Transcript Chapter 1: Scientific Understanding of Behavior

Research Methods:
Midterm Review
Dr. Dodge
February 28, 2006
Introduction to
Research
What is Scientific Research?
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“Scientific research is systematic,
controlled, empirical, and critical
investigation of natural phenomena
guided by theory and hypotheses
about the presumed relations
among such phenomena.”
Kerlinger
The Scientific Method and the
Empirical Approach
The fundamental characteristic of the
scientific method is empiricism
(knowledge based on observations).
 Most importantly, the scientific
method embodies a number of rules
for collecting, evaluating, and
reporting data (observations put into
measurable form).
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Goals of Scientific Research
1. To Describe Behavior
2. To Predict Behavior
3. To Determine the Causes of
Behavior
4. To Understand or Explain Behavior
- In order to accomplish these goals,
scientific research can be conducted
in ways that are both basic and
applied
Basic vs. Applied Research
Neither type of research is superior
to the other
 The progress of science depends on
the synergy between the two
 Both may cause the other to be
modified
 Both use the scientific method of
research
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Evidence-Based Practice
A Hierarchy of Levels of
Best Evidence
Level 1 evidence: strong evidence from at
least one systematic review of multiple
well-designed randomized controlled trials.
 Level 2 evidence: strong evidence from at
least one properly designed randomized
controlled trial of appropriate size.
 Level 3 evidence: evidence from welldesigned trials without randomization,
single group pre-post, cohort, time series,
or matched case-controlled studies.
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A Hierarchy of Levels of
Best Evidence
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Level 4 evidence: evidence from welldesigned non-experimental studies from
more than one center or research group.
Level 5 evidence: opinions of respected
authorities, based on clinical evidence,
descriptive studies, or reports of expert
committees
Which level(s) should we strive for in our
research?
Meta-Analysis
Meta-analysis: method used to review
research literature based on statistical
integration and analysis of research
findings
 In meta-analysis, the DV is the effect size
(i.e., the outcomes or results of each study
selected for review transformed into a
common metric across studies) and the IV
are study characteristics (i.e., participants,
interventions, and outcome measures).
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Meta-Analysis
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Benefits of meta-analysis:
•Synthesize the results from many
studies succinctly and intuitively for
nonscientific communities,
•Illustrate the amount and relative impact
of different programs on different criteria
for policy decision-making purposes, and
•Identify the most effective programs and
highlight gaps or limitations in the
literature to suggest directions for future
research
Research Ethics
Areas of Focus in Research
Ethics
Harm
Informed
Consent
Confidentiality
Deception
Reporting Results and Plagiarism
The Scientific Method
Science
Testing ideas empirically according to
a specific set of procedures that is
open to public inspection
 Based on objectively observed
evidence
 Without personal beliefs,
perceptions, biases, attitudes or
emotion
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The Scientific Method
The Scientific Method
Step 1: Observation
 Step 2: Form a hypothesis
 Step 3: Use hypothesis to generate a
testable prediction
 Step 4: Design the study
 Step 5: Conduct the study
 Step 6: Perform hypothesis testing
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APA Style *
* Refer to Dr. Pruett’s PowerPoint!
Quantitative and
Qualitative Approaches
Observing Behavior
Behavior can be observed or
measured.
 Because behavior varies so much,
scientists need to have numerous
ways to measure and observe
behavior in both experimental and
non-experimental settings.
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Research Perspectives

Two major theoretical perspectives
underlie much of social science research:
• a. the positivist tradition, which “seeks
facts or causes of social phenomena
apart from the subjective states of
individuals”
• b. the phenomenological perspective,
which “is committed to understanding
social phenomena from the actor’s own
perspective”
Research Perspectives
Quantitative Research
• generally stems from a positivist
tradition
 Qualitative Research
• generally follows the
phenomenological tradition
 Both, in theory, are valid!
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Quantitative Research
Quantitative research: Data are
collected and observations are
reported numerically.
 Questionnaires, tests, and other
measures to record frequency of
behavior, occurrence of behavior
and/or duration of behavior
 After numerical data are collected,
they are analyzed statistically.
