Research 3
convenience sampling
a group of elements that are readily accessible to the researcher
element
a kind of thing a researcher wants to sample
quota sampling
a nonprobability sampling procedure that involves describing target population in terms of what are thought to be relevant criteria and then selecting sample elements to represent the "relevant" subgroups in proportion to their presence in the target population, similar to stratified sampling
purposive sampling
a nonprobability sampling procedure that involves selecting elements based on the researcher's judgement about which elements will facilitate his or her investigation, when you need to know about a particular group
snowball sampling
a nonprobability sampling procedure that involves using members of the group of interest to identify other members of the group, good for when you have a hard to reach population
sample
a number of individual cases drawn from a larger population, who ends up being in your study
simple random sample
a probability sample in which every member of a study population has been given an equal chance of selection, the easiest and fastest
stratified sampling
a probability sampling procedure that involves dividing the population in groups defined by the presence of certain characteristics and then random sampling from each group
cluster sampling
a probability sampling procedure that involves randomly selecting clusters of elements from a population and subsequently selecting every element in each selected cluster for inclusion in the sample, used when data collection involves visits to sites that are far apart
systematic sampling
a probability sampling procedure that involves selecting every nth element from a list of population elements, after the first element has been randomly selected
multistage sampling
a probability sampling procedure that involves several stages, such as randomly selecting clusters from a population, then randomly selecting elements from each of the clusters
margin of error
a suggestion of how far away the actual population parameter is likely to be from the statistic
parameter
a summary of a variable characteristic in a population
statistic
a summary of a variable in a sample
coverage error
an error that results from differences between the sampling frame and the target population ex. the FDR election
nonresponse error
an error that results from people not responding
sampling error
any difference between sample characteristics and the equivalent characteristics in the sampling frame, when this difference is not due to nonresponse error
population
everyone that you want to generalize
probability samples
samples drawn in a way to give every member of the population a known chance of inclusion
biased samples
samples that are unrepresentative of the population from which they've been drawn
nonprobablilty samples
samples that have ben drawn in a way that doesn't give every member of the population a known chance of being selected
generalizability
the ability to apply the results of a study to groups or situations beyond those actually studied
selection interval
the distance between the element selected in a sample (N/n)
sampling distribution
the distribution of a sample statistic computed from many samples
sampling frame
the group of elements from which a sample is actually selected, ideally a list of everyone in the population
target population
the population of theoretical interest
sampling
the process of drawing a number of individual cases from a larger population
sampling variability
the variability in a sample statistics that can occur when different samples are drawn from the same population