Opportunity Sample: Consists of taking the sample from people who are available at the time the study is carried out and fit the criteria your are looking for.
Random Sampling: When every member of the population has an equal chance of being chosen.
Self-Selected Sample :(or volunteer sampling) consists of participants becoming part of a study because they volunteer when asked or in response to an advert.
Snowball Sample: Can be used if your population is not easy to contact.
Strengths and weaknesses of sampling method
Strengths: Quick & easy to select the sample as you simply take advantage of the people that are around. No need to select people because of predetermined catergories for characteristics. Weaknesses: May be biased as unlikely to be representative of a target population.
Strengths: Identifying everyone in the target population and then selecting the number of participants needed. Weaknesses: 1)Time consuming. 2) Often impossible to carry out when you have a large target population.
Strengths: 1) Useful as it's quick and relatvely easy to do. 2) Can also reach a wide variety of participants. Weaknesses: Type of participants who volunteer may not be large representative the target population.
Strengths:Process is cheap,simple and cost efficient. Technique needs little planning amd fewer workforce. Weaknesses: 1) Representatives of the sample is not guaranteed. 2) Researcher has little control over the samling method.
Withdrawal from the investigation
Protection of participants