Experimental Methods Flashcards
What are the four types of experimental methods?
-Laboratory
-Field
-Natural
-Quasi
what is a laboratory experiment?
-experiment carried out in a controlled setting, allowing researcher to exert a high-level of control over the IV and eliminate control for cofounding variables
-IV manipulated to observe effect on DV, highly controlled
What are strengths of laboratory experiments?
-Control over variables shows causing effect to be established (IV caused by DV)
-Replicability as possible, which means reliability can be established (control)
what are limitations of laboratory experiments?
-artificial conditions make it difficult to generalise other settings, lacks ecological validity (caused by control, due to task)
-Demand characteristics can occur as participants respond to cues of the aim experiment
What is a field experiment?
-an experiment carried out in the natural environment of the individuals being studied
-IV- directly manipulated by experimental to observe effect on DV.
-The participant may not know that they are being studied
-Some control
What are the strengths of field experiments?
-improved ecological validity because pp’s are unaware they are taking part and in a natural environment
-Reduction of demand characteristics Because the participants are unaware they are taking part in an experiment
What are the limitations of field experiments?
-less control of extraneous variables
-More time-consuming, as you need to wait for environmental conditions
What is a natural experiment?
-IV isn’t directly manipulated
-IV occurs naturally
-allocation of participants not controlled by experimenter
what are strengths of a natural experiment?
-Reduction in demand characteristics
-high ecological validity due to lack of direct intervention
what are limitations of natural experiments?
-inevitable many extraneous variables because of a lack of control
-replication is impossible due to rarity of the situation
what is a quasi experiment?
-has an IV that is based on existing difference between people (predetermined characteristics- planned)
-No one has manipulated this difference, it simply exists
What are strength of quasi experiments?
-often carefully planned, which makes it replicable
-useful to make comparison between types of people where it is impossible or impractical to manipulate variables
What are limitations of quasi-experiments?
-Can’t randomly allocate participants to conditions, and therefore there may be confounding variables, which means we cannot establish causality
-Often carried out in a laboratory, and therefore may be demand characteristics
What is an example of a lab experiment?
Asch’s variations
what is an example of a field experiment?
bickman
What is an example of a natural experiment?
Romanian orphans
How can the reliability of experiments be improved?
-when possible take more than one measurement from each ppt and take a mean score- reduces the impact of any anomalous score
-pilot study can be used to check the proposed method measurements works properly and that ppt’s can use any apparatus successfully
How can the external validity of an experiment be improved?
-Ecological Validity- by conducting the experiment in a more naturalistic, real life setting e.g. a field experiment
-Population Validity- take larger sample, more varied sample, e.g. wider age group or geographical area
