How Psychologists Do Research Introducing Psychology 11/23/2018 How Psychologists Do Research Chapter 2 Prepared by Krista Forrest, Ph.D These slides © 2006 Prentice Hall Psychology Publishing. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Copyright © 2007 Pearson Education Canada Chapter Outline What Makes Psychological Research Scientific? Descriptive Studies Correlational Studies Experiments Evaluating the Findings Keeping the Enterprise Ethical Copyright © 2007 Pearson Education Canada

What Makes Psychological Research Scientific? Introducing Psychology 11/23/2018 What Makes Psychological Research Scientific? Precision Skepticism Reliance on empirical evidence Willingness to make risky predictions Openness Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Precision Theories organized systems of assumptions that purport to explain phenomena and their interrelationships. Hypotheses attempt to predict or account for a set of phenomena; specify relationships among variables, and are empirically tested Operational definitions define terms in hypotheses by specifying the operations for observing and measuring the process or phenomenon Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Skepticism Scientists do not accept ideas on faith or authority Skepticism means treating conclusions, both old and new, with caution Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Reliance on empirical evidence Introducing Psychology 11/23/2018 Reliance on empirical evidence A scientist relies on empirical evidence to determine whether a hypothesis is true Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Willingness to make “risky predictions” Introducing Psychology 11/23/2018 Willingness to make “risky predictions” Principle of Falsifiability A scientific theory must make predictions specific enough to disconfirm the theory The theory must predict not only what will happen, but also what will not happen Confirmation bias Tendency to look for or pay attention only to information that confirms one’s own belief Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Openness Scientists must be willing to tell others where they got there ideas, how they tested them and what the results were Peer review, publishing and replicating research gives science a built in system of checks and balances Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Descriptive Studies: Establishing the Facts Introducing Psychology 11/23/2018 Descriptive Studies: Establishing the Facts Studies using methods that yield descriptions of behaviour but not necessarily causal explanations Include: Case studies Observational studies Psychological tests Surveys Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Case Studies A detailed description of a particular individual being studied or treated which may be used to formulate broader research hypotheses More commonly used by clinicians; occasionally used by researchers Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Observational Studies Introducing Psychology 11/23/2018 Observational Studies Researchers carefully and systematically observe and record behaviour without interfering with behaviour Naturalistic observation Purpose is to observe how people or animals behave in their natural environment Laboratory observation Purpose is to observe people or animals in a more controlled setting Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Psychological Tests Procedures used to measure and evaluate personality traits, emotional states, aptitudes, interests, abilities and values Psychological tests can be objective or projective Characteristics of a good test include: Standardization Reliability Validity Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Standardization The test is constructed to include uniform procedures for giving and scoring the test In order to score tests in a standardized way, an individual’s outcome or score is compared to norms To establish norms, the test is given to a large group of people who are similar to those for whom the test is intended By having norms or established standards of performance, we know who scores low, average, or high Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Reliability When constructing a test, the scores achieved on the test at one time and place should be consistent with the scores achieved at another time and place Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Validity The ability of a test to measure what it was designed to measure Content validity. The test broadly represents the trait in question Criterion validity. The test predicts other measures of same trait in question Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Surveys Questionnaires and interviews that ask people about experiences, attitudes, or opinions A representative sample Group of subjects, selected from the population for study, which matches the population on important characteristics such as age and sex Popular polls and surveys rely on volunteers Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Volunteer Bias Volunteers who participate may differ from those who did not volunteer Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Correlational Studies: Looking for Relations Introducing Psychology 11/23/2018 Correlational Studies: Looking for Relations A descriptive studies that look for a consistent relationship between two phenomena Correlation A statistical measure of how strongly two variables are related to one another Correlational coefficients can range from - 1.0 to 1.0 Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Variables Characteristics of behaviour or experiences that can be measured or described by a numeric scale Variables are manipulated and assessed in scientific studies Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Direction of Correlations Introducing Psychology 11/23/2018 Direction of Correlations Positive correlations An association between increases in one variable and increases in another, or decreases in one variable and decreases in another Negative correlations An association between increases in one variable and decreases in another Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Scatterplots Correlations can be represented by scatterplots Figure 1.2 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Explaining Correlations Introducing Psychology 11/23/2018 Start with 3 variables, (X, Y, & Z) where X and Y are correlated: X might cause Y Y might cause X X might be correlated with Y, which causes Z Correlations show patterns, not causes Figure 1.3 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Experiments: Hunting for Causes Introducing Psychology 11/23/2018 Experiments: Hunting for Causes A controlled test of a hypothesis in which the researcher manipulates one variable to discover its effect on another An experiment includes variables of interest, control conditions, and random assignment Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Experimental Variables Introducing Psychology 11/23/2018 Experimental Variables Independent variables are variables the experimenter manipulates Dependent variables are variables that the experimenter predicts will be effected by manipulations of the independent variable or variables Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Experimental & Control Conditions Introducing Psychology 11/23/2018 Experimental & Control Conditions In an experiment, a comparison condition in which subjects are no exposed to the same treatment as in the experimental condition In some experiments, the control group is given a placebo which is an inactive substance or fake treatment Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Random Assignment For experiments to have experimental and control groups composed of similar subjects, random assignment should be used Each individual participating in the study has the same probability as any other of being assigned to a given group Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Introducing Psychology 11/23/2018 Experimenter Effects Unintended changes in subjects behaviour due to cues inadvertently given by the experimenter Strategies for preventing experimenter effects include single and double-blind studies Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Evaluating the Findings Descriptive statistics Inferential Statistics Interpreting the Findings Copyright © 2007 Pearson Education Canada

Descriptive Statistics Introducing Psychology 11/23/2018 Descriptive Statistics Statistical procedures that organize and summarize research data Examples include: Arithmetic mean Standard deviation Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Inferential Statistics Introducing Psychology 11/23/2018 Inferential Statistics Statistical procedures that allow researchers to draw inferences about how statistically meaningful a study’s results are The most commonly used inferential statistics are significance tests Statistical tests that show how likely that a study’s results occurred merely by chance Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Interpreting the Findings Choosing the best explanation Judging the result’s importance Copyright © 2007 Pearson Education Canada

Choosing the Best Explanation Introducing Psychology 11/23/2018 Choosing the Best Explanation Interpretation of results may depend on how the research was conducted Cross-sectional studies involve subjects of different ages being compared at a given time Longitudinal studies involve subjects who are periodically reassessed over period of time Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Judging the Results’ Importance Introducing Psychology 11/23/2018 Judging the Results’ Importance Statistical techniques such as effect size and meta-analysis can help us determine if results are really important Effect size is the amount of variance among scores in the study accounted for by the independent variable Meta-analysis is a procedures for combining and analyzing data from many studies. It determines how much of the variance in scores across all studies can be explained by a particular variable Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

Keeping the Enterprise Ethical The ethics of studying human beings The ethics of studying animals Copyright © 2007 Pearson Education Canada

The Ethics of Studying Humans Introducing Psychology 11/23/2018 The Ethics of Studying Humans Informed consent Prospective participants should receive enough information to let them decide freely whether to participate Freedom to withdraw at any time Minimize discomfort Keep data confidential If deception is necessary, debriefing must occur Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall

The Ethics of Studying Animals Introducing Psychology 11/23/2018 The Ethics of Studying Animals Animals have always been used in a small percentage of psychological studies To conduct basic research To discover practical applications To study issues that cannot be studies experimentally with human beings To clarify theoretical questions To improve human welfare Copyright © 2007 Pearson Education Canada ©1999 Prentice Hall