sampling methods Flashcards
what is random sampling
picking pps using a random number generator for example
strengths of random sampling
unbiased all members of population have equal chance of selection
limitations of random sampling
can take time
what is opportunity sample
sample produced by selecting people who are easily available at the time
strengths of opportunity sample
free from researcher bias
limitations of opportunity sample
inevitably biased as sample drawn from small part of population
what is volunteer sample
people who volunteer to take part
strengths of volunteer sample
very easy to set up
limitations of volunteer sample
sample likely to be biased as pps are motivated
what is stratified sample
produced by identifying subgroups in population and creating sample with them according to their frequency in population
strengths of stratified sample
more representative
limitations of stratified sample
very time consuming
what is bias
distorted in some way
what is sample bias
when some members of population are systematically more likely to be selected in a sample than others
what is volunteer bias
idea that people who volunteer to participate in study do not represent the general population
