Participants choosethemselves to take part in the study, via…
email surveys
singing up or applying to take part
responding to adverts or posters.
What are the strengths of volunteer/self-selected sampling?
Relatively easy as participants come to you
Participants likely to remaincommitted and not drop out (prevents chance of small unrepresentative sample)
can reach a wide variety of participants through advertising
What is systematicsampling ?
A systematic method is chosen for selecting from a target group e.g every fourth person in a list used as a participant. Differs from random sampling as it does not give an equal chance of selection to each individual in target group.
strengths of systematic sampling:
Can provide unbiased sample as researcher has no part in deciding who is selected (less researcher bias, more validity)
more chance of gaining representative sample, varied sample from systematic formula
What is randomsampling?
Every member of the population has a fair and equal chance of taking part