Sampling Flashcards
target population
the population we would like to generalize our findings too
accessible population
portion of population we have access too
a lot of inclusion criteria creates _______
high internal validity, low external validity
probabilistic sampling is _______________
truly random sampling
simple random sampling
use random number generator to pick a certain number of particiapants from accessible population
systematic sampling
divide number wanted by accessible population and pick that number participant. ex: want 40, have 400 eligible, 40/400 =10. use every 10th patient.
stratified random sampling
use random sampling to get people from different categories. Ex. 25 people from each income bracket represented.
disproportional sampling
use weighing factor to make sure that smaller and larger populations are equally represented
cluster or multistage sampling
successive random sampling. Ex. randomly pick state, randomly pick county, randomly pick hospital, randomly pick patients.
non-probabilistic sampling is _______
not truly random
convenience sampling is____
broken into convenience sampling (recruit every patient as they are admitted) or volunteers from fliers
quota sampling
example: you want 100 participants total. You have income data and find that 50% of participants fall in middle, 10% from top portion, 40% from bottom. Sample will be made up of 50% from middle, 10% from top, and 40% from bottom bracket.
purposive sampling
very crappy - researchers interview potential participants to see if they are willing able to do this before including them. Subject to bias
snowball sampling
start with small sample, ask them to refer others with same condition. used for small or rare groups that are hard to identify or locate
