RESEARCH
METHODS
Chapter 2
Goals of Scientific Study
Measurement and Description - develop
measurement techniques that allow for the
description of behavior
Understanding and prediction – Hypothesis,
Variables
Hypothesis
Variables
Application and Control – Theory
(From describing behavior to understanding
behavior)

Steps in Scientific
Investigation
Advantages to a Scientific
Approach
Two major advantages:
Clarity and Precision
Relative intolerance of errors

Experimental Psychology
Experiment-manipulates a variable under carefully controlled
conditions and observes whether any changes occur in a
second variable
Cause and effect
independent variable – manipulating
dependent variable – measuring
experimental group - receive manipulation/treatment
Control group - do not receive manipulation/treatment
extraneous variables - likely to influence the dv(other than iv)

Experimental Psychology Con’t.



CONFOUNDING OF VARIABLES – TWO VARIABLES LINKED
TOGETHER
ADVANTAGES OF EXPERIMENTS:
CAUSE AND EFFECT RELATIONSHIPS
AVAILABILITY OF CONTROL
DISADVANTAGES OF EXPERIMENTS:
ARTIFICIAL
•The artificiality of the lab setting may influence
subjects’ behavior
Experimental Psychology Con’t.
UNEXPECTED AND EXTRANEOUS VARIABLES MAY
CONFOUND RESULTS


NOT ABLE TO GENERALIZE

CAN’T EXPLORE SOME RESEARCH QUESTIONS
Research Methods in
Psychology

Correlational Research
Research technique based on the naturally
occurring relationship between two or more
variables
 Often used to make predictions, such as the
relation between SAT scores and school success
 Cannot be used to determine cause and effect

Research Methods in
Psychology

Naturalistic Observation
 Systematic
observation in natural setting
 The main drawback is observer bias
 The
presence of an observer may alter the
participants’ behavior
Research Methods in
Psychology

Case Studies
 Detailed
description and analysis of one or a
few people
 Prominent in psychology
 Observer bias is a problem
 Unable to make generalizations past person
being studied
Research Methods in
Psychology

Surveys
 Questionnaires
or interviews, such as polls
prior to an election
 Can generate a lot of information for a fairly
low cost
 Questions must be constructed carefully so as
to not elicit socially appropriate answers
 Sampling biases can skew results
 Accuracy depends on ability and willingness of
participants to answer questions accurately
Statistics and Research


Descriptive statistics – organize and summarize data
Central Tendency – typical or average score
Mean-average – sensitive to extreme scores
Median-middle of distribution
Mode-most frequent score
Statistics and Research

Variability – scores vary from each other
 standard
deviation – index of the amount of
variation
 The lower the variation, the closer the scores are to
each other
How to get the SD (Example)

Your numbers:
3, 17, 5, 19, 7, 6, 5

Find the mean:
(3+17+5+19+7+6+5)/7 = 8.857

Find your deviations:
3-8.857 = -5.857; 17-8.857 = 8.143; 5-8.857 = -3.857;
19-8.857 = 10.143; 7-8.857 = -1.857; 6-8.857 = -2.857;
5-8.857 = -3.857

Square your deviations:
34.304, 66.308, 14.876, 102.88, 3.448, 8.162, 14.876
How to get the SD cont.

Add them up:
 34.304+66.308+14.876+102.88+3.448+8.162+
14.876 = 244.854

Divide by one less the total number of items:
 2.44.854/6

= 40.809
Find the Square
 √40.809
≈ 6.39
An example for the ages
Data

In this class, there are
20 students that range
from 15 to 18.




Math
15 = 3; 16 = 4; 17 = 8;
18 = 5
Mean Age: 16.75
Median: 17
Mode 17







(15-16.75)2 x 3 = 9.189
(16-16.75)2 x 4 = 2.252
(17-16.75)2 x 8 = .504
(18-16.75)2 x 5 = 7.815
Sum equals = 19.76
Divided by one less than
total students = 1.04
Finding the square root =
1.02
Curve looks like this!!!
Statistics and Research

Correlation – association between 2
variables
 correlational
coefficient – numerical index of
relationship between two variables
 Positive and Negative correlation
•
Closer the correlation to either -1.00 or +1.00 the
stronger the relationship. Coefficient near zero
indicates no correlation.
Statistics and Research

Correlation
 Positive
Correlation –Two factors that follow
the same direction
 I.e.,
- High SAT scores predict High school success
 I.e., - Low SAT scores predict Low school success
 Negative
Correlation. – Two factors that do not
follow the same direction
 I.e.,
- High SAT scores predicts Low school success
 I.e., - Low SAT scores predicts High school success
Inferential Statistics

Inferential statistics - interpret data and draw conclusions
Statistically significant – research results are unlikely to be
due to chance

Flaws In Evaluating Research
Replication – repetition to see if earlier results are duplicated

Sampling Bias – sample is not representative of the population

Sample-subjects selected

population-from where the sample is drawn

Placebo effects – participants expectations lead them to
experience some change; ineffectual treatment

Self-Report data:

Social desirability bias – socially approved answers

response set – response to questions in a particular
way/unrelated to content of question

Flaws In Evaluating Research
Con’t.
Experimenter Bias – researchers expectations influence
the results obtained
Double-blind procedure – neither subject or experimenter
know experimental or control group

Ethics & Guidelines
Humanitarian
II.
Informed Consent
III. Justification

Deception = see debriefing
IV. Right to Withdraw
V.
Risks and Benefits
VI. Debriefing
VII. Confidentiality
I.