Types of experiment

• What are the four types of experiment?

  Laboratory, field, natural and quasi
• Laboratory experiments are conducted in controlled environments within which the researcher manipulates the IV and records the effect on the DV, whilst maintaining strict control of extraneous variables. Participants are aware that they are in a study.
• Field experiments take place in a natural setting where the researcher goes to the participants environment. The researcher manipulates the IV and records the effect on the DV. Participants are unaware that they are in a study.
• Natural experiments is where the change in the IV is not controlled by the researcher but would still have happened if the researcher wasn't there. The researcher records the effect on a DV they have decided on. Participants are unaware of the study
• Quasi experiments have an IV based on existing differences between people. No one has manipulated the variable and unlike in a natural experiment the IV cannot be changed. Strictly speaking it's not an experiment. It is naturally occurring and the participant only partakes in one condition. It can occur in a lab or in real life.
• What are the strengths of a laboratory experiment?

  High levels of control over co-founding variables and extraneous variables so the researcher can ensure that any effect on the DV is the result of manipulation of the IV, which means high internal validity
• What are the strengths of a laboratory experiment?

  Replication is more possible due to high level of control and its vital to replicate experiments to see if the results are valid or a one off
• What are the strengths of a field experiment?

  high mundane realism due to natural environment

  Valid and authentic behaviour means high external validity
• What are the strengths of a natural experiment?

  Provides opportunities for research that may not otherwise be undertaken for practical or ethical reasons
• What are the strengths of a natural experiment?

  high external validity as they involve the study of real world issues as they happen
• What are the strengths of a quasi experiment?

  carried out in controlled conditions so they have high levels of control over co-founding variables and extraneous variables (high internal validity) and replication is more possible due to high level of control
• What are the limitations of a laboratory experiment?

  may lack generalisability as a lab is artificial so people may behave differently, which means low external validity

  demand characteristics

  Mundane realism is low
• What are the limitations of a field experiment?

  loss of control over co-founding and extraneous variables so cause and effect between the IV and the DV may be more difficult to establish and precise replication is often not possible
• What are the limitations of a field experiment?

  ethical issues due to the lack of consent and invasion of privacy
• What are the limitations of a natural experiment?

  naturally occurring events are rare, limiting the scope for generalising findings to other situations

  Participants may not be randomly allocated to experimental conditions (only in independent measures) so researchers will be less sure on whether the IV affected the DV

  Could happen in a lab but is affected by demand characteristics and lacks realism
• What are the limitations of a quasi experiment?

  Can't randomly allocate participants to conditions so there may be co-founding variables

  Iv isn't deliberately changed so we can't claim that the IV has caused any observed change
• What type of experimental type is the following:

  A study into train passengers-whether they are more likely to sit in a carriage that has been spotlessly cleaned or one that has been deliberately left unclean

  field
• What type of experiment type is the following:

  comparing the performance on a computerised IQ test with participants who have a) drank an energy drink or b) drank a caffeine free-variety

  Laboratory
• What type of experiment type is the following:

  Comparing the happiness of people living in an area where the government has introduced a smoking ban to their happiness before the ban happened

  natural
• What type of experiment type is the following:

  comparing the aggression of male primates to female primates in a zoo

  quasi