Experimental Research Design: Understanding Laboratory, Field, and Natural Experiments, Lecture notes of Research Methodology

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EXPERIMENTATION

A RESEARCH METHODOLOGY

PRESENTED BY –

Ms. Mallika Rao

AND

Ms. Shweta Shah

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Research Methods in Architecture

Ms. Mallika Rao & Ms. Shweta Shah

WHAT IS AN EXPERIMENTAL RESEARCH DESIGN?^ WHAT IS AN EXPERIMENTAL RESEARCH DESIGN?  ANP / DSC 500

The purpose of experimental research design is toenable the researcher to credibly establish a cause-effect relationship 

Many studies illustrate how experimental method is usedto separate alternative explanations and test them 

The special nature of the experiment is that they arealways conducted under controlled conditions in asystematic way in which an artificial situation is createdand events which generally go together are pulled apart

Ms. Mallika Rao & Ms. Shweta Shah

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TYPES OF EXPERIMENTS^ TYPES OF EXPERIMENTS

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Laboratory Experiments –^ - most common carried out in a specially created setting^ - experimenter able to control wide variety of extraneous variables 

Field Experiments –^ - researcher manipulates the independent variables but does so ina field i.e. outside environment where only the setting differs 

Natural Experiments – termed as

Quasi - Experiments

• are studies which take advantage of experiment like situationsthat arise as a result of social policy or events in nature. - independent variable not directly under the control of theinvestigator^ - subjects are neither randomly assigned nor matched in groups

Ms. Mallika Rao & Ms. Shweta Shah

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COMPONENTS OF AN EXPERIMENTAL METHOD

PLAN

COMPONENTS OF AN EXPERIMENTAL METHOD

PLAN

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Participants 

Elements and factors 

Setting 

Instruments and materials 

Procedures and measures 

Statistical analysis 

Experimenter

Ms. Mallika Rao & Ms. Shweta Shah

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PARTICIPANTS- ASSIGNMENT^ PARTICIPANTS- ASSIGNMENT

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If random assignment is made,indicate how it is made. 

Identify other controls in the experimental design that willsystematically control the variables that might influencethe outcome.

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Use of covariates and statistical control

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Use of subgroups

Ms. Mallika Rao & Ms. Shweta Shah

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PARTICIPANTS- NUMBER^ PARTICIPANTS- NUMBER

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Number of participants in each group. 

Systematic procedures for determining the size of eachgroup. 

Power analysis (Lispey, 1990) to identify the appropriatesample size for groups.

• Level of statistical significance -^

Amount of power desired

-^

The effect size

Ms. Mallika Rao & Ms. Shweta Shah

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VARIABLES^ VARIABLES

Variables - Elements and factors under consideration 

Any characteristic or quality which differs in degree orkind and can be measured 

Have values or levels of measure. For eg. Height,running speed, age etc.

Ms. Mallika Rao & Ms. Shweta Shah

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VARIABLES – VARIOUS TYPES^ VARIABLES – VARIOUS TYPES

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Continuous variables 

Categorical variables 

Combination of both 

Dependent variables 

Independent variables 

Extraneous variables All are associated with the subjects, the experimenter, the

settings and the experimental procedure itself

Ms. Mallika Rao & Ms. Shweta Shah

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INSTRUMENTS AND MATERIALS^ INSTRUMENTS AND MATERIALS

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Choice 

Development 

Items 

Scales 

Reports of reliability 

Validity of scores on past uses 

Any permissions needed to use them 

Pilot test of materials

Ms. Mallika Rao & Ms. Shweta Shah

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IMPORTANT TERMINOLOGY^ IMPORTANT TERMINOLOGY

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Experimental group

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A subject group exposed to the independent variable.

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Also called the treatment group 

Control group

• A subject group which resembles the experimental group

in every way except that it is not exposed to theindependent variable.

Ms. Mallika Rao & Ms. Shweta Shah

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TYPES OF EXPERIMENTAL DESIGN^ TYPES OF EXPERIMENTAL DESIGN

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Pre- experimental design

X--------- O

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True experiments

Group A: R-----O------X-------O Group B: R------O---------------O

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Quasi experiments

Group A: O------X-------O Group B: O---------------O

X: exposure of a group to an experimental variable O: observation or measurement recorded on an instrument R: random assignment

Ms. Mallika Rao & Ms. Shweta Shah

ANP / DSC 500

STATISTICAL ANALYSIS^ STATISTICAL ANALYSIS

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Descriptive statistics calculated for observations andmeasures at the stages of the experiment 

Means, standard deviations and ranges 

Inferential statistical tests used to examine thehypotheses in the study

Ms. Mallika Rao & Ms. Shweta Shah

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LIMITATIONS^ LIMITATIONS

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Although this methodology allows the researcher animpressive amount of control over variables , it is chieflylimited by its artificiality 

Conditions in the laboratory may be different from thosein the real world and people may react and responddifferently 

Some behavioral issues are not suitable forexperimentation for ethical reasons or for cost