scientific method and research design

7/31/2019 Scientific Method and Research Design

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Scientific Methods

and Research Design


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Scientific MethodAccording to Karl Pearson, there are three distinct characteristics of the scientific method

Careful and accurate classification of facts and

observation of their correlation and sequence

The discovery of scientific laws with the aid of the

creative imagination

Self-criticism and the final touchstone of equal validity

for all normally constituted minds


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Comparison of scientific method and non-scientific method

The scientific method is more objective as compared to the

non-scientific method

The scientific method is more precise than the non-scientific

method

The scientific method takes cognizance of the existing

knowledge in a particular field, carries out further

investigations in it and compares the results with those

obtained earlier


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Research Design

Research design is the plan, structure, and strategy of investigation

conceived so as to obtain answers to research questions and to control

variance. ...Kerlingerthe blue print of the collection, measurement and analysis of data. It

aids the scientist in the allocation of his limited resources by posing

crucial choices-is the blueprint to include experiments, interviews,

observation, the analysis of records, stimulation, or some combination of

these? Are the methods of data collection and the research situation to be

highly structured? Is an intensive study of a small sample more effective

than a less intensive study of a larger sample? Should the analysis be

primarily or qualitative?

...Bernard S. Phillips

A research design is the specification of methods and procedures for

acquiring the information needed. It is the over-all operational pattern or

framework of the project that stipulates what information is to be

collected from which sources by what procedures. Green and Tull


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Research Design

ExploratoryDescriptive Causal


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EXPLORATORY RESEARCH

The focus is on the discovery of ideas.

In a business where sales have been

declining for the past few months,

the management may conduct a

quick study to find out what couldbe the possible explanationsthe

sales might have declined on

account of a number of factors, such

as the deterioration in the quality of

the product, increased competition,

inadequate or ineffective

advertising, lack of efficient and

trained salesman or use of the

wrong channels of distribution.


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Characteristics of Exploratory Research


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EXP

LORATORYRESEARC

H

SECONDARY DATA

EXPERIENCE SURVEY

FOCUS GROUP STUDY

CASE STUDY

T

YPESOFEXPLORATORYRES

EARCH


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DESCRIPTIVE RESEARCH

When the researcher wants to know the characteristics of certain

groups such as age, sex, educational level, occupational level,

occupation or income, a descriptive study may be necessary.

When the researcher wants to know the proportion of people in a

given population who have Behaved in a particular manner,

making projections of a certain thing; or determining the

relationship Between two or more variables.

The objective of such a study is to answer the who, what,when, where, and how of the subject under investigation.

Descriptive studies are well-structured and tends to be rigid and

its approach cannot be changed every now and then.


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Cross-sectional Studies Longitudinal

Descriptive Study


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Cross-

sectionalstudies

A cross-sectional study is concerned with a sample of elements from a given

population. For example-households, dealers, retail stores, or other entities.

It is of two types

Field Study

Survey

A major strength of survey research is its wide scope.

It is economical as more information can be collected per

unit of cost.

It is less time consuming.

Generally, survey research does not penetrate below the surface as more

emphasis is given to the extent of info sought rather than to an in-depth

analysis.

Another disadvantage is that survey demands more time and more money

when it is conducted on a large scale.Another limitation of survey is that the interview may make the respondent

alert and cautious and he may not answer the questions in a natural manner.

Finally, researcher needs to be knowledgeable as he must know the

technicality of constructing good questionnaires, interviewing the

respondents, editing, coding and tabulation of data and the statistical

techniques to analyze the data.


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Longitudinal Studies

It is based on panel data and panel methods.

A panel is sample of respondents who are interviewed and then

reinterviewed from time to time.

ADVANTAGES

Such data enable the researcher to undertake detailed analysis. Thus, one candetermine the characteristic of individuals who have changed brands and those who

have not.

Re interview of the families means that they have provided their acceptance to such

study which ensures to collect more comprehensive data.

As such collected data is more accurate than survey method.

Cost of data collection is lower than in case of personal interviews.

DISADVANTAGES

A major criticism of panels is that they may not be representative samples.

Another limitation is reporting of wrong data.


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CAUSAL DESIGNS

A causal design investigates the cause and effect

relationship between two or more variables.

Suppose a company ABC Ltd. managed to sold 1 million units

of shampoo bottles in 2010 and 1.5 million units in 2011. In

year 2011 he also launched a promotional campaign of this

product. Now ABC Ltd. wants to know was the increase in

sales in 2011 due to that promotional campaign?

The design of causal research is based on reasoning along well tested lines.

John Stuart Mill formulated a set of principles based on logic for causal

research. The principles are the method of agreement, the method of

negative agreement and the method of concomitant variation.


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CAUSAL DESIGNS

The method of agreement says that when two or more cases of a

given phenomenon have one and only one condition in common,

then that condition may be regarded as the cause (or effect) of the

phenomenon

ZCA B

ZEDC

ZCTherefore

If

and


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CAUSAL DESIGNS

Mills second principle is the negative canon of agreement which states that

when conditions non-C is found to be associated with observation non-Z, we

may hold that a causal relationship exists between C and Z.

