Copyright © 2010 Pearson Education Canada2-1 How Psychologists Do Research Chapter 2

Copyright © 2010 Pearson Education Canada2-2 Chapter Outline What Makes Psychological Research Scientific?What Makes Psychological Research Scientific? Descriptive StudiesDescriptive Studies Correlational StudiesCorrelational Studies ExperimentsExperiments Evaluating the FindingsEvaluating the Findings Keeping the Enterprise EthicalKeeping the Enterprise Ethical

What Makes Psychological Research Scientific? Key characteristics of the ideal scientist:Key characteristics of the ideal scientist: 1.Precision 2.Scepticism 3.Reliance on empirical evidence 4.Willingness to make “risky predictions” 5.Openness Copyright © 2010 Pearson Education Canada 2-3

Precision TheoryTheory –Organized system of assumptions & principles that purports to explain phenomena and how they are related HypothesisHypothesis –Statement that attempts to predict or account for a set of phenomena; specifies relationships; empirically tested Copyright © 2010 Pearson Education Canada2-4

Precision Operational definitionOperational definition –Define terms in hypotheses by specifying the operations for observing & measuring the process or phenomenon Copyright © 2010 Pearson Education Canada2-5

Scepticism Scientists do not accept ideas on faith or authorityScientists do not accept ideas on faith or authority Scepticism means treating conclusions, both old and new, with cautionScepticism means treating conclusions, both old and new, with caution Caution balanced with openness to new ideas & evidenceCaution balanced with openness to new ideas & evidence Copyright © 2010 Pearson Education Canada2-6

Empirical Evidence A scientist relies on empirical evidence to determine whether a hypothesis is trueA scientist relies on empirical evidence to determine whether a hypothesis is true Gathered through the use of various research methodsGathered through the use of various research methods Copyright © 2010 Pearson Education Canada2-7

“Risky Predictions” Principle of falsifiabilityPrinciple of falsifiability –A scientific theory must make predictions that are specific enough to disconfirm the theory –Predicts not only what will happen but also what will not happen Confirmation biasConfirmation bias –Tendency to seek and accept evidence that supports our theories & ignore evidence that contradicts beliefs Copyright © 2010 Pearson Education Canada2-8

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Openness Scientist’s willingness to explain the source of their ideas, how they tested them, and what the results wereScientist’s willingness to explain the source of their ideas, how they tested them, and what the results were –Enough clarity so replication possible Peer review process ensures scientific standards and provides system of checks & balancesPeer review process ensures scientific standards and provides system of checks & balances Copyright © 2010 Pearson Education Canada2-10

Descriptive Studies Goal to describe and predict behaviour but does not allow causal explanationsGoal to describe and predict behaviour but does not allow causal explanations Essential for all studies is obtaining a representative sampleEssential for all studies is obtaining a representative sample Descriptive methods:Descriptive methods: –Case studies, observational studies, psychological tests, surveys Copyright © 2010 Pearson Education Canada2-11

Case Studies A detailed description of a particular individual being studied or treatedA detailed description of a particular individual being studied or treated May be used to formulate broader research hypothesesMay be used to formulate broader research hypotheses Most commonly used by cliniciansMost commonly used by clinicians –Occasionally by researchers in preliminary stages of inquiry Copyright © 2010 Pearson Education Canada2-12

Observational Studies Method where researchers systematically observe & record behaviour without interferenceMethod where researchers systematically observe & record behaviour without interference –Naturalistic observation Observations in normal social environmentObservations in normal social environment –Laboratory observation Observations in a more controlled lab settingObservations in a more controlled lab setting Copyright © 2010 Pearson Education Canada2-13

Psychological Tests Procedures used to measure and evaluate personality traits, emotional states, aptitudes, interests, abilities, and valuesProcedures used to measure and evaluate personality traits, emotional states, aptitudes, interests, abilities, and values Psychological tests can be objective or projectivePsychological tests can be objective or projective Characteristics of a good test include:Characteristics of a good test include: –Standardization, reliability, validity Copyright © 2010 Pearson Education Canada2-14

