn Experiment video?

A

Orville popcorn makes movies more enjoyable.

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8
Q

List the below Features of the Popcorn experiment video

– Manipulation (IV/treatment/intervention)?
– DV/outcome?
– Assignment to conditions?
– Other considerations (e.g., nuisance variables)?

A

– Manipulation (IV/treatment/intervention)?
——The Popcorn
– DV/outcome?
—— Perceived enjoyment (Rated by patrons)
– Assignment to conditions?
—— Quasi-Experiment
– Other considerations (e.g., nuisance variables)?
—— Lifting of the curtain, Temperature variance,

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9
Q

Internal Validity

A

The extent to which causal inferences (e.g., A causes B) are justified by a research design.

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10
Q

External Validity

A

The extent to which the results from a study (e.g.,
a causal relation between A and B) can be applied
to other settings, people, or events.

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11
Q

Threats to Validity

A

History
Maturation
Testing
Selection bias
Mortality (attrition)
Statistical regression (Regression to the mean)
Instrumentation
General observation

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12
Q

Threats to Validity with History

A

Events occurring concurrently with the treatment could cause the observed effect on the DV.

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13
Q

Threats to Validity with Maturation

A

Naturally occurring changes over time could
be confused with a treatment effect.

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14
Q

Threats to Validity with Testing

A

Exposure to a test can affect score on subsequent
exposures to that test, and this could be confused
with a treatment effect.
* Main (pre-test affects post-test)
* Interactive (pre-test affects reaction to the treatment)

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15
Q

Threats to Validity with Selection bias

A

Systematic differences between conditions in
respondent characteristics that could cause any
observed effect.

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16
Q

Threats to Validity with Mortality (attrition)

A

Loss of respondents to treatment or to
measurement can produce spurious effects if the
attrition is systematically correlated with
conditions (members of one group are more likely
to drop out).

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17
Q

Threats to Validity with Statistical regression

A

When units are selected for their extreme scores,
they will often have less extreme scores on
repeated measurements or on other variables.

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18
Q

Threats to Validity with Instrumentation

A

The nature of a measure may change over time or
conditions in a way that could be confused with a
treatment effect.

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19
Q

Threats to Validity with General observation

A

“Factors Affecting the Validity of Experiments” or “Threats to Validity”
* Inclusion of this material is a nice feature of an introductory
research methods text!
* More complete lists of threats to validity are available
elsewhere.

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20
Q

Experimental Designs

A

Basic

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21
Q

Experimental Designs

A

Pretest-posttest

22
Q

Experimental Designs

A

Switching replications

23
Q

Experimental Designs

A

Longitudinal

24
Q

Control group considerations

A

“No treatment” control is not a defining feature
* E.g., New teaching method vs. no teaching at all???
* Use placebos as a last resort (World Medical Association).
– Instead use new vs. standard treatment (both carefully defined)

25
Q

In quasi-experiments, sometimes “___________” is used instead of “control group”

A

comparison group

26
Q

Lab experiment

A

An experimental design set up in an artificially contrived setting where controls and manipulations are introduced to establish cause‐and‐effect relationships among variables of interest to the researcher.

27
Q

Field experiment

A

An experiment done to detect cause‐and‐effect relationships in the natural environment in which events normally occur.

28
Q

Manipulation

A

How the researcher exposes the subjects to the independent
variable to determine cause‐and‐effect relationships in experimental designs.

29
Q

Control group

A

The group that is not exposed to any treatment in an experiment.

30
Q

Treatment

A

The manipulation of the independent variable in experimental designs so as to determine its effects on a dependent variable of interest to the researcher

31
Q

Match groups

A

A method of controlling known contaminating factors in
experimental studies, by deliberately spreading them equally
across the experimental and control groups, so as not to confound the cause‐and‐effect relationship.

32
Q

Randomization

A

The process of controlling the nuisance variables by randomly assigning members among the various experimental and control groups, so that the confounding variables are randomly distributed across all groups.

33
Q

Internal validity of experiments

A

Attests to the confidence that can be placed in the cause‐and‐
effect relationship found in experimental designs.

34
Q

Field experiment

A

An experiment done to detect cause‐and‐effect relationships in the natural environment in which events normally occur.

35
Q

External validity

A

The extent of generalizability of the results of a causal study to other field settings.

36
Q

History effects

A

A threat to the internal validity of the experimental results, when events unexpectedly occur while the experiment is in progress and contaminate the cause‐and‐effect relationship.

37
Q

Maturation effects

A

A threat to internal validity that is a function of the biological,
psychological, and other processes taking place in the
respondents as a result of the passage of time.

38
Q

Pretest

A

A test given to subjects to measure the dependent variable before exposing them to a treatment

39
Q

Posttest

A

A test given to the subjects to measure the dependent variable after exposing them to a treatment.

40
Q

Testing effects

A

The distorting effects on the experimental results (the posttest scores) caused by the prior sensitization of the respondents to the instrument through the pretest.

41
Q

Mortality

A

The loss of research subjects during the course of the experiment, which confounds the cause‐and‐effect relationship.

42
Q

Statistical regression

A

The threat to internal validity that results when various groups in the study have been selected on the basis of their extreme (very high or very low) scores on some important variables

43
Q

Instrumentation effects

A

The threat to internal validity in experimental designs caused by changes in the measuring instrument between the pretest and the posttest.

44
Q

Selection effects

A

The threat to internal validity that is a function of improper or
unmatched selection of subjects for the experimental and control groups.

45
Q

Experimental design

A

A study design in which the researcher might create an artificial setting, control some variables, and manipulate the independent variable to establish cause‐and‐effect relationships.

46
Q

Experimental group

A

The group exposed to a treatment in an experimental design.

47
Q

Nuisance variable

A

A variable that contaminates the cause‐and‐effect relationship.

48
Q

Ex post facto experimental design

A

Studying subjects who have already been exposed to a stimulus and comparing them to those not so exposed, so as to establish cause‐and‐effect relationships (in contrast to establishing cause‐ and‐effect relationships by manipulating an independent variable in a lab or a field setting).

49
Q

Solomon four‐group design

A

The experimental design that sets up two experimental groups and two control groups, subjecting one experimental group and one control group to both the pretest and the posttest, and the other experimental group and control group to only the posttest.

50
Q

Double‐blind study

A

A study where neither the experimenter nor the subjects are
aware as to who is given the real treatment and who the placebo.

51
Q

Simulation

A

A model‐building technique for assessing the possible effects of changes that might be introduced in a system

52
Q
A