RESEARCH ENTERPRISE
IN PSYCHOLOGY
THE RESEARCH METHODS USED IN PSYCHOLOGY
GOALS OF THE SCIENTIFIC ENTERPRISE
• There are 3 interrelated goals
• 1: Measurement and description—how do we
measure the phenomenon
• 2: Understanding and prediction—hypothesis,
variables (measurable conditions—controlled or
observed)
• 3: Application and control—theories (bring
understanding from description and generates new
predictions)
STEPS IN A SCIENTIFIC INVESTIGATION
• 1: Formulate a testable hypothesis—variables must
be defined
• Operational definition describes actions or
operations that will be used to measure or control a
variable
STEPS
• 2: Select research method and design the study
• Depends on nature of the question
• Experiments, case studies, surveys, naturalistic
observation, etc…
STEPS
• 3: Collect the data
• How data is collected depends on what is being
investigated
STEPS
• 4: Analyze data and draw conclusions
• Statistics are used to analyze and determine the
validity of the hypotheses
STEPS
• 5: Report the findings
• Findings usually submitted to a journal: periodical
that publishes technical and scholarly material
ADVANTAGES OF THE SCIENTIFIC
APPROACH
• 1: It is clear and precise
• 2: Intolerant of error---findings are reviewed by
other skeptical researchers
EXPERIMENTAL
RESEARCH
EXPERIMENT
• Def: a research method where a variable is
manipulated under carefully controlled conditions
and observes changes in that variable
INDEPENDENT AND DEPENDENT
VARIABLES
• Ind. Variable: one that is changed to see its impact
on another variable (controlled or manipulated)
• Dep. Variable: one that is affected by manipulation
of the ind. variable
EXPERIMENTAL AND CONTROL
GROUPS
--Experimental Group: subjects who receive special
treatment in regard to the ind. variable
--Control Group: do not receive special treatment
--Both groups must be similar, except in treatment
EXTRANEOUS VARIABLES
• Def: any variables other than ind. variable that
seem to influence the dep. variable in a specific
study
• Even if groups are alike there are smaller differences
that could affect outcome
EXTRANEOUS VARIABLES
• Confounding of variables: when 2 variables are
linked together in a way that makes it difficult to sort
out their specific traits
• Makes it difficult to see which variable is affecting
the outcome
HOW TO PREVENT EXTRANEOUS
VARIABLES
• Random assignment: when subjects have an equal
chance of being assigned to any group or
condition in the study
VARIATIONS IN DESIGNING
EXPERIMENTS
• Sometimes it is good to use only one group
• Instead you create control conditions and
experimental conditions
VARIATIONS CONTINUED
• Manipulate more than one ind. variable in a single
experiment
• Allows researchers to see if two variables interact
VARIATIONS CONTINUED
• Use more than one dependent variable in a single
study
• Helps form a more complete picture
ADVANTAGES OF EXPERIMENTAL
RESEARCH
• Allows conclusions about cause and effect
relationships btwn variables
• Creates precise control
• Helps avoid extraneous variables
DISADVANTAGES OF EXPERIMENTAL
RESEARCH
• Experiments are artificial
• Experimental method can not be used in some
instances (ethics)
• Sometimes it is hard to manipulate variables
DESCRIPTIVE/
CORRELATIONAL
PERMITS RESEARCHERS TO DESCRIBE PATTERNS OF
BEHAVIOR AND DISCOVER LINKS BETWEEN VARIABLES
NATURALISTIC OBSERVATION
• Def: researcher observes w/o interfering directly
• Strength: experiments are less artificial
• Weakness: hard to remain unobtrusive
CASE STUDIES
•
•
•
•
Def: in-depth investigation of an individual subject
Includes: interviews, observation, testing
Good w/psych disorders
Problem: highly subjective
SURVEYS
• Def: use of questionnaires or interviews to gather
info. about specific aspects of a subject’s behavior
• Use to gather info. hard to observe
• Easy to gather from a large sample
ADVANTAGES OF
DESCRIPTIVE/CORRELATIONAL
RESEARCH
• Broadens scope of what can be studied
• Covers some of what can’t w/experimental
research
• Cannot control events
• Cannot demonstrate that 2 variables are casually
related
STATISTICS AND
RESEARCH
STATISTICS: USE OF MATHEMATICS TO ORGANIZE,
SUMMARIZE, AND INTERPRET NUMERICAL DATA
DESCRIPTIVE STATISTICS
• Used to organize and summarize data
• Include measure of central tendency, measures of
variability, and the coefficient of correlation
CENTRAL TENDENCY
• 3 measures:
1: Median: score that falls in the center of the
distribution of scores
2: Mean: avg. of scores (most useful)
3: Mode: most frequent score
VARIABILITY
• Def: how much the scores in a distribution vary from
each other and from the mean
• Standard of deviation: an index of the amount of
variability in a set of data
• Large variability = large standard of deviation
• Small variability = small s.o.d.
CORRELATION
• Def: when 2 variables are related to each other
• Correlation coefficient: numerical index of the
degree of relationship btwn 2 variables—indicates
direction of correlation and the strength of the
relationship
POSITIVE/NEGATIVE CORRELATION
• Positive(+): variables co-vary in the same direction
(Ex.: increased study time = increased test score)
• Negative(-): variables co-vary in opposite direction
(Ex.: increased absences = decreased test scores)
STRENGTH OF CORRELATION
• Size of coefficient indicates strength
• Coefficient varies btwn 0 and +1.00 (pos.); 0 and 1.00 (neg)
• Closer to zero, the weaker the relationship
CORRELATION AND CAUSATION
•Correlation does NOT
mean causation
INFERENTIAL STATISTICS
• Def: used to interpret data and draw conclusions
• Did chance play a factor?
• Statistical significance: exists when the probability
that the observed findings are due to chance is
very low (5 chances in 100)
EVALUATING RESEARCH
REPLICATION
• Def: repetition of a study
• To test results
• Can change results entirely
META-ANALYSIS
• Def: combines statistical results of many studies of
the same question, giving an estimate of the size
and consistency of a variable’s effect
• Allows to test the generalizability of findings across
people, places, and times and variations in
procedure in a precise and objective way
SAMPLING
• Sample: collection of subjects being observed in a
study
• Population: group from which the sample is taken
SAMPLING BIAS
• Def: exists when a sample is not representative of
the population from which it was drawn
PLACEBO EFFECT
• Def: occurs when participant’s expectations lead
them to experience some change even though
they receive empty, fake, or ineffectual treatment
DISTORTIONS IN SELF-REPORT DATA
• Questionnaires, inventories, interviews have flaws
• Social desirability bias: tendency to give socially
approved answers to questions about oneself
DISTORTIONS
• Response set: tendency to respond to questions in a
particular way that is unrelated to the content of
the questions
EXPERIMENTER BIAS
• Def: when researcher’s expectations about the
outcome of a study influence the results obtained
DOUBLE-BLIND PROCEDURE
• Def: research strategy in which neither subjects nor
experimenters know which subjects are in the
experimental or control groups
ETHICS
DO THE ENDS JUSTIFY THE MEANS?
QUESTION OF DECEPTION
• Deceiving in order to observe specific situations
• Proponents: “white lies”, not harmful to participants,
benefits worth it
• Critics: it is lying, may diminish trust, may produce
distress in subjects
ANIMAL RESEARCH
• Some treatments are unacceptable for humans
• Only 7-8% of all psychological studies involve
animals
• Very controversial