Standardization A test is standardized when uniform procedures for giving & scoring test existA test is standardized when uniform procedures for giving & scoring test exist Proper scoring refers to norms or established standards of performanceProper scoring refers to norms or established standards of performance –Norms obtained by mass testing on intended populations to determine different score ranges (e.g., low, average, high) Copyright © 2010 Pearson Education Canada2-15

Reliability Reliability is the consistency of scores derived from a test from one time and place to the next or across scorersReliability is the consistency of scores derived from a test from one time and place to the next or across scorers –Test-retest reliability –Alternate-forms reliability Copyright © 2010 Pearson Education Canada2-16

Validity Validity is the ability of a test to measure what it was designed to measureValidity is the ability of a test to measure what it was designed to measure –Face validity –Content validity –Criterion validity Copyright © 2010 Pearson Education Canada2-17

Surveys Surveys are questionnaires & interviews that ask people about experiences, attitudes, or opinionsSurveys are questionnaires & interviews that ask people about experiences, attitudes, or opinions Allow for extensive data collection but many problems:Allow for extensive data collection but many problems: –Obtaining representative sample (volunteer bias) –Truthfulness of responses –Type and phrasing of questions Copyright © 2010 Pearson Education Canada2-18

Correlational Studies A correlational study is a type of descriptive study that looks for a relationship between two phenomenaA correlational study is a type of descriptive study that looks for a relationship between two phenomena Correlations:Correlations: –Measure of how strongly two quantifiable characteristics of behaviour (variables) are related to one another Copyright © 2010 Pearson Education Canada2-19

Types of Correlations Positive correlation:Positive correlation: –An association between increases in one variable and increases in another * Negative correlation:Negative correlation: –An association between increases in one variable and decreases in another Copyright © 2010 Pearson Education Canada2-20

Measuring Correlations Correlation coefficient:Correlation coefficient: –Statistical measure of correlation (ranges to +1.00) –Indicates size and direction of correlation –Often graphed using scatterplots Copyright © 2010 Pearson Education Canada2-21

Cautions about Correlations Correlations are often reported but may be small, nonexistent, or meaninglessCorrelations are often reported but may be small, nonexistent, or meaningless Correlations may be misleadingCorrelations may be misleading –Correlations do not establish causation! E.g., correlation between TV viewing and later attention problemsE.g., correlation between TV viewing and later attention problems Copyright © 2010 Pearson Education Canada2-22

Experiments A controlled test of a hypothesis in which the researcher manipulates one variable to discover its effect on anotherA controlled test of a hypothesis in which the researcher manipulates one variable to discover its effect on another An experiment includes:An experiment includes: –Variables of interest, control conditions, random assignment, and consideration of experimenter effects Copyright © 2010 Pearson Education Canada2-23

Experimental Variables Independent VariableIndependent Variable –Variable that experimenter manipulates Dependent VariableDependent Variable –Variable that experimenter predicts will be affected by manipulations of the independent variable Copyright © 2010 Pearson Education Canada2-24

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Conditions Experimental groupExperimental group –Participants in an experiment who are exposed to the manipulation of the independent variable Control groupControl group –Participants in an experiment who are not exposed to the manipulation of the independent variable –May involve a placebo or “fake“ treatment –Forms a control condition for comparison Copyright © 2010 Pearson Education Canada2-26

Random Assignment In order for experiments to have groups that are similar on key characteristics, must use random assignmentIn order for experiments to have groups that are similar on key characteristics, must use random assignment –Procedure for assigning people to experimental & control groups in which each individual has the same probability as any other of being assigned to a given group Copyright © 2010 Pearson Education Canada2-27

