Types of Experiments Flashcards
What are experimental methods?
An attempt to find a cause & effect relationship between the IV and DV, and to measure the extent of this effect.
What are the 4 types of experiments?
Laboratory
Field
Natural
Quasi
What is a lab experiment?
Conducted in controlled conditions.
Researcher manipulates IV to measure effect on DV.
What are the strengths of a lab experiment?
= High Internal Validity =
EVs can be controlled - prevents them becoming confounding variables which negatively affect DV - cause & effect can be established.
What are the weaknesses of lab experiment?
= Lacks external validity =
Artificial environment - lacks ecological validity & unnatural behaviour (since ppl know) - cannot be generalised to everyday life since it lacks mundane realism
What is a quasi experiment?
An experiment where the IV can’t be manipulated and randomly allocated to groups because it’s a personal characteristic of the participants.
OFTEN conducted in a natural setting but sometimes are in a lab setting.
Researcher cannot randomly allocate the participants to groups.
The IV is a difference between people,
(E.G. gender, age, personality)
Quasi means ‘almost’ in Latin
What are the weaknesses of a quasi experiment?
= Cannot be randomly allocated & Confounding =
Pps can’t be randomly allocated to groups - uncontrolled participant variables might act as confounding variables - reduces the internal validity of the study - less certain that IV alone caused effect on DV - makes it harder to establish cause & effect.
CAN relate to evaluations of lab/natural experiments.
What are the strengths of a quasi experiment?
= Can compare different types of people =
Can compare easily - provides insight into similarities / differences between groups of ppl.
= Personal characteristics =
Can investigate effect of personal characteristics on behaviour.
What are the strengths of field experiments?
= High level of ecological validity =
Setting is more natural - results likely to be representative of normal behaviour in everyday life.
What are field experiments?
Conducted in natural conditions.
Researcher manipulated IV to measure effect on DV.
What are the weaknesses of field experiments?
= Less control over EVs =
Natural setting means less control over EVs - can become confounding variables and affect findings - cause & effect relationship can’t be established as other factors may’ve impacted DV, other than IV.
= Ethical issues =
Ppl unaware they’re part of investigation - cannot give informed consent - cost-benefit analysis needed to tell if outcomes will outweigh costs.
What is a natural experiment?
Conducted in a natural or lab setting.
Researcher DOES NOT manipulate the IV as it is naturally occurring.
IV is an event that has already happened.
What are the strengths of a natural experiment?
= High external validity =
Because of naturally occurring IV - high ecological validity - relates to real world situations.
= Unique Insight =
Gained into real-life situations - can study IVs that cannot usually happen for ethical or impractical reasons in a lab or field exp.
What are the weaknesses of natural experiments?
= No control over EVs =
Researcher can’t control situation or EVs - difficult to establish cause & effect relationship - confounding variable may’ve affected result instead of IV - internal validity decreases.
= Interesting naturally occurring events may occur rarely =
Limits the opportunity to generalise results to other similar events.
