Sampling Techniques

The process of selecting a representative group of participants for the topic of study.

The target population is the total group from which the sample might be drawn

Opportunity sampling is gaining a group of participants by circumstance - they are there at the time/place. For example, the first 15 people to walk into a classroom.

Pros:

• Practicality - its an easy way to obtain participants, it isnt time consuming and is cost effective. Quick, convinient and economical. It is the most common form of sampling

Cons:

• It is very unrepresentative - it doesnt give a generalisable view of the target population. 
• Researcher bias - researchers tend to use participants who are 'helpful'

Also known as a self-selected sample. This is a group of people that put themselves forward to participate in a study. For example, MIlgram's participants were volunteers.

Pros:

• Practical - convinient, e.g. you advertise a study and wait for participants to apply
• Ethical - the sample volunteer themselves therefore you gain consent

Cons:

• Participant bias - volunteers tend to have a certain personality, e.g. tend to be very helpful. Which doesnt help in trying to find valid results. For example, Milgram's study was seen as having low validity, participants may have only been submissive to him as they felt they were helping him and wanted him to gain the results he was looking for

This works by diving the target population into subcategories, then selecting members in the proporion that they occur within the population. For example, 2.5% of Brits are of Indian origin, so 2.5% of your sample should be of that subcategory (Indian Origin).

Pros:

• Generalisability- the sample is completely representative of the target population.

Cons:

• Practicality - time has to be spent identifying subcategories and calculating proportions

Every member of the target population has an equal chance of being selected, e.g. names out of a hat.

Pros:

• For large samples, it gives the best chance of an unbiased representative sample. 

Cons:

• Practicality - time consuming to list every possibilty for a sample