Chapter 2- How Psychologists Do Research
What Makes Psychological Research Scientific?
1. Precision
Theory/Hunch→ Hypothesis→ Predictions with Operational Definitions→ Evidence
Theory- an organized system of assumptions and principles that purports to
explain a specified set of phenomena and their interrelations
Hypothesis- a statement that attempts to predict or to account for a set of
phenomena; scientific hypotheses specify relations among events or variables
and are empirically tested
Operational definition- a precise definition of a term is a hypothesis, which
specifies the operations for observing and measuring the process of
phenomenon being defined.
2. Skepticism- don’t accept ideas on faith/authority- show me!
3. Reliance on empirical evidence
4. Willingness to make “risky predictions”
Principle of Falsifiability- the principle that a scientific theory must make
predictions that are specific enough to expose the theory to the possibility of
disconfirmation; that is, the theory must predict now only what will happen but
what will not happen
Confirmation bias- the tendency to look for or pay attention only to information
that confirms one’s own belief
5. Openness- no secrecy, free flow of ideas, disclosure
Other scientists must be able to replicate and verify the results
These principles correspond to critical thinking guidelines
Peer review, where scientists submit their results to professional journals, which
send findings to experts in the field before deciding to publish them, ensures
that the work lives up to accepted scientific standards
Descriptive Statistics: Establishing the Facts
Representative sample- a group of individuals, selected from a population for study, which
matches the population on important characteristics such as age and sex
Descriptive methods- methods that yield descriptions of behaviour but not necessarily casual
explanations.
Case Studies
A detailed description of a particular individual based on careful observation or formal
psychological testing.
Commonly used by clinicians, also academic researchers
Most detailed picture of an individual
Drawbacks- information often missing or hard to interpret
Bias affects what is noticed vs. what is overlooked
Limited usefulness for deriving general behaviour principles
Used as sources of hypotheses, rather than tests Observational Studies
A study in which the researcher carefully and systematically observes and records
behaviour without interfering with the behaviour; may involve either naturalistic or
laboratory observation
Frist step in a program of research
Many participants
Count, rate or measure behaviour systematically
Naturalistic observation
Make sure not to be obvious- don’t want to be noticed
Find out how people/animals act in their normal social environment
Laboratory observation-
more control over situation
Bad in that it may cause people to behave differently
Observational studies more useful for describing than explaining
Tests
Psychological tests (assessment instruments) - procedures used to measure and evaluate
personality traits, emotional states, aptitudes, interests, abilities, and values
Objective tests/inventories measure beliefs, feelings or behaviours and individual is
aware of
Projective tests are designed to tap unconscious feelings or motives
Standardize- in test construction, to develop uniform procedures for giving and scoring a test
Norms- in test construction, established standards of performance
Reliability- in test construction, the consistency of scores derived from a test, from one time
and place to another
Test-retest reliability- given twice for same results
Alternate-forms reliability- given in two forms same results
Validity- the ability of a test to measure what it was designed to measure
Content validity- items broadly represent trait in question
Criterion validity- able to predict independent measures/criteria of the trait in question
Surveys
Questionnaires/ interviews that ask people directly about their experiences, attitudes, opinions
Volunteer bias- a shortcoming of findings derived from a sample of volunteers instead of a
representative sample; the volunteers may differ from those who did not volunteer.
Sampling problems an issue, people can lie
Technology can help with this- computer surveys
Risk because they don’t know if participants understand questions and take them
seriously Correlational Studies: Looking for Relations
Correlational study- a descriptive study that looks for a consistent relation between two
phenomena
Correlation- a measure of how strongly two variables are related to one another
Variables- characteristics of behaviour or experience that can be measured or described by a
numeric scale
Positive correlation- an association between increases in one variable and increases in another,
or between decreases in one and in another
Negative correlation- an association between increases in one variable and decreases in
another
Coefficient of correlation- a measure of correlation that ranges in value from -1.00 to +1.00
Illusory correlations- apparent associations between two things that are not really related
Correlation does not equal causation- just because two things are correlated, doesn’t
mean that one is causing the other or vice-versa
Ex. More churches in an area is correlated with more crime, doesn’t mean they
cause each other
Experiments: Hunting for Causes
Experiment- a controlled test of a hypothesis in which the researcher manipulates one variable
to discover its effect on another
Independent variable- a variable that an experimenter manipulates
Dependent variable- a variable that an experimenter predicts will be affected by manipulations
of the independent variable
Assigned to control group (no change in independent variable) or experimental group
(change independen
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