Research Methods Experimental Flashcards
volunteer sampling strengths and weaknesses
strength = quick and easy for researcher - no researcher bias unless they choose where its advertised
weakness = not always representative ( volunteer bias ) - time consuming if no one volunteers
random sampling strengths and weaknesses
strength = not time consuming if small sample - representative if large sample - removes researcher bias
weakness = can be time consuming if large sample
systematic sampling strengths and weaknesses
strength = no researcher bias unless they pick the rule
weakness = might not be representative if small sample - can be time consuming if big sample
stratified sampling strengths and weaknesses
strength = subgroups are proportionally represented - no researcher bias
weakness = time consuming
opportunity sampling strengths and weaknesses
strength = not time consuming
weakness = not representative - researcher bias if they choose where to find the sample
lab experiment definition
highly controlled experiments where the researcher has full control over where and how the research will be conducted - researcher directly manipulates IV and precisely measures DV
field experiment definition
researcher still attempts to hold all variables constant while isolating and manipulating IV and measuring effect on DV and the research is conducted in a natural environment
natural experiment definition
conducted in p’s natural environment and IV is naturally occurring - researcher is unable to control EV’s
quasi experiment definition
the IV is within a person e.g gender, age or schizophrenia and is not manipulated by researcher - its naturally occurring but concerning a person
lab experiment strengths
-high in internal validity as researcher has high control over EV’s and directly manipulates IV which establishes cause and effect
-highly replicable as high degree of control means the experiment can be repeated and same results will be found so high in reliability
lab experiment weaknesses
-low in ecological validity as conducted in artificial environments so doesnt represent the real world
-may be influenced by demand characteristics as its in an artificial environment and are often aware they’re being studied so may change their behaviour not representing their natural actions so lacks validity
field experiment strengths
-fair degree of internal validity as researcher attempts to control EV’s and isolates IV to allow direct manipulation so change in DV is most likely a result of change in IV
-less likely to be influenced by demand characteristics as the experiment is conducted in their natural environment so p’s will act natural so high in ecological validity
field experiment weaknesses
-ethical issues as p’s are studied in their natural environment so may not be aware they are being studied so not given the opportunity to provide informed consent
-lower in internal validity compared to lab experiments as although researcher attempts to control EV’s they’re unable to do this as well as in a lab experiment so can’t be as confident in establishing causality
natural experiment strengths
-high in ecological validity as research is in a natural setting and IV is naturally occurring so p’s are less likely to change behaviour and show demand characteristics
-useful in investigating concepts that would be unethical to directly manipulate as researcher doesnt manipulate IV so doesnt break the ethical guideline of protection from harm
natural experiment weaknesses
-low in internal validity as researcher has little to no control over EV’s and the IV isn’t isolated or carefully manipulated so difficult to establish causality
-ethical issues as p’s may be unaware they are being studied so aunt given the opportunity to provide informed consent and may not be willing to participate
investigator effects meaning and how to control
results may be knowingly or unknowingly influenced by the researcher as their expectations may influence how they design a study or how they behave towards p’s which may lead to demand characteristics
ways to control = randomisation, standardised interactions and double blind technique (researcher doesn’t know what group p’s are in)
confounding variable meaning
something that varies systematically with the IV and may act as a second IV
one tailed (directional) and two tailed (non-directional) hypothesis definitions
directional = states there will be a change in the DV and what direction that relationship will go
non-directional = states there will be a change but doesnt state what direction the change will go in