Involves manipulation of variables to determine cause and effect, participants randomly allocated, all procedures standardised, so the same for all participants
Uses different participants in each of the experimental conditions so each participant only does 1 condition (experimental/control), different participants are tested against each other
No order effect, as different participants so no effect whereby order in which conditions are done may affect outcome
Each participant tested in all conditions of an experiment, participants are tested against themselves
Because the same people are being measured in both conditions there's no individual differences between groups which may have caused a difference otherwise
Order effects, with RMD participants do all conditions and order in which they do these conditions can affect the results, participants may perform worse in 2nd condition due to fatigue/boredom
Chance of Demand Characteristics as if they participate in all conditions more likely they may guess the purpose of study and act a certain way due to this
Different but similar participants are used in each condition, participants are matched on characteristics important for particular study
Order effects are less likely
Participants aren't able to be matched exactly, even if identical twins are used there will be some difference between them, so individual differences remain
Matching participants may be time consuming and expensive, especially if pre-test is required, less economical than most other designs
Researchers generally don't have means to test whole population so sampling is used, part of the population, who are ideally representative of population it was taken from
Each member of population has equal chance of being selected, one way is place all names in container and pick the amount needed, another way is list of all members of population obtained, all names on list are assigned a number, sample generated through lottery method
Unbiased selection, increases the chances of getting an unbiased and representative sample
Generalisability, because the sample should be fairly representative results will be generalisable to the target population
Unrepresentative, just because selection is unbiased it doesn't guarantee an unbiased selection as all females and no males could be selected through this method
Involves taking every nth person from list to create a sample, involves calculating the size of the population and the assessing what size the sample needs to be to work out sampling interval
Involves dividing population into characteristics important for research e.g. age, class etc then the population is randomly sampled within each category
Researchers assess and act on ethical considerations involved in a research before it's conducted, main consideration: health and dignity of participants is protected
Investigators should give participants sufficient details of investigation so they can decide if they want to participate, parental consent should be obtained if child is under 16, can't get informed consent from those under influence of alcohol, drugs or if they're mentally unfit to give consent
Withholding of information or misleading participants is unacceptable if participants are likely to object once debriefed, participants shouldn't be deliberately misled without scientific or medical justification, can't gain informed consent if deception occurs, if deception is used, participants must be told immediately afterwards and given opportunity to withhold their data from study
Group receiving the placebo sets the baseline and is there to act as a purpose of comparison, if a change in behaviour of experimental group is greater than that of the control group, researcher is able to conclude cause and effect was the IV
Research involves interaction between participant and researcher, the interactions can affect findings, several features of research studies that enable participants to guess what study is about, this can cause demand characteristics like please-u, screw you effect, acting unnaturally due to nervousness, fear of evaluation or social desirability bias