Lester Chapter 12

Front 1

Purpose of Experimental Research

Back 1

to control relationships among a set of variables in order to enable evaluation of causal relationships between specific variables of interest to the study.

Front 2

Basic Issues of Experimental

Back 2

In designing an experiment, decisions have to be made with respect to the four basic issues; Independent variable(s) to be manipulated, Dependent variable(s) to selected and measured, Extraneous variables to be controlled and Assignment of test units to the experimental treatments

Front 3

Manipulation of the Independent Variable

Back 3

Experimental Treatment, Experimental Group, several experimental treatment levels, several independent variables, and control group

Front 4

Selection and measurement of the dependent variables

Back 4

based on the purpose of the research, measurement and latency

Front 5

Test Units

Back 5

persons or entities whose responses are to be measured—individuals, teams, departments, school systems, supermarkets, airports, etc.

Front 6

Sample Selection Error

Back 6

bias introduced by inappropriate selection of test units—MWC business students may not be representative of total student population

Front 7

Random Sampling Error

Back 7

statistical fluctuation resulting from chance in selecting test units for the sample—unavoidable

Front 8

Randomization

Back 8

the assignment of subjects to treatments on the basis of chance. Generally considered the best procedure for controlling extraneous variables. Scatters or evens out the potential effects of extraneous variables

Front 9

Matching

Back 9

assigning test units to experimental treatments so groups are matched for extraneous variables that might distort results such as age, gender, education, income, etc.

Front 10

Repeated Measures

Back 10

subjecting the same subjects to all experimental treatments. Eliminates error due to subject differences but may introduce other problems such as “practice” or “history” effects.

Front 11

Constant error

Back 11

term usually used for “systematic error” when discussing experiments—error attributable to flaw in design or execution of the experiment.

Front 12

Extraneous variables

Back 12

variables that, uncontrolled, distort results in a particular direction every time an experiment is repeated and which mask the true state of affairs
o Example – consistently administering one experimental treatment in the morning and the other one in the afternoon

Front 13

Demand characteristics

Back 13

experimental procedures that hint to subjects the nature of the hypothesis and suggest—“demand”—that they respond in a particular way.
o Experimenter bias – a constant error caused by the experimenter’s presence, actions, or attitudes—appearing eager, authoritarian, etc.
o Guinea pig effect – a constant error caused by subjects behaving abnormally in order to “cooperate” with or “please” the experimenter.
o Hawthorne effect – a constant error caused by subjects’ knowing they are participating in “research”—a kind of status/motivational effect

Front 14

Constancy of conditions

Back 14

when extraneous variables can’t be eliminated, subjects in various treatments are exposed to identical conditions except for the treatment itself—assumes the effects of extraneous factors are spread evenly across all treatment conditions

Front 15

Order of presentation bias

Back 15

error caused by subjects’ accumulating experience or savvy in the course of responding to multiple experimental treatments.

Front 16

Counterbalancing

Back 16

technique to reduce error caused by order of presentation—varying the order of experimental treatments for different experimental groups

Front 17

Blinding

Back 17

technique to control subjects’ knowledge of whether or not they have been given a particular experimental treatment.

Front 18

Double-blind design

Back 18

neither the subjects nor the experimenter know which are the experimental and which are the control conditions.

Front 19

Random assignment

Back 19

if extraneous factors can’t be controlled, it is assumed that their effects will be equally present in all experimental conditions through random assignment.

Front 20

Debriefing

Back 20

giving subjects all pertinent facts about the nature and purpose of the experiment after its completion.

Front 21

Basic Design

Back 21

a single independent variable is manipulated to observe its effect on single dependent variable

Front 22

Factorial Designs

Back 22

two or more independent variables are manipulated simultaneously to measure both main effects and the effect of their interaction on a dependent variable

Front 23

Laboratory Experiment

Back 23

an experiment conducted in an artificial setting in which the experimenter has almost complete control mover the research setting

Front 24

Tachistoscope

Back 24

a device that controls the amount of time a subject is exposed to a visual image.

