Ch.5 Flashcards
Sample
The process of drawing a number of individual cases from larger population
Why do we need to sample ?
Because studying every single instance is impractical or too expensive.
When would it be unnecessary to sample?
When the number of things we want to examine is small , when data are easily accessible and when data quality is unaffected but the number of things we look at.
Element
A kind of thing a researcher wants to sample
Population
The group of elements from which a researcher samples and to which she or he might like to generalize
Sample
A number of individual cases drawn from a larger population
Sampling frame or study population
The group of elements from which a sample is actually selected
Non probability samples
Samples that have been drawn in a way that doesn’t give every member of the population a known chance of being selected
Probability samples
Samples drawn in a way to give every member of the population a known (nonzero) chance of inclusion
Biased samples
Samples that are unrepresentative of the population from which they been drawn
Generalizability
The ability to apply the results of a study to groups or situations beyond those actually studied
Coverage error
An error that results from different between the sampling frame and the target popular
No response error
An error that results from differences between non responses and responders in a survey
Sampling error
Any difference between sample characteristics and the equivalent characteristics in the sampling frame when this difference is not due to non response error.
Parameter
A summary of variable characteristics in a population