psych research methods

Variable

any property who values can vary across individuals or over time

Operational definition

A description of a property in concrete measurable terms

Correlational study

Examines the relationship between two variables without manipulating them; cannot prove causation.

Experimental study

Manipulates an independent variable to determine its effect on a dependent variable; can establish cause and effect.

Random assignment

assigning participants randomly to experimental conditions

Random sampling

every person in the population has an equal chance of being selected

Convenience sample

this sample consists of people who are conveniently available for the study

Placebo Effect

When participants' expectations lead

them to experience some change even

though they receive an empty or fake

treatment

Experimenter Bias

The experimenter's expectations influence the

outcome of a study

Demand Characteristics

Participants form an interpretation of the

experiment's purpose and subconsciously

change their behavior to fit that interpretation.

Positive (+) correlation

both variables either

increase or decrease together

Negative (-) correlation

one variable increases

when the other decreases

Zero correlation

one variable is not predictably

related to the other

Correlation Coefficients

A number that measures the strength and direction of the relationship between two variables.

It ranges from -1 to +1

Applied research question

A research question focused on solving a real-world problem or improving people's lives.