experimental methods

• 4 types of experiments are lab, field, natural and quasi experiments
• a field experiment is carried out in a natural environment and the independent variable is manipulated

  an advantage of field experiments can be that it has high validity as it is carried out in natural environments. Participants may not know they are being studied so this means no demand characteristics

  a disadvantage of field experiments are the ethical issues as if people don't know they are being studied, they haven't given consent. they are also hard to replicate due to the environment
• a lab experiment is conducted in a controlled environment and the independent variable is manipulated

  an advantage of lab experiments can be that they are highly controlled so lowers the risk of extraneous variables. they are more replicable due to the control

  a disadvantage can have lower ecological validity and can not always be generalised to real life. Participants are aware they are being studied so there can be demand characteristics
• a natural experiment is carried out in natural environments and the independent variable is not manipulated

  an advantage of natural experiments is they have high external validity as they involve real life issues or problems that occur

  a disadvantage of natural experiments can be they have no control so extraneous variables can get in the way. They also measure naturally occurring issues so it may be hard to replicate as these issues could only happen once
• a quasi experiment aims to establish the cause and effect relationship, it uses the participants and how they cannot be randomly allocated (for example gender, age)

  an advantage of quasi experiments can be they are done in controlled conditions. they also give an insight to naturally occurring behaviour

  a disadvantage of a quasi experiment can be that the groups can't be randomly allocated
• an experimental design is how participants are allocated to the groups in different conditions of the experiment
• independent groups design: participants are randomly allocated to one of two conditions, one condition is the experimental condition and the other is the control condition
• repeated measures design: participants take part in both conditions of the experiment
• counterbalancing: technique used with repeated measures and is the process of randomly allocating participants to different conditions of an experiment to avoid order effects
• matched pairs design: participants are matched on a variable of interest and then randomly allocated to one of two conditions
• single blind design: participants do not know the conditions of the study, but the researcher does

  deception (ethical issue) lying to the participants
• double blind design: where the participant and researcher don't know which condition the participant is in
• the investigator effect are any cues from the investigator that may influence the participant's behaviour
• inter rater reliability is when there is more than one experimenter and then they agree on the same results
• randomisation limits bias and is based off chance
• standardise experiment is when the researcher keeps everything the same for all participants
• counterbalancing is used with a repeated measures design to avoid order effects (boredom, fatigue).

  counterbalancing is when group 1 do condition A then condition B, and group 2 will do condition B then condition A