STUFF I NEED TO KNOW Flashcards
What is simple random sampling?
subjects are selected at random from a list of the whole population. Every possible sample of the required size is equally likely to be selected
What is stratified sampling?
the population is divided into subgroups or strata, a random sample is taken from each of them.
(in a proportional stratified sample, the number of subjects chosen from each stratum is proportional to its size)
What is cluster sampling?
the sample is chosen from a number of subgroups, known as clusters.
What is systematic sampling?
can be used when there is a ordered list of the population. Each individual on the list is numbered, and items are selected at equal intervals (eg. every 10th). the starting points are often chosen at random
What is opportunity sampling?
the sample is selected from a source that happens to be easily avaliable
What is quota sampling?
each person collecting the data is required to choose certain numbers of subjects from particular groups
(eg. 30 men, 30 women, 40 teenagers)
What is self selected sampling?
those involved choose to take part in
What are examples of self-selected sampling?
clinical trials, online surveys, government consultations
What is an advantage of simple random sampling?
every member of the population has an equal chance of being chosen
What is an disadvantage of simple random sampling?
it can be very time consuming and it is usually impractical
What is an advantage of systematic sampling?
you are unlikely to get a biased sample
What is an disadvantage of systematic sampling?
-it is not strictly random, some members of the population cannot be chosen once you have decided where to start on the list
What is an advantage of stratified sampling?
-it is the best way to reflect the population accurately
What is an disadvantage of systematic sampling?
it is time consuming and you have to limit the number of relevant variables to make it practical
