Transcript Types of Inferential Statistics

Research Design & Analysis 1:
Class 4 (section B)
• Announcements
– lab due dates
– new lab section
– S.M.I.L.E.
• Stuff fire alarm edited out …
• Asking questions (Lab assignment)
• Introduction to non-experimental research
methods
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New Lab Section
We have added a new section PSYC2010 LC1
Thursday 3:00-4:30
HSH 016
Starting this week
Please (some of you) move to this section...
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S.M.I.L.E.
The Sensory Motor Instructional Leadership Experience (SMILE)
Program is in its seventeenth year of operation. In the past,
Acadia students from every faculty on campus have volunteered
to give instruction in physical activity to children with "special
needs" in Kings County on a weekly basis. The instructor/child
ratio is one-to-one and the experience has been a very positive
one for all involved. Last term over 200 Acadia students provided
instruction for 180 children every week.
AN ORIENTATION MEETING WILL BE HELD ON
Thursday, September 23rd, 1999 at 6:00 p.m.
BAC 244
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Scientific explanations
• Empirical - based on objective observations that are
verifiable by others
• Rational - follows rules of logic and consistent with
known facts (data)
• Testable - through direct observations of from specific
predictions
• Parsimonious
• General (ideally)
• Tentative
• Rigorously evaluated
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HIERARCHIAL OVERVIEW:
The science of psychology (based on text)
1. To build an organized body of knowledge about its subject matter
2. To develop explanations for phenomena within its domain
HOW?
RESEARCH
STEP 1
STEP 2
STEP 3
Identify problem to study
Discover information about problem
Develop explanation for problem
Authority method
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Rational method
Scientific Method
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SCIENTIFIC METHOD
RESEARCH PROCESS
STEP 1
Observe problem
1. Develop testable hypothesis
STEP 2
Formulate possible explanation
2. Choose the proper design
STEP 3
Make further observations
to eliminate alternate expalnations
3. Choose and obtain subjects
STEP 4
Retest and refine
4. Conduct study
5. Analyse results
6. Report results
Reported results produce more questions
More questions renews research process.
Repeated research process increase overall
knowledge base.
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Research
Process
Figure from
text
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Overview
• Overall scientific purpose - to build knowledge
base.
• Knowledge base built by research.
• Best way to research - scientific method.
• Scientific method is carried out in 6 steps called
the “Research Process.”
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Asking Questions
“I can’t think of anything!”
“Where can I get ideas?”
“How do I know what has already been
done?”
“How do I know if I have a good question?”
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I can’t think of any!
“Yes you can!”
• doesn’t have to be perfect
• doesn’t have to sound “scientific”
• doesn’t have to be totally original
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Where can I get ideas?
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Observe other people
Observe yourself (introspection)
Focus on a practical problem
Theory
Expand on your own research
Look at what others have already done
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How can I find out what has already been done?
Primary and secondary sources...
• Books
• Journals
– Psychological abstracts
– Psychinfo
– Interlibrary loan
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Reading journal articles
• Abstract
• Introduction
• Method
– subjects
– materials
– procedures
• Results
• Discussion
• References
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Is it a good (scientific) question?
The “ROTI” Test
• Is it Repeatable (replicable)?
• Is it Observable (empirical)?
• Is it Testable (falsifiable)?
• Is it Important?
– plausible
– justifiable
– makes a contribution
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Are these good questions?
• Are beagles smarter than poodles?
• What do dogs dream about?
• Are there racial differences in the size of newborn
male penises?
• Would the U.S. have entered WWII if Japan
hadn’t bombed Pearl Harbor?
• Is God dead, as Nietzche proposes?
• When in excruciating pain, do people prefer Coke
or Pepsi?
• Do artists scratch their left or their right ears
more?
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Turning questions into hypotheses
• Hypotheses are falsifiable statements
– Poperian Science
• Make best guess
– H0 (Null) vs Hexp (Experimental hypotheses)
• State the nature of the relationship
between two (or more) variables
• State expected difference between two (or
more) groups
– directional or non-directional
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Choosing a research design
Are you interested in causal or correlational
relationships?
While correlation doesn't imply causation,
causation does imply correlation
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Introduction to scientific methods:
Non-experimental research
• characteristics of non-experimental research
• types of non-experimental research
• what you can learn from these methods
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Characteristics of non-experimental
research
• Observe but don’t manipulate
• Lack of control over extraneous variables
Terminology
Extraneous variables: not directly interested in
but which might influence the results of your
study
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Types of non-experimental research
• Observational research
– naturalistic observation
– participant observation
• (e.g., Rosenham, 1973)
– content analysis
• Archival research
• Survey research
– questionnaires (written)
– interviews (oral)
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What you can determine/learn
• Co-occurrence of variables
– correlation
• Ability to make predictions
– regression
– predict criterion variable from predictor
variable
• Causality still unknown
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What you cannot determine
If there is a causal relationship between
variables
• third variable problem
– number of appliances and children
– male pattern baldness and heart disease
• directionality problem
– health and lice (New Hebrides)
– watching TV violence and aggression
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Why use these designs?
• Can be useful in early stages of a research
program
• Interested in relation among variables in the
“real world”
• Only interested in predicting behaviour (vs.
understanding causal relations)
• Experimental methods not possible
– Organismic variables
– Ethics
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Correlations (and regressions)
• Correlational statistics can be applied to any
type of design (including experimental)
• Correlational design occurs when we do not
randomly assign participants to the level of
either variable - i.e., levels of variables are
not manipulated.
• Can use correlation/regression statistics with
either manipulated predictor variables or
natural variation.
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Correlation coefficients
• Measure the direction and degree of
association.
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Drawing conclusions from correlational designs
Have concerns with directionality, and there are
usually many extraneous variables so causality
can not be inferred
but
Correlational designs can be used to:
– discover relations
– to solve ethical and practical problems
– to study relations under natural conditions (provide
greater external/ecological validity)
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Introduction to scientific methods:
Experimental research
• Experimentation Involves manipulation of
variables
• Experimentation involves control over
extraneous variables
– Holding extraneous variables constant
– Randomizing effects of extraneous variables
• Quasi-experimental (Ex-post-facto) designs
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