Types of experiments

• Lab experiment

  Conducted in a highly controlled environment
• Field experiment

  Takes place in a natural setting where the researcher goes to the pps usual environment instead of a lab
• Natural experiment

  Conducted in a natural setting where the IV is not manipulated since they occur naturally
• Quasi experiment

  Naturally occurring IV - difference between people that already exist (e.g. Age) and the researcher examines the effect of this difference on the dv
• Which experiments have the IV manipulated by the researcher

  Lab and Field
• Which experiments had natural IVs that the researcher does not control

  Natural and quasi
• Lab advantages:

  High internal validity (certain cause and effect due to high control over EV and CV)

  Better replication chance due to high control
• Lab disadvantage:

  Low mundane realism - tasks in labs are unrealistic to real life

  Low external validity - experiments may lack generalisabilty because may behave in unusual ways

  Unnatural behaviour because people are aware that they are being tested
• Field advatages:

  Higher mundane realism than lab - more natural environment

  Less bias from sampling

  Higher external validity - May produce more valid and authentic behaviour

  Greater ecological validity - high generalisability
• Field disadvantage:

  Important ethical issues

  More bias from extraneous variables

  Invasion of privacy as pps cannot consent to being studied

  Difficult to record data accurately

  Loss of control of EV and CV = cause and effect are harder to establish, replication not possible
• Natural advantage:

  Provide opportunities for research - allows "real" problem studies

  High external validity since they involve the study of real world issues

  Very little bias
• Natural disadvantage:

  Naturally occurring events rarely happen - reduces research opportunities

  Participants may not be allocated randomly - lacks realism

  Only where conditions occur naturally
• Quasi advantage:

  Carried under controlled conditions - better repeatability

  Allows for comparison between types of people
• Quasi disadvantage:

  Cannot randomly allocate pps to conditions - leads to confounding variables

  IV is not deliberately changed thus IV cannot claim IV is not caused by observable change

  Low internal validity because pps may be aware of experiments