EXPERIMENTS

What is the aim of an experiment?

To establish a cause-and-effect relationship by manipulating an independent variable and measuring its impact on a dependent variable

Features of an experiment (AO1s)

• Has a hypothesis

• Has an IV that is manipulated & a DV that is measured

• EV are controlled by standardised procedures + operationalization of variables

• Has different conditions (experimental/control)

• Has a design (repeated measures, etc)

• Can be done as a true, lab, field, quasi or natural experiment

Strengths of an experiment (AO3s)

• RELIABILITY; designs/procedures easy to replicate

• APPLICABILITY; useful for understanding behavior + making cause-and-effect relationships

• VALIDITY (INTERNAL); control over EV / confounding variables

Limitations of an experiment (AO3)

• GENERALISABILITY; low EV- artificial setting with highly standardized conditions

• VALIDITY; can be biased because of participant variables, demand characteristics, order effects, researcher / confirmation bias

Kinds of experiments

Lab, field, quasi, natural

Lab experiment

Participants do not need to be randomly allocated to conditions (e.g matched pairs)

True experiment

Participants are randomly allocated to conditions

Quasi experiment

involves a pre-existing group that shares a desired characteristic that is unethical/impossible to manipulate

Natural experiment

the result of a naturally occurring event (pre-existing IV). doesn’t show direct causation but can imply a casual relationship between an IV & DV

Field experiment

Done in a natural setting/the real world, outside of a lab

Kinds of hypotheses

EXPERIMENTAL

• One-tailed/directional; states an event/change and the direction (positive/negative effect)

• Two-tailed/non-directional; states an event/change but not the direction (something will affect something. how? idk)

NULL

• states that one variable will not cause an event/change on the other variable