Chapter 7: Causal Research Design: Experimentation

Test marketing

an application of a controlled experiment done in limited, but carefully selected, test markets. It involves a replication of the planned national marketing program for a product in the test markets.

Laboratory Environment

an artificial setting for experimentation in which the researcher constructs the desired conditions.

Interactive Testing Effect (IT)

an effect in which a prior measurement affects the test unit's response to the independent variable.

Main Testing Effect (MT)

an effect of testing occurring when a prior observation affects a latter observation.

Field Environment

an experimental location set in actual market conditions.

Maturation (MA)

an extraneous variable attributable to changes in the test units themselves that occur with the passage of time.

Selection Bias (SB)

an extraneous variable attributable to the improper assignment of test units to treatment conditions.

Mortality (MO)

an extraneous variable attributable to the loss of test units while the experiment is in progress.

Instrumentation (I)

an extraneous variable involving changes in the measuring instrument or in the observers or scores themselves.

Statistical Regression (SR)

an extraneous variable that occurs when test units with extreme scores move closer to the average score during the course of the experiment.

Experimental Design

the set of experimental procedures specifying (1) the test units and sampling procedures, (2) independent variables, (3) dependent variables, and (4) how to control the extraneous variables.

History (H)

Specific events that are external to the experiment but occur at the same time as the experiment.

Test Markets

a carefully selected part of the marketplace that is particularly suitable for test marketing.

Concomitant Variation

a condition for interring causality that requires that a cause, X, and an effect Y, occur together or vary together as predicted by the hypothesis under consideration.

External Validity

a determination of whether the cause-and-effect relationships found in the experiment can be generalized.

Internal Validity

a measure of accuracy of an experiment. It measures whether the manipulation of the independent variables, or treatments, actually caused the effects on the dependent variable(s).

One-group pretest-posttest design

a preexperimental design in which a group of test units is measured twice.

One-shot case study

a preexperimental design in which a single group of test units is exposed to a treatment X, and then a single measurement on the dependent variable is taken.

Static Group

a preexperimental design in which there are two groups: the experimental group (EG), which is exposed to the treatment, and the control group (CG). Measurements on both groups are made only after the treatment, and test units are not assigned at random.

Time Series Design

a quasi-experimental design that involves periodic measurements on the dependent variable for a group of test units. Then, the treatment is administered by the researcher or occurs naturally. After the treatment, periodic measurements are continued in order to determine the treatment effect.

Simulated Test Market

a quasi-test market in which respondents are preselected, then interviewed and observed on their purchases and attitudes toward the product.

Randomized Block Design

a statistical design in which the test units are blocked on the basis of an external variable to ensure that the various experimental and control groups are matched.

Latin square design

a statistical design that allows for the statistical control of two non-interacting external variables in addition to the manipulation of the independent variable.

Factorial Design

a statistical experimental design that is used to measure the effects of two or more independent variables at various levels and to allow for interactions between variables.

Standard Test Markets

a test market in which the product is sold through regular distribution channels. For example, no special considerations are given to products simply because they are being test-marketed.

Controlled Test Market

a test-marketing program conducted by an outside research company in field experimentation. The research company guarantees distribution of the product in retail outlets that represent a predetermined percentage of the market.

Multiple time series design

a time series design that includes another group of test units to serve as a control group.

Posttest-only control group design

a true experimental design in which the experimental group is exposed to the treatment but the control group is not and no pretest measure is taken.

Postttest-only Control Group Design

a true experimental design in which the experimental group is exposed to the treatment but the control group is not. Pretest an posttest measures are taken on both groups.

Pretest-posttest control group design

a true experimental design in which the experimental group is exposed to the treatment but the control group is not. Pretest and posttest measures are taken on both groups.

Solomon four-group design

a true experimental design that explicitly controls for interactive testing effects , in addition to controlling for all the other extraneous variables.

Debriefing

after the experiment, informing test subjects what the experiment was about and how the experimental manipulations were performed.

Demand Artifacts

the respondents attempt to guess the purpose of the experiment and respond accordingly.

Statistical Design

designs that allow for the statistical control and analysis of external variables.

Quasi-experimental Designs

designs that apply part of the procedures of true experimentation but lack full experimental control.

Pre-Experimental Designs

designs that do not control for extraneous factors by randomization.

True Experimental Designs

experimental designs distinguished by the fact that the researcher can randomly assign test units to experimental groups and also randomly assign treatments to experimental groups.

Test Units

individuals, organizations, or other entities whose response to independent variables or treatments is being studies.

Statistical Control

one method of controlling extraneous variables by measuring the extraneous variables and adjusting for their effects through statistical methods.

Matching

one method of controlling extraneous variables that involves matching test units on a set of key background variables before assigning them to the treatment conditions.

Randomization

one method of controlling extraneous variables that involves randomly assigning test units to experimental groups by using random numbers. Treatment conditions are also randomly assigned to experimental groups.

Design Control

one method of controlling extraneous variables that involves using specific experimental designs.

Confounding Variables

synonymous with extraneous variables, used to illustrate that extraneous variables can confound the results by influencing the dependent variable.

Experiment

the process of manipulating one or more independent variables and measuring their effect on one or more dependent variables, while controlling for the extraneous variables.

Independent Variables

variables that are manipulated by the researcher and whose effects are measured and compared .

Dependent Variables

variables that measure the effect of the independent variables on the test units.

Extraneous Variables

variables, other than the independent variables, that influence the response of the test units.

Causality

when the occurrence of X increases the probability of the occurrence of Y.