Sampling Methods

Question 1

Opportunity Sampling

Answer 1

Recruit people most convenient/available to you e.g. people walking past you.
Advantages;
-Easy as you just use the first suitable participant you can find.
-This makes it quick.
Disadvantages;
-Biased=sample is drawn from a small part of the target population = unrepresentative sample = harder to generalise findings.

Question 2

Random Sampling

Answer 2

Lottery Method;
Put names of possible participants in a hat and select the amount needed.
Random Number Generators;
Give each participant a number, Pick random number using generator/calculator.
Advantages;
-Equal chance of being chosen
-Unbiased as everyone has equal chance
Disadvantages;
Need a list of all possible participants which may take time.
May need to replace people, making the sample no longer random.
May end up biased as there is no equal guarantee an equal number of e.g. female;male.

Question 3

Snowball Sampling

Answer 3

Already chosen participants recruit further participants from people they know.
Advantages;
-Reach a wider community.
-Allows researcher to locate groups of people who are difficult to access e.g. drug addicts.
Disadvantages;
-May take time.
-Not a good section from the target population as its friends of friends.

Question 4

Self-select Sampling

Answer 4

Advertise in newspaper/t.v. etc.
Advantages;
-Gives a variety of people the opportunity to apply =more representative and less biased.
Disadvantages;
-Biased as participants are likely to be more highly motivated to be helpful resulting in volunteer bias.

Question 5

Stratified Sampling

Answer 5

Subgroups/strata within a target population are identified. e.g. boys/girls…Age groups etc.
Participants are obtained from each strata in proportion to their occurrence in the target population.
Selection from the strata is done using a random technique.
Advantages;
-More representative than other methods because there is a proportional representation of subgroups.
Disadvantages;
-Very time consuming to identify subgroups.
-May be a biased sample as some of the selected participants may refuse to take part.

Question 6

Quota Sampling

Answer 6

Same as stratified only we don’t randomly select our participants but use another method such as opportunity sampling.
Advantages;
-Sample has a good chance of being representative of the general population because of the rate of occurrence being the same.
Disadvantages;
-Risk of sample being biased as we may only be accessing certain sections for our target population.

Question 7

Systematic Sampling

Answer 7

Select using predetermined system e.g. every 6th,14th, 29th etc from a list.
Advantages;
-Unbiased as participants are selected using an objective system.
Disadvantages;
-Not unbiased/random unless you select a number using random method ant start with this person