directional hypothesis
a hypothesis that states the kind of relationship or difference between two variables eg coffee will have an effect on reaction time on ppts
non-directional hypothesis
a hypothesis that predicts that there will be a difference / relationship but does not state the kind of difference eg coffee will change reaction time on ppts
laboratory experiment
an experiment conducted in a controlled situation
validity
testing or measuring what you set out to measure
advantages of an experiment
disadvantage of an experiment
strength of lab experiment
high in internal validity as extraneous variables controlled, so can be confident that any observed change in DV is due to the IV
disadvantages of lab experiment
participants aware = demand characteristics, reducing ecological validity
- IV/DV may be operationalised and so doesn’t represent everyday experiences - so low in mundane realism
- ppts uncomfortable in unnatural environment
field experiment
an experiment conducted in a more natural environment, and participants are usually not aware that they are in an experiment
- IV is still manipulated so casual relationships between IV and DV still demonstrated
field experiment strengths
field experiment weaknesses
natural experiment
IV is not manipulated, instead it is naturally occurring but still a measure of what you expect to see
independent groups design
a ppt only does one experimental condition
repeated measured design
a ppt does both experimental conditions
matched pairs design
ppt matched on any variable of researchers choice eg iq, ethnicity, age, then randomly allocated to one of the two conditions
ABBA effect
RMD strengths
IGD strengths
IGD weaknesses
RMD weaknesses
MPD weaknesses
time consuming and difficult to match all ppt variables as you can only match on variables known to be relevant
- very difficult to match key variables
avoid weaknesses of IGD
avoid weaknesses of MPD
restrict number of variables to match to make things easier
RMD avoid weaknesses
counterbalancing/ABBA