sampling Flashcards
probability sampling
everyone from population have an equal chance of being selected
randomly selectcitng
homogeneous
jednorodny
systematic sampling
we get every xth part o population
stratified random sampling
dividing population into subpopulation and then selecting from each samples (we use proportional sampling from each subpop)
ex. divide to male and female and then into income, place …
sampling error
diffrence betwen the population and the sample
standard error
the measure of precision of a sample means (or sampling error)
SD sample/n^1/2
(standard dev is a measure of dispersion)
entail
wiązac się
cluster sampling
population divided into clusters and then we randomly chose which cluster is a sample (the whole cluster should be a sample - one stage or we sample from a cluster - 2 stage)
the lowest precision but cost and time efficient
convinience sampling
selecting easy to obtain or small cost data
judmental sampling
chosing based on knoledge
sampling
the bigger the sample the less error
standard error/standard dev
error - precision on a sample - will decrese when n will rise
dev - dispersion - constant
resampling
we dont know the pop but we know the sample
making a population from a sample.
bootstrap
computer generated resample
jackknife methon
we can only gain n resamples
