Psych Research Methods

Scientific method

observations, theories, hypotheses

Research designs

Experimental and correlational

Peer review

research reported in scientific journals is screened, critiqued, and improved by scientists in the field/area

Science must be…

empirical and objective

 Systematic collection and analysis of data

 Formal observation and measurement

 Free from scientists’ personal emotions

and biases

Theory

explains or predicts behaviors and/or relationships (ex: sleep affects memory)

Hypothesis

Specific and falsifiable prediction about relationship between variables

 Variable = attribute or behavior that can assume different values

Operational

precise statement of how a variable is measured in a study

Variables:

 Sleep, classroom learning – how do we operationally define these?

Reseach design

method used to collect, analyze, and interpret data

Correlational

invetigate relations between variables

Experimental

investigate cause and effect

Random sampling

Ensures that every member of a population has an equal chance of being included in the sample

Nonrandom sampling

Most research participants are college

students in the United States

Correlational research

Measure 2 or more variables

 Assess relationship

 Correlation does NOT equal causation!

Positive correlation

variables both increase or decrease

Negative correlation

one variable increases and the other decreases

r (correlation coefficient)

ranges from -1.00 to +1.00

Positive correlation ex

Hours of studying and exam scores

Negative correlation ex

Quality of health and stress level

Third variable

affects both measured variables

Experimental research

used for determining whether there is a causal relationship between variables

Random assignment

a procedure that assigns participants to a condition/group chance

• want groups to be as similar as possible

• IV = only difference (hopefully)

IV

variable that is changed, manipulated, or selected by a researcher to measure its effect, representing the “cause” in a study

DV

the factor being measure or observed, representing the “effect” or outcome that changes based on the IV