lecture 5 Flashcards
operational definitions:
definitions of variables in terms of the operations needed to produce them
how to define operations?
replication by other researchers and scrutiny by other researchers
extraneous variables (confounders)
have an unintended influence on the results of experiment by changing difference between groups
when an extraneous variable is present. the experiment is:
confounded
nuisance variables:
unwanted variables that can cause the variability within all groups to increase
example of extraneous variable:
giving encouragement and warning to gaming participant
example of nuisance variables:
not holding ruler a precise distance above participants hands
how to control extraneous and nuisance variables:
produce groups that are equivalent prior to the intro of the IV. reduce the effects of nuisance variables as much as possible
randomization:
distributes extraneous variables equally to all groups. eg those who drink cola A regularly and those who regularly drink cola B
elimination:
completely remove the extraneous variable from the experiment. ex test and remove those who are loyal to cola A or cola B, only test those who are undecided so there are no biases
constancy:
keeps an extraneous variable constant. ex only test people who haven’t drank any of their fav cola that day
balancing:
ensures that all participants receive extraneous variable to the same extent. ex if one always prefers the first cola since they’re more thirsty
counterbalancing can control for:
sequence of order effects
lesson of M&M sampling:
sample size really does matter, there is power in. large numbers
we must have a sample that is:
representative of the population we are studying