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Chapter 2

PS101 Chapter Notes - Chapter 2: Statistical Significance, Statistical Hypothesis Testing, Standard Deviation


Department
Psychology
Course Code
PS101
Professor
Lawrence Murphy
Chapter
2

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How Psychologists Do Research
The Ideal Scienst
1. Precision
Theory
o Organized system of assumpons & principles that aempts to explain
phenomena and how they are related
o As close to absolutely certain as possible
Hypothesis
o Statement that aempts to predict for a set of phenomena
o Empirically tested
o Used when uncertain
Operaonal denion
o Dene terms in hypotheses by specifying the operaon for observing &
measuring the process or phenomenon
o Theories generate hypothesis test hypothesis data facts theory
2. Scepsm
Sciensts do not accept ideas on faith/ authority
Treat conclusions, even old, with cauon
Cauon balanced with openness to new ideas & evidence
3. Reliance on Empirical Evidence (scienc)
Anecdotes are insucient
Gathered through various research methods
4. Willingness to Make “Risky Predicons”
Principle of falsiability
o A scienc theory must make predicons that are specic enough to disconrm
the theory science is falsiable
o Predicts what will and won’t happen
Conrmaon bias
o Tendency to seek & accept evidence that supports our theories & ignore
contradicng evidence
5. Openness
Explain the source of ideas, how they were tested and what the results were so that
replicaon is possible
The peer review process ensures scienc standards and provides a system of checks &
balances
Descripve Studies
Goal: to describe and predict behaviour but doesn’t allow casual explanaons
Essenal for all studies obtaining a representave sample
Methods: case studies, observaonal studies, psychological tests, surveys
o Case study: a detailed descripon of one person being studied or treated about
something specic
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Commonly used by clinicians
o Observaonal study: researchers systemacally observe & record behaviour without
interference
Naturalisc observaon: in normal social environment
Laboratory observaon: in a controlled lab seng
o Psychological test: procedures used to measure & evaluate personality traits, emoonal
states, aptudes, interests, abilies & values
Characteriscs of a good test:
Standardizaon
o When uniform procedures for giving & scoring tests exist
o Proper scoring refers to norms or established standards
Norms obtained by mass tesng on intended
populaons to determine di score ranges
Reliability
o The consistency of scores derived from a test from one me to
another (should generate the same results)
o Test-retest reliability
o Alternate-forms reliability
Having separate tests of generally the same quesons
Validity
o The ability of a test to measure what it was designed to measure
test should be relevant to the queson
o Face validity
Do the results generate what you expect it to?
Looks like a physics test when it is no hidden tricks
o Content validity
Do items broadly represent the test in queson?
o Criterion validity
Do the test results predict other measures of the trait?
o Survey:
Quesonnaires & interviews that ask people about experiences, atudes, or
opinions
Allow for extensive data collecon but many problems
Obtaining representave samples (volunteer bias the survey-takers
may already have an opinion prior to the survey not geng accurate
results, geng their opinions)
Truthfulness of responses
Type and phrasing of quesons
Correlaon Studies: a type of descripve study that looks for a relaonship between two phenomena
Measure of how strongly 2 quanable characteriscs of behaviour (variables) are related to
one another
Causaon: something happened because of one thing cause & eect
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