Front 25

Field Experiment

Back 25

an experiment conducted in a natural setting—often for a long period of time—in which the experimenter has less control over extraneous variables.

Front 26

Internal Validity

Back 26

whether an experimental treatment was the sole cause of change in a dependent variable. Six common extraneous variables raise issues of internal validity ; Maturation Effect, instrumentaion effect, selection effect, testing effect, history effect, mortality effect

Front 27

Maturation Effect

Back 27

caused by changes in the experimental subjects over time such as boredom, aging, attitude.

Front 28

Instrumentation Effect

Back 28

a change in the wording of a questionnaire, a change in interviewers, or a change in procedures used to measure the dependent variable

Front 29

Selection Effect

Back 29

sample bias resulting in differential selection of subjects for the various experimental treatments—such as age, gender, or educational level.

Front 30

Testing Effect

Back 30

in a before- and after-study, an effect of pretesting that sensitizes subjects when tested for the second time

Front 31

History Effect

Back 31

a specific event in the external environment occurring between the first and second measurements of the experiment—beyond control of the experimenter—that affects the validity of the experiment

Front 32

Mortality Effect

Back 32

sample attrition that occurs when some subjects withdraw from an experiment before it is completed

Front 33

External Validity

Back 33

the ability to generalize the results of an experiment to similar conditions outside the experiment itself—transferring the results to the real world

Front 34

The Trade-off

Back 34

the choice between a laboratory experiment and a field study always involves a trade-off. A field study may achieve higher external validity at the expense of internal validity—meaning the results may be specific to the real-world field situation only. Likewise, the results of a laboratory experiment may not be generalizable to the real world.

Front 35

One Shot Design

Back 35

Flawed quasi experiment because it has no comparison group and no control over extraneous variables (exp. offering a prize to boost sales)

Front 36

One-Group Pretest-Posttest Design

Back 36

Flawed quasi experiment. SOUrces of error include maturation effect, history effect, mortality effect, instrumentation effect

Front 37

Static Group Design

Back 37

Flawed Quasi experiment. • Major weakness is that there may be systematic differences in the groups selected, e.g., volunteers used for the experimental treatment

Front 38

Pretest-Posttest Control Group Design

Back 38

It is assumed that the effects any extraneous variables are balanced by the randomization, but a testing effect is still possible if subjects are sensitized by the test questions to the purpose of the research

Front 39

Posttest Only Control Group Design

Back 39

Used when: (1) pretest not possible, or (2) groups are known to be equal. Eliminates testing effect and assumes extraneous variables operate equally on both groups.

Front 40

Solomon Four-Group Design

Back 40

Separates out maturation effect, testing effect, and treatment effect and is rarely used in business because of effort, time, and cost

Front 41

Compromise Experimental Design

Back 41

sometimes random assignment is not possible, e.g., when administering treatment to departments within an organization. In such cases compromise designs are unavoidable, e.g., assigning units as a whole to experimental treatments.

Front 42

Time Series Design

Back 42

repeated observations are taken over an extended period of time—e.g., as in political polls—enables researcher to evaluate: The immediate effect of an event or experimental treatment
The permanence of the effect. Time series designs are subject to, History effect and Loss of control (therefore are quasi-experimental designs)

Front 43

Completely Randomized Design

Back 43

randomly assigns experimental units to treatments to investigate the effects of a single independent variable

Front 44

Randomized Block Design

Back 44

an extension of the completely randomized design in which each experimental treatment is administered to each value (block) of a particular extraneous variable.

Front 45

Factorial Design

Back 45

allow for testing the effects of two or more treatments (factors) at various levels

Front 46

Latin Square Design

Back 46

attempts to control or block out the effect of two or more confounding extraneous factors. The major assumption—and drawback—of the Latin Square design is that interaction effects are expected to be minimal or nonexistent. A Latin Square design can have any number of treatments