Transcript Basic Elements of Criminal Justice Research

Learning Objectives
In this chapter you will learn about
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the elements of the research process
some basic research designs
program evaluation
the justification for following the steps in
the research process
Elements of the Research
Process
Basic elements of research include
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theory
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hypotheses
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a probabilistic statement about reality
a testable statement based on theory
variables
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constructs whose values vary
Validity & Reliability
Two key research concepts
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validity
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the accuracy of a measure
reliability
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the consistency of a measure across some
aspect, such as time
Validity
Four categories of validity
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internal
external
statistical conclusion
construct
The Research Process
Steps include
I. Problem Identification
II. Research Design
III. Data Analysis
IV. Interpretation and Presentation
of Results
Problem Identification
Problem identification includes
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Concepts
Hypotheses
Variables
Research Design
Research design includes
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Type of Design
Sampling Method
Data Collection
Sampling
Two broad categories of samples
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random (probability)
non-probability (available samples)
Results of research
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inferred from sample to population if
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sample is random (representative)
Data Collection
Data collection involves
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identification and selection of data
sources
sources include
original data (surveys, experiments, etc.)
 archival data (official records, official
data, etc.)
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Data Analysis
Data analysis involves
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Selection of Statistical Method
Calculation of Statistic
Interpretation of Statistic
Data Analysis
Data analysis involves
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entering the data into a database after
it is collected
selecting the proper method of
analysis, which depends on
the type of data collected
 the research question
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Interpretation & Presentation
Interpretation and presentation of
results involves
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a written summary of the results
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including policy implications, if any
presentation in a public forum
publication (if the results warrant it)
Elements of the Scientific
Method
Hypothesis
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formal statement about the expected
relationship between variables
Independent variable (X)
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produces an effect on the dependent
variable (Y)
Dependent variable (Y)
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may change due to the independent
variable
Elements
Directional hypothesis
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the independent variable is expected to
influence the dependent variable in a
specified direction – negatively or positively
Variable
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designed to measure observations or
concepts. It usually has more than one
possible value
The Classical Experiment
Classical or True Experimental Design
involves the assignment of subjects to
the experimental (receives the
treatment) and control groups
Random assignment
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every member of target population has an
equal chance of being selected for the
experimental or control group
Classical Experiment
The classical experimental design
R O1 X O2 Experimental Group
can be diagramed as illustrated
R O3
O4 Control Group
Where:
R = Random assignment
O1 and O3 are Pre-tests
O2 and O4 are Post-tests
X = treatment (I.V.)
Quasi-experimental Design
Quasi-experiments differ from classic
experiments
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lack an equivalent control group
may even lack any type of control
group – ex. one-shot case study
Quasi-experimental Design
O1 X O2 Experimental Group
O3
O4 Control Group
Where:
O1 and O3 are Pre-tests
O2 and O4 are Post-tests
X is the treatment (I.V.)
Evaluation Research
Evaluation research
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addresses the ability of a program or
policy to accomplish its goals
is action-oriented, policy research
is specifically designed to guide
decision making
Benefits of Research
Problem-solving focus
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provides direction for crime prevention
programs
promotes efficient utilization of resources
identifies what does and does not work
assists in decision to revise or eliminate
policies
Application of Research
Process
An example of applied research is
COMPSTAT
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using data analysis to identify key problems
dependent on the flow of information
dependent on accurate and timely
intelligence on crime and community
conditions
Summary
This chapter presented
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basic elements of research
a description of the “formula” that social
scientists and practitioners follow
a justification for following the formula
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obtaining valid and reliable data to use for
decision making