The method of agreement and the negative canon of agreement form the basis

of a third method known as the method difference. This method states that

when there are two or more cases, and in one of them observation Z can be

made, while in the other it cannot; and if factor C occurs when observation Z is

made and does not occur when observation Z is not made, then one can say that

C and Z have a causal relationship.

ZCA B

Non

Z

Non

CDC

ZCTherefore

produce

produce

produce


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CAUSAL DESIGNS

ill recognized one more method known as the method of concomitant variation.

It states that if a change in the amount of one

variable is accompanied by a comparable change in

the amount of another variable in two or more cases,

and the latter change does not occur in the absence of

the first change, one change is the cause (or effect) ofthe other.


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CAUSAL INFERENCE STUDIES

Natural Experiments Controlled Experiments

It can be of two types

The main distinction lies in the degree of intervention

and manipulation exercised by the researcher.

High intervention

and manipulation

Less intervention

and manipulation

involves involves

f l i


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Types of Natural Experiments

Time-series & Trend

Designs

Cross-Sectional

DesignsCombination of Two

In a time-series design, data are obtained from the same sample or population at

successive intervals from a panel of individuals or households.

Trend data relate to matched samples drawn from the same population at successive

intervals.

Thus there is no continuity in the sample in trend designs as a result of which data can

be analyzed in the aggregate form.


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Types of Time-series and Trend Designs

The One-Shot Case Study Known as Try-Out design

Consider this example-

Where X indicates the exposure of a subject or group to an

experimental treatment whose effect is to be observed, and O

indicates the observation or measurement taken on the subjector group after an experimental treatment. Suppose that we

provide training to a group of salesmen (X) for a certain

period and then measure the sales effected by this group of

salesmen (O).

X O


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Before-after without control group It has a prior measurement as well


O-1 X O-2

or

O-1 O-2 O-3 X O-4 O-5 O-6


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Multiple Time-Series It involves control group


O-1 O-2 O-3 X O-4 O-5 O-6

and

O-1 O-2 O-3 X O-4 O-5 O-6

Control Group

Experimental Group


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Cross Sectional Designs

In cross-sectional designs, the effect of different

levels of treatments are measured on severalgroups at the same time.


X-4

X-1

X-2

X-3

O-1

O-2

O-3

O-4

Cross-sectional designs are used when varying levels of advertising is done for the same product

but in different territories or when varying prices are fixed in different territories. The impact of

varying levels of treatment is studied on the basis of the sales of the product in differentterritories.


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Combination of Cross Sectional and Time-Series Designs

These designs, as the name implies, combine the time-series and

cross-sectional designs. While there can be many variants, a more

frequently used design is the ex-post-facto test-control group. Thedesign can be shown symbolically as follows and is well suited to

continuous panel data:

O-1

O-2

O-3

O-4

X


A certain advertisement (X) is run and panel members are then asked if they had seen it

earlier. Those who had may constitute a test or experimental group and those who had

not form the control group. It may be noted here that the experimental and control

groups would not be known until after the advertisement was run. The impact of the

advertisement is measured by comparing the differences in purchases made by theexperimental and control groups before and after the advertisement.

Hi t m th before d after m m t t


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ontrolledExperim

ents History may cause the before and after measurements todiffer. There may be certain developments during the

intervening period as a result of which the two measurements

may not be comparable.

The second factor is maturation which signifies biological

and psychological changes in the subject which take place

with the passage of time.

The third factor is the pre-testing which may affect the

internal validity of the before-after design.

Finally, variation in measurement may cause variations in the

before and after measurements and these may be taken as the

effect of the experimental variable.

The foregoing limitations indicate the

need for a control group against whichthe results in the experimental group

can be compared.


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ontrolledExperim

ents In controlled experiments, two kinds of intervention on the

part of the researcher are required.

The first relates to the manipulation of at least oneassumed independent or causal variable so that the effect

of one or more treatments on the experimental variables

can be measured.

The second intervention relates to the assignment of

subjects to experimental and control groups on a random

basis so that the effect of extraneous factors can be

controlled. As the size of the experimental and the

control group increases, the effect of extraneous factors

on these groups can be equalized or balanced by using a

random selection procedure.


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Sources

of

Experimental

Error

History

Maturatio

n

Premeasurement

Effect

Interactive

Testing

Effect

Instrumentation

SelectionBias

StatisticalRegression

Mortality

Criteria of Good Research Design


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Criteria of Good Research Design

The main criterion of a research design is

that it must answer the research questions.

To do this, it is necessary that proper

hypotheses be formulated otherwise there

may be a lack of congruence between the

research questions and hypotheses.

The second criterion relates to control of

independent variablesboth the

independent variables of the study as also

extraneous independent variables.

The third criterion is generalisability. Towhat extent can we generalize the results

of the study?

scientific method and research design

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