Experimenter Effects Unintended changes in participants behaviour due to cues inadvertently given by experimenterUnintended changes in participants behaviour due to cues inadvertently given by experimenter Prevent biases through single- or double-blind studiesPrevent biases through single- or double-blind studies Copyright © 2010 Pearson Education Canada2-28

Advantages & Limitations Advantages:Advantages: –Experiments allow conclusions about cause & effect –Help to detect real effects and strong empirical evidence Limitations:Limitations: –Participants may not be representative –Laboratory situations may be artificial (alternative of field research) Copyright © 2010 Pearson Education Canada2-29

Evaluating the Findings Once data is collected, psychologists evaluate results in three ways:Once data is collected, psychologists evaluate results in three ways: 1.Describe them 2.Assess how reliable & meaningful they are 3.Figure out how to explain them Accomplish this by descriptive & inferential statistics, and interpretationAccomplish this by descriptive & inferential statistics, and interpretation Copyright © 2010 Pearson Education Canada2-30

Descriptive Statistics Statistical procedures that organize and summarize research data (e.g., graphs & charts)Statistical procedures that organize and summarize research data (e.g., graphs & charts) Use arithmetic mean & standard deviationUse arithmetic mean & standard deviation Copyright © 2010 Pearson Education Canada2-31

Inferential Statistics Statistical procedures that allow researchers to draw inferences about how statistically meaningful a study’s results areStatistical procedures that allow researchers to draw inferences about how statistically meaningful a study’s results are Most common are significance testsMost common are significance tests –Indicate how likely a result occurred by chance –When likelihood is low, result is said to have statistical significance Copyright © 2010 Pearson Education Canada2-32

Interpreting Findings Determine meaning by using hypotheses and theories to explain how the results of research fit togetherDetermine meaning by using hypotheses and theories to explain how the results of research fit together Involves choosing the best explanation & judging the importance of the resultsInvolves choosing the best explanation & judging the importance of the results Copyright © 2010 Pearson Education Canada2-33

Choosing the Best Explanation Interpretation may depend on type of study:Interpretation may depend on type of study: Cross-sectional studies: participants of different ages compared at a given timeCross-sectional studies: participants of different ages compared at a given time Longitudinal studies: participants periodically reassessed over a period of timeLongitudinal studies: participants periodically reassessed over a period of time Copyright © 2010 Pearson Education Canada2-34

Judging Importance Statistical techniques may be used to determine if results are really importantStatistical techniques may be used to determine if results are really important –Effect size is a measure of how much variability among scores is accounted for by the independent variable –Meta-analysis combines data from many studies; how much variance in scores across all studies is accounted for by a particular variable Copyright © 2010 Pearson Education Canada2-35

Keeping the Enterprise Ethical 1.Respect for human dignity 2.Respect for free & informed consent 3.Respect for vulnerable persons 4.Respect for privacy & confidentiality 5.Respect for justice & inclusiveness 6.Balancing harms and benefits 7.Minimizing harm 8.Maximizing benefit Copyright © 2010 Pearson Education Canada2-36 Eight major ethical principles: Eight major ethical principles:

Ethics of Studying Humans Must provide informed consentMust provide informed consent Freedom to withdraw at any timeFreedom to withdraw at any time Minimize discomfortMinimize discomfort Keep data confidentialKeep data confidential If deception is necessary, must provide debriefing about true nature of studyIf deception is necessary, must provide debriefing about true nature of study Copyright © 2010 Pearson Education Canada2-37

Ethics of Studying Animals Animals used in psychological research for many reasons:Animals used in psychological research for many reasons: –To conduct basic research; discover practical applications; study issues that cannot be studied experimentally with humans; clarify theoretical questions; improve human welfare Must abide by ethical codes for humane treatment of animalsMust abide by ethical codes for humane treatment of animals Copyright © 2010 Pearson Education Canada2-38

End of Chapter 2 Copyright © 2010 Pearson Education Canada2-39