Chapter 2: The Research Enterprise in Psychology

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Chapter 2 The Research Enterprise in Psychology
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The Scientific ApproachA Search for Laws

• Basic assumption events are governed by some
  lawful order
• Goals
• Measurement and description
• Understanding and prediction
• Application and control

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Figure 2.1 Theory construction
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Figure 2.2 Flowchart of steps in a scientific
investigation
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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

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Table 2.1 Key Data Collection Techniques in
Psychology
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The Scientific Method Terminology

• 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 studys 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 GroupsThe Logic of the
Scientific Method

• Experimental group
• Control group
• 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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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
• When subjects serve as their own control group,
  the experiment is said to use a within-subjects
  design
• When two or more independent groups of subjects
  are exposed to a manipulation of an independent
  variable, the experiment is said to use a
  between-subjects design

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Experimental Designs Variations

• 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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Advantages and Disadvantages of Experimental
Research

• Strengths
• conclusions about cause-and-effect can be drawn
• Weaknesses
• artificial nature of experiments
• ethical and practical issues

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Descriptive/Correlational MethodsLooking for
Relationships

• Methods used when a researcher cannot manipulate
  the variables under study
• Naturalistic observation
• 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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Statistics and ResearchDrawing Conclusions

• Statistics using mathematics to organize,
  summarize, and interpret numerical data
• Descriptive statistics organizing and
  summarizing data
• Inferential statistics interpreting data and
  drawing conclusions

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Descriptive StatisticsMeasures 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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Figure 2.11 Measures of central tendency
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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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Figure 2.12 Variability and the 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

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Figure 2.13 Positive and negative correlation
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Figure 2.14 Interpreting correlation coefficients
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CorrelationPrediction, 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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Figure 2.15 Three possible causal relationships
between correlated variables
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Inferential StatisticsInterpreting Data/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

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Evaluating ResearchMethodological Pitfalls

• Sampling bias
• Placebo effects
• Distortions in self-report data
• Social desirability bias
• Response set
• Experimenter bias
• the double-blind solution

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Figure 2.16 The relationship between the
population and the sample
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Ethics in Psychological ResearchDo the Ends
Justify the Means?

• 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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Figure 2.17 Ethics in research
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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

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The Internet and Psychological Research

• 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