Theory Building

1
Theory Building

• Research Design
• Experimental Design
• Nonexperimental Design
• Formal Modeling
• Simulations

2
Research Design

• A research design is a plan of action for
  executing a research project, specifying
• The theory to be tested
• The unit of analysis
• The necessary observable data
• Data-collection procedures
• Analytical procedures

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Research Design

• The choice of research design is affected by
• The purpose of the research
• Resources like time, money, and skill or ethical
  concerns
• Every research design has positive and negative
  attributes
• You should match a design with your requirements

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Research Design

• All research designs attempt to
• Establish a relationship between two or more
  variables
• Demonstrate that the results are generally true
• Establish whether one phenomenon precedes another
  in time
• Eliminate as many alternative explanations as
  possible

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Research Design

• The goal of scientific research is to find causal
  relationships
• Causal relationships have three characteristics
• Covariation the alleged cause varies with the
  supposed effect
• Time order the cause precedes the effect in time
• Elimination of alternative explanations to
  isolate causation to one factor

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Research Design

• When choosing a research design, it is also
  important to consider
• Internal validity
• Refers to a causal relationship that was not
  created by a spurious relationship (a
  relationship in which a second independent
  variable influenced the dependent variable)
• External validity
• Refers to the extent to which the results of an
  experiment can be generalized across populations,
  time, and settings

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Experimental Design

• Experimental research designs are especially good
  for isolating causal factors
• Experimentation allows a researcher to make
  causal inferences with great confidence in the
  design through control over exposure to an
  experimental treatment
• But, although experiments have great internal
  validity, they suffer from weaker external
  validity

8
Experimental Design

• The classical randomized experiment has five
  basic characteristics
• At least one experimental group that will have
  exposure to the treatment and one control group
  that will not
• Randomly assigned individuals to each group,
  avoiding self-selection
• Controlled administration of the treatment,
  including the circumstances under which the
  experimental group is exposed
• Measurement of a dependent variable before and
  after the treatment with a pre-test and a
  post-test any difference between the tests can
  be attributed to the experimental effect of
  exposure to the treatment
• Controlled environment of the experiment (time,
  location, and other physical aspects)

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Experimental Design

• Post-test design
• Shares the characteristics of the classical
  randomized experiment, except that no pre-test is
  used because the sample is truly random and
  sufficiently large that one can assume that the
  control and experimental group(s) are equivalent

10
Experimental Design

• Repeated-measurement design
• Adds to the classic example additional pre-tests,
  post-tests, or both in an effort to measure
  longer-term effects of experimental treatments

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Experimental Design

• Multigroup design
• A modification of the classic example in which
  more than one experimental group is created to
  compare the effects of different treatments

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Experimental Design

• Field experiment
• An experiment in a natural setting in which the
  investigator does not have control over group
  membership but does have control over one or more
  independent variables
• Causal inferences made using this design are not
  as strongbut may be more practical for some
  situations

13
Nonexperimental Design

• Nonexperimental designs are characterized by at
  least one of the following
• Presence of a single group
• Lack of control over the assignment of subjects
  to groups
• Lack of control over the application of the
  independent variable
• Inability to measure the dependent variable
  before and after exposure to the independent
  variable occurs

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Nonexperimental Design

• Small-N designs
• Also called case studies or comparative cases
  studies
• Involve rich, deep understanding of a small
  number of cases
• May be used for exploratory, descriptive, or
  explanatory purposes

15
Nonexperimental Design

• Focus groups
• Can be used to create hypotheses for testing
  through other research designs
• Generally not used to establish causal
  relationships

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Nonexperimental Design

• Cross-sectional designs (survey, aggregate
  analysis)
• Characterized by measurements of the independent
  and dependent variables at approximately the same
  time
• Data analysis, rather than a treatment, is
  necessary for making causal inferences

17
Nonexperimental Design

• Longitudinal designs
• Allow for the measurement of variables at
  different points in time
• Can model change across time examine the time
  order of a causal relationship and estimate age,
  cohort, and period effects

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Nonexperimental Design

• Trend analysis
• Analysis of variables measured across periods of
  generally 20 years or more with a focus on
  explaining change over time

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Nonexperimental Design

• Panel studies
• Cross-sectional designs that include a time
  element
• Rely on measurement of the same units of analysis
  at different points in timecreating waves of
  data for analysis over time

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Nonexperimental Design

• Intervention analysis
• Measurements of a dependent variable before and
  after the introduction of an independent variable
  that is observed but not controlled by the
  researcher

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Nonexperimental Design

• Nonexperimental designs are generally
  characterized as having less internal reliability
  but better external validity than experimental
  designs
• There is always a tradeoff when moving from one
  design to another

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Formal Modeling

• Formal modeling and simulations involve
  techniques only remotely related to experimental
  and nonexperimental research designs

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Formal Modeling

• A formal model is a simplified and abstract
  representation of political realityexpressed
  through verbal, mathematic, or some other
  symbolic system
• A primitive term is undefined in a model, and
  its meaning is taken for granted.
• Assumptions are statements whose validity is
  taken for granted but are explicitly defined.
• Rules or logic govern connections between the
  parts of the model used for making deductions.
• Propositions are true by virtue of the rules used
  to deduce them.

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Formal Modeling

• Formal models rely on explicitly defined terms,
  so they lead to precise and clear thinking.
• Unambiguous and explicit rules and terms allow
  for verification of deductions by other
  researchers.

25
Simulations

• Simulations are a representation of a system to
  study its behavior over time
• Do not require any empirical verification
• Generally used with large systems like
  organizations with many integral components
• Rely on an analysis of change within the system
  over time based on highly detailed emergent
  properties of the system