Experimental Methods Sept 13 & 14
Objective: Students will be able to explain and evaluate the
research methods used in psychology.
Agenda:
1. CBM
2. Reading Check
3. Finish Approaches notes
4. Research Methods notes
5. HW: Research methods chart, essay
Reading Quiz
1. The belief that after an outcome of an event that one
2.
3.
4.
5.
could have predicted that particular outcome.
Testable prediction usually implied by a theory.
Fair representation of a population because everyone
has an equal chance to participate.
The two elements in an experiment – one is the part
being manipulated, while the other is being measured.
(Must be in the correct order)
Clear statement of procedures which allows the process
to be replicated.
Basic Ideas
 Goal : Describe, predict, control & explain




behaviors
Theory
Hypothesis
Variables
Sampling
Naturalistic Observation
 Watch ONLY
 Used if other methods would be misleading
 Large amounts of data
 Problems:
 Change if known being observed
 See what expect
Case Studies
 Individuals/small groups
 Interviews, transcripts, tests
 Neuropsychology
Uses:
-Raw material
-Particular people
-Testing ground
Limitations:
-Limited evidence
-Not representative
Surveys
 Uses:
 Large amounts of data
 Limitations:
 Validity
 Wording
 Honesty
 Distortion
Experimental Method
Operational Definition – define exact
steps/methods used in research
 Controlled by
researcher
 Control group
 Independent variable
 Experimental group
 Item being manipulated
 Dependent variable
 Item being measured
and affected
 Receives no treatment
 Receives treatment
Experimental Method cont’d
 Confounding variable
 Any factor that affects
the dependent variable
in addition to or instead
of the independent
variable
 Random variable
 Uncontrolled/uncontroll
able factors
 Reliability
 Validity
 Experimenter bias
 Unintentional effect
that researcher may
have on results
 Placebo effect
 No benefit but helps
because believe it will
 Double blind design
 No one knows who gets
what
Ex Post Facto
 Manipulation has already occurred
 Use comparison groups
 Use groups that are in tact
 Explores possible causes and effects
 Focuses first on the effect, then attempts to
determine what caused the observed effect
Statistics
 Measures of central
tendency – typical
scores
 Mean
 Median
 Mode
Calculate the mean, median &
mode for the following numbers
4, 3, 7, 2, 5, 4, 4, 8
 Measures of variability
 Range
 Standard deviation
Correlation
 Correlation coefficient
 Positive Correlation
 Negative Correlation
 Correlation v. Causality
experiment
description
weakness
strength
scenario in
which this
method
could be
used
case study
naturalistic
observation
survey
Correlational
studies
Essay
Psychologists use a variety of research methods to study behavior.
Three of the main research methods used are

Case study
 Correlational Study, and
 Experiment
A. Discuss one advantage of each research method mentioned above.
B. Discuss one disadvantage of each research method mentioned above.
Pretend you are a psychologist who will use each of the three research
methods – case study, correlational study, and experiement – to
determine the effect of taking vitamin J on improving memory.
C. For each method listed above, explain a key characteristic of the basic approach
you could use to reach a scientific conclusion about the relationship between taking
vitamin J and improving memory. You need not design a complete study.