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Qualitative Research
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Qualitative Research: Data are
collected from observations and
interviews
Data often expressed in non-numerical
terms using language and images –
analyzed systematically
Summaries of discussions, interviews,
and video- or audio-taping of behaviors
Quantitative vs. Qualitative
Design
Quantitative
Research Designs:
Experimental
Quasi-Experimental
Ex post facto
Correlational
Descriptive
Time Series/Single
Subject
Qualitative
Research Designs:
Ethnographic
Case study
Phenomenological
Historical
Philosophical
Grounded Theoretical
Quantitative vs. Qualitative
Summary
Neither is superior to the other
 Choosing one or the other is
based on what is needed in your
study
 High quality research projects
may incorporate aspects of both
approaches.
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Introduction to
Qualitative Research *
* Refer to Dr. Simpson’s PowerPoint!
Introduction to Statistics
Statistics and Research
Design
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Statistics: Theory and method of
analyzing quantitative data from samples
of observations in order to help make
decisions about hypothesized relations.
Statistics are merely tools used in
research design!
Research Design: Plan and structure of
the investigation to answer the research
questions (or hypotheses)
Statistics
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There are two types of statistics
• Descriptive Statistics: involves
tabulating, depicting, and describing
data
• Inferential Statistics: predicts or
estimates characteristics of a population
from a knowledge of the characteristics
of only a sample of the population
Statistics & Parameters
• Parameter: a value, usually unknown
(estimated), used to represent a certain
population characteristic
• Statistic: a quantity that is calculated
from a sample of data. Used to give
information about unknown values in the
corresponding population.
Descriptive Statistics
• Nominal scales
 No numerical or quantitative
properties. A way to classify
groups or categories.
 Gender: Male and Female
• Ordinal scales
 Used to rank and order the levels
of the variable being studied. No
particular value is placed between
the numbers in the rating scale.
 Restaurant Ratings: 4 Stars, 3
Stars, 2 Stars, and 1 Star
Descriptive Statistics
• Interval scales
 Difference between the numbers on the
scale is meaningful and intervals are
equal in size. NO absolute zero. Allows
for comparisons
 Temperatures on a thermometer
• Ratio scales
 Scales that do have an absolute zero
point than indicated the absence of the
variable being studied. Can form ratios.
 Weight: 250 pounds is ½ of 500 pounds
Descriptive Statistics
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Frequency Distributions
• Constructed by summarizing data in
tables according to the number or
frequency of observations in each
category, score, or score interval
• Data can be concisely summarized in
bar graphs, histograms, or frequency
polygons
Descriptive Statistics
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Measures of Central Tendency
• Mode
 Most frequently occurring score
• Median
 Score that divides a group of scores in
half.
• Mean
 Preferred whenever possible and is the
only measure of central tendency that is
used in advanced statistical calculations
 An average of all scores. Add up scores
and divide by total number of scores.
Descriptive Statistics
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Measures of Variability
• Range
 Calculated by subtracting the lowest score from
the highest score.
 Used only for Ordinal, Interval, and Ratio scales
• Variance
 The extent to which individual scores in a
distribution of scores differ from one another
• Standard Deviation
 The square root of the variance
 Most widely used measure to describe the
variation of a set of observations in a
distribution.
Descriptive Statistics
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Correlation
• Statistical summary of the degree or
magnitude and direction of the
relationship or association between two
variables
• Correlations can be positive or negative
Linear Regression
• Make predictions on a new sample of
observations from the findings on a
previous sample
Inferential Statistics:
Sampling
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Degree to which those surveyed are
representative of a specific population
Sampling frame: set of people who have
the chance to respond to the survey
External validity: degree to which the
sample frame corresponds to the
population to which the researcher wants
to apply the results
Inferential Statistics:
Sampling
Two basic types: probability and nonprobability
 Probability sampling: including
random sampling
 Non-probability sampling: including
convenience sampling
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Response Rates
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Most government-sponsored surveys require
response rates of 75%
A response rate of 70% is very good, 60% is
good, and 50% is adequate
Post-cards, follow-up letters, and telephone
calls are used to increase the response rates
Results of non-response bias can be
examined by comparing those who respond
early with those who respond after follow up
Questions?