Causal research design – experimentation - VLE 6

Question 1

What is the ordinary meaning of causality?

Answer 1

X is the only cause of Y
.

X must always lead to Y

It is possible to prove that X is a cause of Y

Question 2

What is the scientific meaning of causality?

Answer 2

X is only one of a number of possible causes of Y

The occurrence of X
makes the occurrence of Y more probable (X is a probabilistic cause of Y).

We can never prove that X
is a cause of Y . At best, we can infer that X is a cause of Y.

Question 3

What is concomitant variation?

Answer 3

is the extent to which a cause, X, and an effect, Y, occur together or vary together in the way predicted by the hypothesis under consideration. The time order of occurrence condition states that the causing event must occur either before or simultaneously with the effect; it cannot occur afterwards. The absence of other possible causal factors means that the factor or variable being investigated should be the only possible causal explanation

Question 4

What is the time order of occurence condition?

Answer 4

The causing event must occur either before or simultaneously with the effect; it cannot occur afterwards.

Question 5

What is the absence of other possible causal factors condition?

Answer 5

The factor or variable being investigated should be the only possible causal explanation.

Question 6

What are independent variables?

Answer 6

Variables or alternatives which are manipulated and whose effects are measured and compared – for example, price levels.

Question 7

What are test units?

Answer 7

Test units are individuals, organisations or other entities whose response to the independent variables or treatments is being examined – for example, consumers or stores.

Question 8

What are dependent variables?

Answer 8

Dependent variables are the variables which measure the effect of the independent variables on the test units – for example, sales, profits and market shares.

Question 9

What are extraneous variables?

Answer 9

All variables other than the independent variables which affect the response of the test units – for example, store size, store location and competitive effort.

Question 10

What is an experimental design?

Answer 10

the test units and how these units are to be divided into homogeneous subsamples

which independent variables or treatments are to be manipulated

which dependent variables are to be measured

how the extraneous variables are to be controlled.

Question 11

What are X, O, R, symbols commonly used in market research?

Answer 11

X=
the exposure of a group to an independent variable, treatment or event, the effects of which are to be determined

O=
the process of observation or measurement of the dependent variable on the test units or group of units

R=
the random assignment of participants or groups to separate treatments.

Question 12

What is internal validity?

Answer 12

Internal validity refers to whether the manipulation of the independent variables or treatments actually caused the observed effects on the dependent variables. Control of extraneous variables is a necessary condition for establishing internal validity.

Question 13

What is external validity?

Answer 13

External validity refers to whether the cause-and-effect relationships found in the experiment can be generalised. To what populations, settings, times, independent variables and dependent variables can the results be projected?

Question 14

What is the trade-off between internal and external validity?

Answer 14

The artificial environment needed for internal validity hinders generalizability

Question 15

How can extraneous variables be classified?

Answer 15

History
Maturation
Testing effects
- main testing effect
- interactive testing effect
Instrumentation
Statistical regression
Selection bias
Mortality

History (H) refers to specific events which are external to the experiment but occur at the same time as the experiment.

Maturation (MA) refers to changes in the test units themselves which occur with the passage of time.

Testing effects are caused by the process of experimentation. Typically, these are the effects on the experiment of taking a measure on the dependent variable before and after the presentation of the treatment. The main testing effect (MT) occurs when a prior observation affects a later observation. In the interactive testing effect (IT), a prior measurement affects the test unit’s response to the independent variable.

Instrumentation (I) refers to changes in the measuring instrument, in the observers or in the scores themselves.

Statistical regression (SR) effects occur when test units with extreme scores move closer to the average score during the course of the experiment.

Selection bias (SB) refers to the improper assignment of test units to treatment conditions.

Mortality (MO) refers to the loss of test units while the experiment is in progress.

Question 16

How can extraneous variables be controlled for?

Answer 16

Randomisation
Matching
Statistical control
Design control

Randomisation refers to the random assignment of test units to experimental groups by using random numbers. Treatment conditions are also randomly assigned to experimental groups.

Matching involves comparing test units on a set of key background variables before assigning them to the treatment conditions.

Statistical control involves measuring the extraneous variables and adjusting for their effects through statistical analysis.

Design control involves the use of experiments designed to control specific extraneous variables.

Question 17

How can experimental designs be classified?

Answer 17

Pre-experimental
designs do not employ randomisation procedures to control for extraneous factors: the one-shot case study, the one-group pre-test-post-test design, and the static group.

