THE RESEARCH METHODS USED IN PSYCHOLOGY

RESEARCH ENTERPRISE IN PSYCHOLOGY

GOALS OF THE SCIENTIFIC ENTERPRISE

• There are 3 interrelated goals• 1: Measurement and description—how do we

measure the phenomenon• 2: Understanding and prediction—hypothesis,

variables (measurable conditions—controlled or observed)• 3: Application and control—theories (bring

understanding from description and generates new predictions)

STEPS IN A SCIENTIFIC INVESTIGATION

• 1: Formulate a testable hypothesis—variables must be defined• Operational definition describes actions or

operations that will be used to measure or control a variable

STEPS

• 2: Select research method and design the study• Depends on nature of the question• Experiments, case studies, surveys, naturalistic

observation, etc…

STEPS

• 3: Collect the data• How data is collected depends on what is being

investigated

STEPS

• 4: Analyze data and draw conclusions• Statistics are used to analyze and determine the

validity of the hypotheses

STEPS

• 5: Report the findings• Findings usually submitted to a journal: periodical

that publishes technical and scholarly material

ADVANTAGES OF THE SCIENTIFIC APPROACH

• 1: It is clear and precise• 2: Intolerant of error---findings are reviewed by

other skeptical researchers

EXPERIMENTAL RESEARCH

EXPERIMENT

• Def: a research method where a variable is manipulated under carefully controlled conditions and observes changes in that variable

INDEPENDENT AND DEPENDENT VARIABLES

• Ind. Variable: one that is changed to see its impact on another variable (controlled or manipulated)• Dep. Variable: one that is affected by

manipulation of the ind. variable

EXPERIMENTAL AND CONTROL GROUPS

--Experimental Group: subjects who receive special treatment in regard to the ind. variable--Control Group: do not receive special treatment--Both groups must be similar, except in treatment

EXTRANEOUS VARIABLES

• Def: any variables other than ind. variable that seem to influence the dep. variable in a specific study• Even if groups are alike there are smaller

differences that could affect outcome

EXTRANEOUS VARIABLES

• Confounding of variables: when 2 variables are linked together in a way that makes it difficult to sort out their specific traits• Makes it difficult to see which variable is affecting

the outcome

HOW TO PREVENT EXTRANEOUS VARIABLES

• Random assignment: when subjects have an equal chance of being assigned to any group or condition in the study

VARIATIONS IN DESIGNING EXPERIMENTS

• Sometimes it is good to use only one group• Instead you create control conditions and

experimental conditions

VARIATIONS CONTINUED

• Manipulate more than one ind. variable in a single experiment• Allows researchers to see if two variables interact

VARIATIONS CONTINUED

• Use more than one dependent variable in a single study• Helps form a more complete picture

ADVANTAGES OF EXPERIMENTAL RESEARCH

• Allows conclusions about cause and effect relationships btwn variables• Creates precise control• Helps avoid extraneous variables

DISADVANTAGES OF EXPERIMENTAL RESEARCH

• Experiments are artificial• Experimental method can not be used in some

instances (ethics)• Sometimes it is hard to manipulate variables

PERMITS RESEARCHERS TO DESCRIBE PATTERNS OF BEHAVIOR AND DISCOVER LINKS BETWEEN VARIABLES

DESCRIPTIVE/ CORRELATIONAL

NATURALISTIC OBSERVATION

• Def: researcher observes w/o interfering directly• Strength: experiments are less artificial• Weakness: hard to remain unobtrusive

CASE STUDIES

• Def: in-depth investigation of an individual subject• Includes: interviews, observation, testing• Good w/psych disorders• Problem: highly subjective

SURVEYS

• Def: use of questionnaires or interviews to gather info. about specific aspects of a subject’s behavior• Use to gather info. hard to observe• Easy to gather from a large sample

ADVANTAGES OF DESCRIPTIVE/CORRELATIONAL

RESEARCH• Broadens scope of what can be studied• Covers some of what can’t w/experimental

research• Cannot control events• Cannot demonstrate that 2 variables are casually

related

STATISTICS: USE OF MATHEMATICS TO ORGANIZE, SUMMARIZE, AND INTERPRET NUMERICAL DATA

STATISTICS AND RESEARCH

DESCRIPTIVE STATISTICS

• Used to organize and summarize data• Include measure of central tendency, measures of

variability, and the coefficient of correlation

CENTRAL TENDENCY

• 3 measures:1: Median: score that falls in the center of the

distribution of scores2: Mean: avg. of scores (most useful)3: Mode: most frequent score

VARIABILITY

• Def: how much the scores in a distribution vary from each other and from the mean• Standard of deviation: an index of the amount of

variability in a set of data• Large variability = large standard of deviation• Small variability = small s.o.d.

CORRELATION

• Def: when 2 variables are related to each other• Correlation coefficient: numerical index of the

degree of relationship btwn 2 variables—indicates direction of correlation and the strength of the relationship

POSITIVE/NEGATIVE CORRELATION

• Positive(+): variables co-vary in the same direction (Ex.: increased study time = increased test score)• Negative(-): variables co-vary in opposite

direction (Ex.: increased absences = decreased test scores)

STRENGTH OF CORRELATION

• Size of coefficient indicates strength• Coefficient varies btwn 0 and +1.00 (pos.); 0 and

-1.00 (neg)• Closer to zero, the weaker the relationship

CORRELATION AND CAUSATION

•Correlation does NOT mean causation

INFERENTIAL STATISTICS

• Def: used to interpret data and draw conclusions• Did chance play a factor?• Statistical significance: exists when the

probability that the observed findings are due to chance is very low (5 chances in 100)

EVALUATING RESEARCH

REPLICATION

• Def: repetition of a study• To test results• Can change results entirely

META-ANALYSIS

• Def: combines statistical results of many studies of the same question, giving an estimate of the size and consistency of a variable’s effect• Allows to test the generalizability of findings

across people, places, and times and variations in procedure in a precise and objective way

SAMPLING

• Sample: collection of subjects being observed in a study• Population: group from which the sample is taken

SAMPLING BIAS

• Def: exists when a sample is not representative of the population from which it was drawn

PLACEBO EFFECT

• Def: occurs when participant’s expectations lead them to experience some change even though they receive empty, fake, or ineffectual treatment

DISTORTIONS IN SELF-REPORT DATA

• Questionnaires, inventories, interviews have flaws• Social desirability bias: tendency to give socially

approved answers to questions about oneself

DISTORTIONS

• Response set: tendency to respond to questions in a particular way that is unrelated to the content of the questions

EXPERIMENTER BIAS

• Def: when researcher’s expectations about the outcome of a study influence the results obtained

DOUBLE-BLIND PROCEDURE

• Def: research strategy in which neither subjects nor experimenters know which subjects are in the experimental or control groups

DO THE ENDS JUSTIFY THE MEANS?

ETHICS

QUESTION OF DECEPTION

• Deceiving in order to observe specific situations• Proponents: “white lies”, not harmful to

participants, benefits worth it• Critics: it is lying, may diminish trust, may

produce distress in subjects

ANIMAL RESEARCH

• Some treatments are unacceptable for humans• Only 7-8% of all psychological studies involve

animals• Very controversial