The Ways and Means of

Psychology

STUFF YOU SHOULD

ALREADY KNOW BY NOW IF YOU

PLAN TO GRADUATE

The Scientific Method in Psychology

3 major types of scientific research

(1)Naturalistic observations

(2)Correlational studies

(3)Experiments

What is the Scientific Method?

A set of rules that govern the collection and analysis of date gained through observational studies and experiments

5 steps of scientific method(1) Identify the problem and formulate

hypothetical cause-and-effect relations among variables.

(2) Design the experiment.(3) Perform the experiment.(4) Evaluate the hypothesis by examining the

data from the study .(5) Communicate the results.

Getting an Idea for Research: Where do Good Ideas Come From?

• Hypothesis = a tentative statement about a cause and effect relationship between two or more events

• Theory = a set of statements designed to explain a set of phenomena

• Naturalistic observation = studying creatures in their natural environment

Designing an Experiment

• Variables = a measure capable of assuming any of several values

• 2 groups:(1) Experimental group = a group of subjects in an

experiment, the members of which are exposed to a particular value of the independent variable, which has been manipulated by the experimenter

(2) Control group = a comparison group used in an experiment, the members of which are exposed to the naturally occurring or zero value of the independent variable

What are the variables?

The independent variable is that which is manipulated in an experiment as a means of determining cause-and-effect relations.

The dependent variable is the event whose value is measured in an experiment.

The manipulation of the independent variables should demonstrate whether they affect the value of the dependent variable.

Nominal Fallacy

The false belief that one has explained the causes of phenomenon by identifying and naming it.

Operational Definitions

The definition of a variable in terms of the operations the experimenter performs to measure or manipulate it.

Validity = the degree to which the operational definition of a variable accurately reflects the variable it is designed to measure or manipulate

Control of Independent Variables

We need to be sure that we are only manipulating the value of the independent variable.

• Confounding variables = inadvertent alteration of more than one variable during an experiment

Counterbalancing prevents confounding of independent variables with time-dependent processes.

Performing an Experiment

• What subjects will be used?

• What instructions will be given?

• What equipment and materials will be used?

Reliability of Measurements

The repeatability of a measurement; the likelihood that if the measurement was made again it would yield the same value

Factors affecting Reliability:(1) Conditions of experiment(2) Degree of subjectivity(3) Interrater reliability

Selecting the Subjects

Random assignment = an assignment of subjects to the various groups of an experiment by random means, thereby ensuring comparable groups

Subjects’ Expectations

• Some subjects will purposely cooperate or not cooperate or try to figure our the question being asked.

• Single-blind study = only the experimenter knows the value of the IV

• Double-blind study – neither experimenter nor subject knows the value of the IV

Correlational Studies

• Used in which experimenter cannot manipulate variables (i.e. gender, income)

• In each member of a group of people we measure two or more variables as they are found to exist, and we determine whether the variables are related.

• Often done to investigate the effects of personality variables on behavior

Correlations do not necessarily indicate cause-and-effect relations.

Matching

A systematic selection of subjects in groups in an experiment or a correlational study to ensure that the mean values of important subject variables of the groups are similar.

Used to study effects of a variable that can’t be altered

Single-Subject Research

An experiment or correlational study concerning the behavior of individual subjects rather than comparisons of the average performance of groups of subjects

Individuals can serve as their own controls.

• Case study = observation of the behavior of individuals having special characteristics, such as psychological or neurological disorders

• Retrospective study – a research technique that requires subjects to report what happened in the past

Generality

The ability to conclude that the results obtained from a sample apply also to the population from which the sample was taken.

Sample = a selection of items from a larger population

APA Guidelines• Treat subjects with respect• Do not coerce subjects• Give participants opportunity to withdraw• Obtain informed consent before participation

Informed consent = agreement to participate as a subject in an experiment after being informed about the nature of the research and any possible adverse effects

Justifications of Deception

• The participant is provided with a sufficient explanation of this action as soon as the research is completed.

• The deception does not otherwise psychologically or physically harm potential subjects.

• The dignity of the subjects is maintained.

Confidentiality = Privacy of subjects and nondisclosure of their participation in a research project

Debriefing = Full disclosure to research participants of the true nature and purpose of a research project after its completion

Research with Animal Subjects

• Must be humane and worthwhile

• Must be done in order to help humans

Understanding Research Results

Descriptive Statistics = mathematical procedures for organizing collections of data

Inferential Statistics = mathematical procedures for determining whether relations or differenced between samples are statistically significant

Descriptive Statistics

(1) Measures of central tendency = a statistical measure used to characterize the value of items in a sample of numbers (mean & median)

(2) Measures of variability = a statistical measure used to characterize the dispersion in values of items in a sample of numbers (range & standard deviation)

Descriptive Statistics (cont.)

(3) Measurement of Relations = used in correlational studies to measure the degree to which two variables are related (scatterplot & correlation coefficient)

Inferential Statistics

Statistical significance = the likelihood that an observed relation or difference between two variables is not due to chance factors

• If there is a large difference between 2 groups, then the IV had a significant effect.

• If there is a small difference between 2 groups, then it is due to chance.

THE END