Four research goals: describe, predict, control, explain.

Five steps: theory → hypothesis → test with a method → analyse data → share and repeat (replication).

Method	What it does	Weak point
Descriptive (case study, observation, self-report)	describes what is happening	can be one-sided; hard to use for everyone
Correlational	shows if two things are connected	no cause and effect (directionality problem + third variable problem)
Experimental	can show cause and effect	needs careful control

In an experiment: the researcher changes the independent variable and measures the dependent variable. The control group gets no treatment; the experimental group gets the treatment. Random sample chooses people by chance; random assignment puts them into groups by chance.