Psychological Research Methods

• Empiricism states that the best way to understand the world involves direct observation.
• The systematic collection and evaluation of evidence to test beliefs has only emerged in the past few centuries.
• Observation necessitates a method.

The Scientific Method

• Involves developing a theory that leads to a falsifiable hypothesis.
• Observations are made to test the hypothesis.
• These tests can disprove a theory but cannot definitively prove it.
• Psychology methods are unique due to the complexity, variability, and reactivity of human beings.

Methods of Observation

• Focuses on discovering what people do.
• Measurement requires defining a property in measurable terms.
• Requires using a device that can detect that property.
• A good definition has construct validity, meaning the measurement adequately characterizes the property.
• A good detector has power, so it can tell when properties are different.
• A good detector has reliability, so it can tell when properties are the same.
• Demand characteristics are aspects of an observational setting that cause people to behave as they think they should.
• Psychologists minimize demand characteristics by observing people in natural habitats or by concealing their expectations.
• Observer bias involves observers' expectations influencing what they believe they observed and what actually happened.
• Psychologists prevent observer bias by using double-blind studies.
• Psychologists typically measure samples rather than entire populations.
• Measurements are visually represented using a frequency distribution.
• Measurements are often of a normal distribution shape.
• Measurements are described using descriptive statistics.
• Central tendency descriptions include the mean, median, and mode.
• Variability descriptions include the range and standard deviation.

Methods of Explanation

• Focuses on discovering why people do what they do.
• Determining a causal relationship between two variables requires establishing a relationship between them.
• Establishing a relationship can be achieved through repeated measurements of each variable and comparing the patterns of variation.
• Synchronized patterns indicate correlated variables.
• Correlations enable the prediction of one variable's value from another's.
• The correlation coefficient (r) measures the direction and strength of a correlation.
• Correlation between two variables doesn't confirm causation due to potential "third variables."
• Experiments address the third-variable problem by manipulating an independent variable.
• Random assignment of participants to conditions created by the manipulation is required.
• Then measuring a dependent variable is required.
• Measurements are compared across conditions.
• If results have a low probability (e.g., 5%) of occurring by chance, differences are attributed to the manipulation.
• An internally valid experiment establishes the likelihood of a causal relationship between variables as defined among participants studied.
• An experiment mimics the real world when is externally valid.
• Psychology experiments primarily test hypotheses derived from theories instead of attempting to mimic the real world.
• Random sampling allows researchers to generalize from samples to populations.
• Random sampling is often not feasible in psychology studies.
• Replication increases confidence, as we can never be absolutely certain that a result is valid.
• Replication involves reproducing results using the original study's procedures and population sampling.
• The replication rate in psychological science is not expected or desired to be 100% due to balancing Type I and Type II errors.

Thinking Critically About Evidence

• People tend to see what they expect, want, and what is present rather than absent.
• Critical thinkers consider disconfirming evidence and absent evidence.
• Science actively identifies and corrects its biases and errors.

The Ethics of Science

• Research ethics boards (REBs) protect the rights of research participants based on respect for persons, concern for welfare, and justice.
• Psychologists must obtain informed consent, avoid coercion, protect participants from harm, balance risks and benefits, avoid deception, and maintain confidentiality.
• Psychologists must respect and treat animals humanely.
• Most people support using animals in scientific research.
• Psychologists must be truthful, share credit appropriately, and provide data access.

A summary of psychological research, focusing on empiricism and the scientific method. It also considers the unique challenges psychologists face due to the complexity of human behavior. Also discussed are methods of observation, measurement, construct validity, power and reliability.