PSYCHOLOGY CHAPTER 2
PSYCHOLOGICAL RESEARCH METHODS
Lesson 1
What Is Research?
Approaches to Research
Researchers must begin with a specific question about a limited hypothesis.
They also need a sample that is representative of the population to achieve external validity.
External validity means the results can be applied to the larger population.
Psychologists can use random or stratified sampling to get a representative sample.
6 TYPES OF RESEARCH
NATURALISTIC OBSERVATION
CASE STUDY
SURVEY
LONGITUDENAL STUDY
CROSS-SECTIONAL STUDY
EXPERIMENT
ADVANTAGES/DISADVANTAGES OF EACH
Research Methods
Studies can be:
Qualitative
focusing in-depth on a limited number of subjects
Quantitative
examining a large population for a limited purpose.
Case studies, naturalistic observation, surveys, and experiments
are all ways to collect data to analyze.
Correlations describe how two sets of data relate to each other
correlations can be positive or negative.
Experiments allow psychologists to control variables that can unknowingly influence results.
Today, ethics committees must approve experiments before they are conducted, and safeguards
are in place to protect animals used in research. This was not always so.
Lesson 2
Problems and Solutions in Research
Avoiding a Self-Fulfilling Prophecy
Psychologists must avoid self-fulfilling prophecies
their expectations cannot be known to subjects being tested.
In a single-blind experiment, the participants do not know if they received an active treatment
or placebo, but the researcher does.
In a double-blind experiment, neither the participants nor the researchers know who received
treatment.
The placebo effect is a change in a patient’s physical state that results solely from the patient’s
knowledge and perception of treatment.
The Milgram Experiment
Stanley Milgram conducted a controversial experiment to determine the influence of authority.
Participants believed they were administering painful shocks to others at the command of the
researcher.
Milgram’s experiment is considered a single-blind study because participants were unaware of
the fact that they were not actually administering shocks.
http://www.youtube.com/watch?v=pdb20gcc_Ns
Lesson 3
Statistical Evaluation
Descriptive Statistics
Statistics is a branch of mathematics used to organize data into meaningful information.
Descriptive statistics uses graphs, charts, tables, and percentages to organize data.
Frequency distribution tells how often a score or observation occurs.
Researchers look for the central tendency using the mean, the mode, or the median.
Standard deviation, variance, and range tell how data are distributed.
The correlation coefficient explains the relationship and its strength between two sets of data.
Inferential Statistics
Inferential statistics uses math to determine whether data support hypotheses or are the result
of chance.
If results from research are statistically significant, then they are very likely not the result of
chance.