Types of Experiment

3.2.3 Research Methods

laboratory experiment

laboratory experiment

the researcher manipulates the IV in a controlled environment, using standardised procedure

field experiment

the researcher manipulates the IV in a real-world setting

natural experiment

the researcher does not manipulate the IV; change is caused by something or someone else

quasi experiment

the IV occurs naturally and cannot be changed (e.g, age or gender)

strengths of laboratory experiments

• high internal validity

• experiment can be repeated

• EVs can be controlled

weaknesses of laboratory experiments

• lacks generalisability

• low external validity

• demand characteristics may be present

• low mundane realism

strengths of field experiments

• high mundane realism due to natural environment

• high ecological validity

weaknesses of field experiments

• EVs are more likely

• harder to replicate experiment

strengths of natural experiments

• high ecological validity

• can conduct research that would otherwise be considered unethical

weaknesses of natural experiments

• lacks generalisability due to small sample size

• cannot randomly allocate participants

• low internal validity (difficult to prove IV cause the change in DV)

strengths of quasi experiments

• can be conducted in labs » DV can easily be measured

• replicable

weaknesses of quasi experiments

• cannot randomly allocate participants

• low internal validity (difficult to prove IV cause the change in DV)

reasons why placebos are unethical

• participants believe they are receiving treatment, but are not

• could deprive participants of effective treatment, potentially causing harm

• violates ethical guidelines from BPS