In true experimental
designs, the researcher can randomly assign test units to experimental groups and treatments to experimental groups: the pre-test-post-test control group design, the post-test-only control group design, and the Solomon four-group design.

Quasi-experimental
designs result when the researcher is unable to achieve full manipulation of scheduling or allocation of treatments to test units but can still apply part of the apparatus of true experimentation: time series and multiple time series designs.

Statistical designs
are a series of basic experiments which allows for statistical control and analysis of external variables: randomised block designs, Latin square designs and factorial designs.

Question 18

What is a one shot case study?

Answer 18

A pre experimental design where A single group of test units is exposed to a treatment X. A single measurement on the dependent variable is taken (O1). There is no random assignment of test units. The one-shot case study is more appropriate for exploratory research than for conclusive research

Question 19

What is a one-group pre-test-post-test design

Answer 19

A pre experimental design. A one-group pre-test-post-test design can be represented symbolically as:

O1XO2.

A group of test units is measured twice. There is no control group. The treatment effect is computed as O2−O1 . The validity of this conclusion is questionable since extraneous variables are largely uncontrolled.

Question 20

What is a static group design?

Answer 20

Pre experimental design. In a static group, we have:

EG: XO1 and CG: O2.
A two-group experimental design. The experimental group (EG) is exposed to the treatment, and the control group (CG) is not. Measurements on both groups are made only after the treatment. Test units are not assigned at random. The treatment effect would be measured as O1−O2
.

Question 21

What is a pre-test-post-test control group design?

Answer 21

Pre experimental design. In a pre-test-post-test control group design, we have:

EG: RO1XO2andCG: RO3O4.

Test units are randomly assigned to either the experimental or the control group. A pre-treatment measure is taken on each group. The treatment effect (TE) is measured as:

(O2−O1)−(O4−O3).
Selection bias is eliminated by randomisation. The other extraneous effects are controlled as follows:

O2−O1=TE+H+MA+MT+IT+I+SR+MO
and:

O4−O3=H+MA+MT+I+SR+MO.
The experimental result is obtained by:

(O2−O1)−(O4−O3)=TE+IT.
Interactive testing effect is not controlled.

Question 22

What is the post-test-only control group design

Answer 22

A true experimental design.

EG: RXO1 and CG: RO2.

The treatment effect is O2−O1=TE. Except for pre-measurement, the implementation of this design is very similar to that of the pre-test-post-test control group design.

The Solomon four-group design explicitly controls for interactive testing effects, in addition to controlling for all the other extraneous variables.

Question 23

What is the key characteristic which distinguishes true experimental designs from pre-experimental designs?

Answer 23

The distinguishing feature of the true experimental design, as compared to the pre-experimental design, is randomisation. In true experimental designs, the researcher can randomly assign test units to experimental groups and also randomly assign treatments to experimental groups. Randomisation is the hallmark of objectivity.

Question 24

List the steps involved in implementing the post-test-only control group design.

Answer 24

Describe the design symbolically. The steps involved in implementing the post-test-only control group design are as follows.

1. Select a sample of participants at random.
2. Randomly assign the participants to two groups (i.e. experimental group and control group).
3. Participants in the experimental group would then be exposed to a treatment.

Post-treatment measurements are obtained from both groups using a measurement instrument like a questionnaire.
The design is described symbolically as follows:

EG: R X O1

CG: R O2.

The treatment effect is given by
TE: O1−O2.

Question 25

What are examples of quasi experimental designs?

Answer 25

A time series design involves a series of periodic measurements:

O1 O2 O3 O4 O5 O6 O7 O8 O9 O10.

There is no randomisation of test units to treatments. The timing of treatment presentation, as well as which test units are exposed to the treatment, may not be within the researcher’s control.

In a multiple time series design, we have:

EG: O1 O2 O3 O4 O5 X O6 O7 O8 O9 O10

and:

CG: O11 O12 O13 O14 O15 O16 O17 O18 O19 O20.

If the control group is carefully selected, this design can be an improvement over the simple time series experiment. We can test the treatment effect twice: against the pre-treatment measurements in the experimental group and against the control group.

Question 26

What are advantages of statistical designs?

Answer 26

The effects of more than one independent variable can be measured.

Specific extraneous variables can be statistically controlled.

Economical designs can be formulated when each test unit is measured more than once.

Question 27

When is randomised block testing useful?

