experimental design + types of experiments

repeated measures (design)

same participants in all conditions

controls participant differences but risk of demand characteristics

independent groups(design)

different participants in each condition

avoids demand characterists but risk of participant variable differences

matched pairs(design)

participants paired up based on similar characteristics eg iq scores or baseline memory test

lab experiment

takes place in a controlled or artificial settings

level of control is very high reasearcher control variables tightly

strength:high control over extraneous variables

weakness:low generalisability

field experiment

conducted in a natural everyday setting lower level of control some variables are harder to manage

strengths- realistic behaviour (ecological validity)

weakness- less control

natural experiment

IV changes naturally and researcher doesn’t manipulate low level of control

strengths- allows study of real world events

weakness- lack of control = reduced internal validity

quasi experiment

IV based on pre existing characteristics(age gender) reasearcher can control some aspects

strength- useful for studying variables that can’t be manipulate

weakness- cannot claim full cause and effect

pilot study

a small scale trial of pressures materials and instructions before the main study, to ensure clarity improves reliability and helps identify problems