Research Sampling Flashcards
research population
a group sharing some common characteristic, (cannot realistically study)
Sample
set of individuals that represent the population (subset)
representative sample
sample with the same characteristics as the population
biased sample
sample with different characteristics from those in the population
selection bias
survey return rate, researchers going door to door
power analysis
resource equation
E= (total nb of animals)-(total number of groups)
E is the degree of freedom of ANOVA
Non-probability sampling
population is not completely known-> difficult to identify size, 2 methods:convenience and quota
convenience sampling
sampling method where participants are easy to access and available to participate
convenience sampling examples
setting up booths, volunteers
quota sampling
identify a subgroup, then choose from each subgroup to get a quota
simple quota sampling
little is known about the characteristics of a population:
brain activity of 20 students taking NEUR course after drinking coffee : 10 in the AM, 10 in the PM
proportionate quota sampling
demographics known and proportionately represented in sample :
brain activity of 20 students taking NEUR course after drinking coffee : CUneuro program: 60% F,40%M - 12M, 8F
probability sampling
must know the exact size of population, based on random sampling
simple random sampling
all individuals have equal chance of being selected, each one independent of the other
simple random sampling with replacement
after each selection, ind. is added back to the pool, can be chosen more than once
simple random sampling without replacement
after selection, ind. is removed from the pool, probability changes w/ each selection
systematic sampling
sampling method where you choos every n^th (ex: every 4th participant) , more representative sample
stratified random sampling
population is divided into strata (subgroup) then participants selected from each strata.
proportionate stratified sampling
select different proportion (%) from each strata, depends on what representation in actual pop. , difficult to compare between strata if some are smaller % of pop.
Cluster sampling
sampling method where pop. can be identified into clusters then choose from a proportion of the clusters