copyright © allyn & bacon 2007 chapter 2 research methods this multimedia product and its...

Copyright © Allyn & Bacon 2007

Chapter 2Chapter 2

Research Methods

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• ISBN: 0-131-73180-7


Why the Scientific Approach?Why the Scientific Approach?

Psychology is different from pseudosciences because it takes the scientific approach to its research. None of the pseudosciences have survived by the scientific method.

Psychologists reject approaches that claim to have “evidence” but offer only anecdotes and testimonials.


How Do Psychologists How Do Psychologists Develop New Knowledge?Develop New Knowledge?

Psychologists, like researchers in all other

sciences, use the scientific method to test their ideas

empirically


Empirical investigation – An approach to research that relies on sensory experience and observation as research data

How Do Psychologists How Do Psychologists Develop New Knowledge?Develop New Knowledge?

Scientific method –A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments


TheoryTheory

A theory is a testable explanation for a set of facts or observations.

Examples are: Einstein’s theory of relativity, germ theory of disease, Darwin’s theory of natural selection, social learning theory

Theory doesn’t just simply mean a “hunch” like in everyday language.


Emily Rosa and Therapeutic TouchEmily Rosa and Therapeutic Touch

Emily Rosa, a fourth grader, became the youngest published researcher.

Her science project challenged TT, a treatment that her mother (a nurse) had explained to her.

Emily used the scientific method to examine claims that TT could heal individuals.


The Five Steps of the Scientific MethodThe Five Steps of the Scientific Method

Developing a hypothesisDeveloping a hypothesis

Performing a controlled testPerforming a controlled test

Gathering objective dataGathering objective data

Analyzing the resultsAnalyzing the results

Publishing, criticizing, and Publishing, criticizing, and replicating the resultsreplicating the results


Developing a Developing a hypothesishypothesis

Performing a controlled test

Gathering objective data

Analyzing the results

Publishing, criticizing, and replicating the

results

Hypothesis –A statement predicting the outcome of a scientific study

Operational definitions –Exact procedures used in establishing experimental conditions and measurement of results



Developing a hypothesis

Performing a Performing a controlled testcontrolled test




results

Independent variable –The variable manipulated by the experimenter

Random presentation –Using chance alone to determine the order in which the stimulus is presented





Gathering Gathering objective dataobjective data



results

Data –Information gathered by researcher and used to test a hypothesis

Dependent variable –The measured outcome of a study; the responses of participants in a study






Analyzing the Analyzing the resultsresults


results

Based on statistical analyses of results, the hypothesis is accepted or rejected







Publishing, Publishing, criticizing, and criticizing, and replicating the replicating the

resultsresults


Researchers must find out whether their work can withstand the scrutiny of the scientific community


Types of Psychological ResearchTypes of Psychological Research

In experiments, the researcher controls all the conditions and directly manipulates the conditions

Non-experimental methods include:• Correlational studies…relationship between variables• Surveys…asking individuals to respond about self• Naturalistic observation…collect data unseen• Longitudinal studies…group is followed over time• Cross-sectional studies…one given time, different ages• Cohort-sequential studies…different ages followed brief time• Ex-post facto design…there is a condition due to ethics


Some terms involved in the experimental Some terms involved in the experimental method…method…

Basic inquiry

Hypothesis

Literature

Confounding or extraneous variables

Controls

Subject selection

Representative sample

Random assignment

Double-blind


Sources of BiasSources of Bias

Sources of bias include:Personal bias…beliefs, preferences, prejudices

Expectancy bias…looking for certain outcomes

Bias could affect the way an experimenter designs a study, collects data, or interprets results

Double blind studies attempt to control bias

Researchers must also attempt to control confounding variables


Ethics in ResearchEthics in Research

APA: “Ethical Principles of Psychologists and Code of Conduct”

Each institution must have IRB

Animal research must be approved by IACUC

Deception…some is fine but needs debriefing

Debriefing…study is explained and it should be made sure that individuals suffer no ill effects

Animal research…debate continues


Questions Science Cannot AnswerQuestions Science Cannot Answer

The scientific method is not appropriate for answering questions that cannot be put to an objective, empirical test• Ethics• Morality• Religious beliefs• Preferences


How Do We Make Sense of How Do We Make Sense of the Data?the Data?

Researchers use statistics for two major purposes:

(1) descriptively to characterize measurements made on groups

or individuals and(2) inferentially to judge whether

these measurements are the result of chance


Organizing the DataOrganizing the Data

First results must be arranged in a summary chart known as a frequency distribution

We can convert the data into a bar graph called a histogram


Describing the Data With Descriptive Describing the Data With Descriptive StatisticsStatistics

Descriptive statistics include:• The mean (measure of central tendency)—adding all scores

and dividing by the number of scores• The median (measure of central tendency)—the score that

separates the upper half of the scores from the lower half• The mode (measure of central tendency)—score that occurs

more often than all• The range (measure of variability)—difference between

highest and lowest values• The standard deviation (measure of variability)—average

difference between scores and the mean• The normal distribution—bell-shaped curve describing the

spread of scores…approximately 34% 34% 13% 13% 2% 2%


Correlations: A relationship between Correlations: A relationship between Two VariablesTwo Variables

Correlation–A relationship between two variables, in which changes in one variable are reflected in changes in the other variable

Correlation coefficient–A number between -1 and +1 expressing the degree of relationship between two variables


Making Inferences with inferential Making Inferences with inferential statisticsstatistics

Inferential statistics are used to assess whether the results of a study are significant or whether they might be simply the result of chance…this is usually the deciding factor whether or not to reject or accept a hypothesis

Statistical significance or difference—the probability that it might be due to chance is less than 5 in a 100…p<.05


End of Chapter 2End of Chapter 2

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