Research method in which conditions are controlled so that 1 or more independent variables can be manipulated to test a hypothesis about a dependent variable.
Allows evaluation of causal relationships while all other variables are controlled.
Steps in Experimental Research – 1) Decide on Field or Laboratory Experimental Design
Laboratory Experiment: conducted in a lab or an artificial setting to obtain almost complete control over the research setting.
Field Experiment: conduced in a natural setting, where complete control of extraneous variables is not possible. Generally used to finetune strategies and determine sales volume.
Laboratory Experiment – Tachistoscope
A device that controls the amount of time a subject is exposed to a visual image.
Controlled Store Test
Hybrid between a laboratory experiment and a test market whereby test products are sold in a small number of selected stores to actual customers.
Decisions about Elements of an Experiment
– Manipulation of the Independent Variable.
– Selection and Measurement of the Dependent Variable.
– Selection and Assignment of Subjects.
– Control over Extraneous Variables.
Steps in Experimental Research – 2) Decide on the Choice of Independent and Dependent Variable: Manipulation of the Independent Variable
Experimenter has some degree of control over the independent variable. It can be manipulated by him to whatever he wants it to be.
A variable that is expected to influence a dependent variable. Hypothesised to be the causal influence.
Alternative manipulations of the independent variable being investigated.
Group of subjects being exposed to the experimental treatment.
Group of subjects exposed to the control condition in an experiment – that is, not exposed to the experimental treatment.
By holding conditions constant, the researcher controls for potential sources of error in the experiment.
Steps in Experimental Research – 2) Decide on the Choice of Independent and Dependent Variable: Selection and Measurement of the Dependent Variable
Selection of the dependent variable is a crucial decision in designing an experiment as it determines what type of answer is given to the research question.
Variable to be predicted or explained. The standard by which the results of an experiment are judged; a variable expected to be dependent on the experimenter’s manipulation of the independent variable.
Steps in Experimental Research – 3) Select and Assign Test Units
Test units are subjects whose responses to experimental treatments are observed.
Random sampling error and sample selection error may occur in experiments so researchers have to choose and assign the subjects wisely.
Steps in Experimental Research – 3) Select and Assign Test Units: Randomisation
Procedure in which the assignment of subjects and treatments to groups is based on chance.
Allows true effects (if it exists) when overall repetitions of the experiment under the same conditions is conducted.
Steps in Experimental Research – 3) Select and Assign Test Units: Matching
Procedure for the assignment of subjects to groups that ensures each group of respondents is matched on the basis of pertinent characteristics.
Assures that subjects in each group are similar on the matched characteristics.
Steps in Experimental Research – 4) Address Issues of Validity in Experimemts
Major difference between experimental research and other research is experimenter’s ability to hold conditions constant and to manipulate the treatment.
Constancy of Conditions
Situations when subjects in experimental groups and control groups are exposed to situations identical except for different conditions of the independent variable.
When extraneous variables cannot be eliminated, experimenters may strive for constancy of conditions.
Technique used to control subjects’ knowledge of whether or not they have been given a particular experimental treatment.
Technique in which neither the subject nor the experimenter knows which are the experimental and which are the controlled conditions.
Error that occurs in the same experimental condition every time the basic experiment is repeated; a systematic bias.
Experiments are Judged By – Internal Validity
Validity determined by whether an experimental treatment was the sole cause of changes in a dependent variable or whether the experimental manipulation did what it was supposed to do.
If the experimental treatment was influenced by extraneous factors, the researcher will have problems making valid conclusions.
Extraneous Variables that may Jeopardise Internal Validity – History
History Effect: loss of internal validity caused by specific events in the external environment, occurring between the 1st and 2nd measurements that are beyond experimenter’s control.
Cohort Effect: change in dependent variable because members of 1 experimental group experienced historical situations that were different from members of other experimental groups.
Extraneous Variables that may Jeopardise Internal Validity – Maturation
Effect on the results of an experiment caused by experimental subjects maturing or changing over time.
Extraneous Variables that may Jeopardise Internal Validity – Testing
In a before-and-after study, the effect of pretesting may sensitive subjects when taking a test for the second time, thus affecting internal validity.
Extraneous Variables that may Jeopardise Internal Validity – Instrumentation
Effect on experiment results caused by a change in the procedures used to measure the dependent variable.
Extraneous Variables that may Jeopardise Internal Validity – Selection
Sampling bias that results from differential selection of respondents for the comparison group.
Extraneous Variables that may Jeopardise Internal Validity – Mortality (Sample Attrition)
Sample bias that results from the withdrawal of some subjects from the experiment before it is completed.
Extraneous Variables that may Jeopardise Internal Validity – Demand Characteristics
Experimental design procedures or situational aspects of an experiment that provide unintentional hints about the experimenter’s hypothesis to subjects.
Source of constant error as participants might act in a manner consistent with the experimental treatment.
Guinea Pig Effect
Effect on the results of an experiment caused by subjects changing their normal behaviour or attitudes in order to cooperate with an experimenter.
Unintended effect on the results of a research experiment caused by the subjects knowing that they are participants.
Experiments are Judged By – External Validity
Ability of an experiment to generalise beyond the data of the experiment to other subjects or groups in the population under study.
Problems of External Validity
The experimental situation may be artificial and may not represent the true setting and conditions in which the investigated behaviour takes place. It may still be valid if the researcher knows how to adjust results from an artificial setting to the marketplace.
Jeopardise External Validity – Internal Validity
Comparative norms may be established based on similar, previous studies so that the results can be projected beyond the experiment. If an experiment lacks internal validity, projecting results is not possible.
Experiments typically concern the identification of a single independent variable and the measurement of its effects on the dependent variable. Extraneous variables may affect the dependent variable, thereby distorting the experiment.
Steps in Experimental Research – 5) Select and Implement an Experimental Design
Next step is to decide on the type of experimental design.
Type of Experimental Design – Basic vs. Factorial Experimental Designs
Basic Experimental Designs a single independent variable is manipulated to observe its effect on a single dependent variable.
Factorial Experimental Designs are more sophisticated and allow for an investigation of the interaction of 2 or more independent variables.
Type of Experimental Design – Repeated Measures Or Not
Experimental technique in which the same subjects are exposed to all experimental treatment to eliminate any problems due to subject differences.
Research design that cannot be classified as a true experiment because it lacks adequate control of extraneous variables.
A scientific testing and controlled experimental procedure that provides an opportunity to measure sales and profit potential for a new product or to test a new marketing plan under realistic marketing conditions.
Advantage: no other research can beat the real world when it comes to testing.
Disadvantage: takes long to do it properly.
Test Marketing – 1) Decide Whether to Test Market Or Not
Test marketing is an expensive research procedure The value of the information must be compared with the costs of the research. Furthermore, there are uncertainties and risks with test marketing.
Often only used after other forms of research that proves the product to have a high probability of success.
Test Marketing – 2) Work Out the Functions of Test Market