Answer 27

A randomised block design is useful when there is only one major external variable, such as sales or store size, which might influence the dependent variable. The test units are blocked, or grouped, on the basis of the external variable. By blocking, the researcher ensures that the various experimental and control groups are matched closely on the external variable

Question 28

When is the Latin square design useful?

Answer 28

The Latin square design allows the researcher to statistically control two non-interacting external variables as well as to manipulate the independent variable.

Each external or blocking variable is divided into an equal number of blocks, or levels. The independent variable is also divided into the same number of levels. A Latin square is conceptualised as a table with the rows and columns representing the blocks in the two external variables. The levels of the independent variable are assigned to the cells in the table. The assignment rule is that each level of the independent variable should appear only once in each row and each column

Question 29

What is the factorial design for?

Answer 29

A factorial design is used to measure the effects of two or more independent variables at various levels. A factorial design may also be conceptualised as a table. In a two-factor design, each level of one variable represents a row and each level of another variable represents a column

Question 30

How is a multiple time series design different from a basic time series design?

Answer 30

The time series design involves a series of periodic measurements on the dependent variable for a group of test units. The treatment is then administered by the researcher or occurs naturally. After the treatment, periodic measurements are continued to determine the treatment effect. The multiple time series design is similar to the time series design except that another group of test units is added to serve as a control group. If the control group is carefully selected, this design can be an improvement over the simple time series experiment. The improvement lies in the ability to test the treatment effect twice: against the pre-treatment measurements in the experimental group and against the control group.

Question 31

What are the limitations of the Latin square design?

Answer 31

A Latin square design allows the researcher to control statistically two non-interacting external variables as well as to manipulate the independent variable. Each external or blocking variable is divided into an equal number of blocks or levels. The independent variable is also divided into the same number of levels. The limitations of the Latin square design are as follows.

• Such designs require an equal number of rows, columns and treatment levels.
• Only two external variables can be controlled simultaneously.
• They do not allow interactions of the external variables with each other or with the independent variable.

Question 32

What are limitations to experimentation?

Answer 32

Experiments can be time consuming, particularly if the researcher is interested in measuring the long-term effects.

Experiments are often expensive. The requirements of experimental group, control group and multiple measurements significantly add to the cost of research.

Experiments can be difficult to administer. It may be impossible to control for the effects of the extraneous variables, particularly in a field environment.

Competitors may deliberately contaminate the results of a field experiment.

Question 33

Should descriptive research be used for investigating causal relationships? Why or why not?

Answer 33

Descriptive research should not be used for establishing causal relationships for the following reasons.

It is difficult to establish the prior equivalence of the groups with respect to both the independent and dependent variables in descriptive research.

It is difficult to establish the time order of occurrence.

It provides little control in eliminating other possible causes.

Question 34

What is test marketing? What are the three types of test marketing?

Answer 34

Test marketing is an application of a controlled experiment done in a limited but carefully selected part of the marketplace called test markets. It involves a replication of a planned national marketing programme for a product in the test markets. The three types of test markets are as follows.

• Standard test market. The product is sold through regular distribution channels and, typically, the company’s own salesforce is responsible for distributing the product. It involves a one-shot case study.
• Controlled test market. The entire test-marketing programme is conducted by an outside research company, which also handles distribution and field sales operations in the test market.
• Simulated test market. Such markets are also called laboratory tests and yield mathematical estimates of market share based on initial reaction of consumers to the new product.

Question 35

What are the three types of test markets?

Answer 35

Standard test market. The product is sold through regular distribution channels and, typically, the company’s own salesforce is responsible for distributing the product. It involves a one-shot case study.

Controlled test market. The entire test-marketing programme is conducted by an outside research company, which also handles distribution and field sales operations in the test market.

Simulated test market. Such markets are also called laboratory tests and yield mathematical estimates of market share based on initial reaction of consumers to the new product.

Question 36

What is the main difference between a standard test market and a controlled test market?

Answer 36

In a standard test market, test markets are selected and the product is sold through regular distribution channels. Typically, the company’s own salesforce is responsible for distributing the product. Sales personnel stock the shelves, restock and take inventory at regular intervals. In a controlled test market, the entire test-marketing programme is conducted by an outside research company. The research company guarantees distribution of the product in retail outlets which represent a predetermined percentage of the market. It handles warehousing and field sales operations, such as stocking shelves, selling and stock control.