Chapter 2

The Research Enterprise in Psychology – 8th Edition

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The Scientific Approach: A Search for Laws

Empiricism

Basic assumption: events are governed by some

lawful order

Goals:

– Measurement and description

– Understanding and prediction

– Application and control

Goal of theory testing in science: refutation not

proving – Karl Popper

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Figure 2.2

Five steps of

the Scientific

Method

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The Scientific Method: Terminology

Operational definitions are used to clarify precisely what is meant by each variable

Participants or subjects are the organisms whose behavior is systematically observed in a study

Data collection techniques allow for empirical observation and measurement

Statistics are used to analyze data and decide whether hypotheses were supported

Findings are shared through reports at scientific meetings and in scientific journals – periodicals that publish technical and scholarly material

– Advantages of the scientific method: clarity of communication and relative intolerance of error

Research methods: general strategies for conducting scientific studies

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Peer Review of Scientific Articles

The process of publishing scientific studies

allows other experts to evaluate and critique

new research findings.

They carefully evaluate each study’s

methods, statistical analyses, and

conclusions, as well as its contribution to

knowledge and theory.

The purpose of the peer review process is to

ensure that journals publish reliable findings

based on high-quality research.

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Figure 2.4 The peer

review process for

journal submissions.

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Experimental Research: Looking for Causes

Experiment = manipulation of one variable under controlled conditions so that resulting changes in another variable can be observed – Detection of cause-and-effect relationships

Independent variable (IV) = variable manipulated

Dependent variable (DV) = variable affected by manipulation – How does X affect Y?

– X= Independent Variable, and Y= Dependent Variable

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Experimental and Control Groups: The Logic of the Scientific Method

Experimental group – subjects who receive some special treatment in regard to the independent variable

Control group – similar subjects who do not receive the special treatment – Logic:

• Two groups alike in all respects (random assignment)

• Manipulate independent variable for one group only

• Resulting differences in the two groups must be due to the independent variable

Extraneous and confounding variables

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Youmans and Jee ( 2007)

Fudging the Numbers

IV: Candy condition

DV: Nine question evaluation of instruction form

Overall rating scores

Results: Significant difference in overall rating

Questions? Other effects and limitations

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Figure 2.6 The basic elements of an experiment

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Experimental Designs: Variations

Expose a single group to two different conditions

– Reduces extraneous variables

Manipulate more than one independent variable

– Allows for study of interactions between variables

Use more than one dependent variable

– Obtains a more complete picture of effect of the independent

variable

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Figure 2.7 Manipulation of two independent variables in an experiment

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Strengths and Weaknesses of Experimental Research

Strengths: – conclusions about cause-and-effect can be drawn

– Probabilistic causality

Weaknesses:

– artificial nature of experiments

– ethical and practical issues

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Descriptive/Correlational Methods: Looking for Relationships

Methods used when a researcher cannot manipulate

the variables under study • Naturalistic observation – Table 2.2, Levine & Norenzayan

(1999) – ranking of pace of life in 31 cultures

• Case studies

• Surveys

– Allow researchers to describe patterns of behavior and

discover links or associations between variables but cannot

imply causation

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Figure 2.10

Sample from a case

study – a descriptive

research method

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Statistics and Research: Drawing Conclusions

Statistics – using mathematics to organize,

summarize, and interpret numerical data

• Descriptive statistics: organizing and summarizing

data

• Inferential statistics: interpreting data and drawing

conclusions – use of probability

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Descriptive Statistics: Measures of Central Tendency

Measures of central tendency = typical or average

score in a distribution

Mean: arithmetic average of scores

Median: score falling in the exact center

Mode: most frequently occurring score

– Which most accurately depicts the typical?

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XX 2.11

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Descriptive Statistics: Variability

Variability = how much scores vary from each other

and from the mean

– Standard deviation = numerical depiction of variability

• High variability in data set = high standard deviation

• Low variability in data set = low standard deviation

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Descriptive Statistics: Correlation

When two variables are related to each other, they are correlated.

Correlation = numerical index of degree of relationship – Correlation expressed as a number between 0 and 1

– Can be positive or negative

– Numbers closer to 1 (+ or -) indicate stronger relationship

Table of Contents Figure 2.13 Positive and negative correlation

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Correlation: Prediction, Not Causation

Higher correlation coefficients = increased ability to

predict one variable based on the other

– SAT/ACT scores moderately correlated with first year

college GPA

2 variables may be highly correlated, but not causally

related

– Foot size and vocabulary positively correlated

– Do larger feet cause larger vocabularies?

– The third variable problem

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Inferential Statistics: Interpreting Data and Drawing Conclusions

Hypothesis testing: do observed findings support the

hypotheses?

– Are findings real or due to chance?

Statistical significance = when the probability that the

observed findings are due to chance is very low

– Very low = less than 5 chances in 100/ .05 level

– Other factors might account for the resultS

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Evaluating Research: Methodological Pitfalls

Sampling bias

Placebo effects – is not always uniform – cost

factors and perceived pain

Distortions in self-report data:

– Social desirability bias

– Response set

Experimenter bias

– the double-blind solution

– Research protocol of clinical trial for drugs – FDA in U.S.

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The Internet and Psychological Research

Internet-mediated research refers to studies in which

data collection occurs over the web.

Possible Advantages

– Samples that are much larger and much more diverse than

the samples typically used in laboratory research

– Have the potential to yield more diverse and representative

samples

Potential Disadvantages

– Sampling bias resulting from self-selection may be a more

troublesome issue in Internet-mediated research

• Web users tend to be younger, brighter, and more affluent than

nonusers

– Data are collected under far less controlled conditions than

in traditional studies

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Ethics in Psychological Research: Do the Ends Justify the Means?

Tuskegee Syphilis Study:

http://www.cdc.gov/tuskegee/timeline.htm

http://www.tuskegee.edu/global/story.asp?s=1207598

The question of deception

The question of animal research

– Controversy among psychologists and the public

Ethical standards for research: the American

Psychological Association

– Ensures both human and animal subjects are treated with

dignity

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XX 2.17

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Using databases

to access

research articles

PsychINFO –

psychological

literature 1887-

present

To access at UNA

http://www.una.edu/library

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Research Issues – Critical Thinking

Use of anecdotal evidence in psychology –

“I have a friend who…” p.74 – 75

Urban legends?

http://www.snopes.com