Sampling

Question 1

Opportunity - Recruiting who is convenient

Answer 1

Advantage - Using first suitable P’s so saves time

Disadvantage - Biased sample as will only get certain types of people e.g. people midday on weekday unlikely to be professionals as they’re working

Question 2

Random - Gather P’s using random methods e.g. name generator

Answer 2

Advantage - Unbiased, all P’s have equal chance of selection

Disadvantage - Time consuming to make list of all possible P’s e.g. everyone in school year

Question 3

Systematic - Gather P’s using Nth term e.g. every 10th person on register

Answer 3

Advantage - Objective system so unbiased

Disadvantage - Not truly biased unless start with random P using random method and then select Nth term after

Question 4

Stratified - Identify proportional subgroups within target population

Answer 4

Advantage - Representative as proportional representation of subgroups

Disadvantage - Time consuming to identify subgroups e.g. proportion of different ethnicities in a year group

Question 5

Self select - Gather P’s using advertisement for them to select themselves e.g. poster, newspaper

Answer 5

Advantage - Access to variety of P’s e.g. everyone who reads certain newspaper, may be less biased

Disadvantage - Volunteer bias as P’s likely to be certain type of person e.g. highly motivated, outgoing etc…

Question 6

Snowball - Current P’s recruit others, who then further recruit

Answer 6

Advantage - Access groups of people difficult to reach e.g. drug addicts

Disadvantage - Not a good cross section of target pop as it’s recruiting friends of friends, so bias as may all be similar etc…

Question 7

Key word: Target Population

Answer 7

Group of people researcher interested in, sample selected from these and generalisations made about them.

Question 8

Keyword: Sampling Frame

Answer 8

Smaller group within target population to draw sample from.

If target pop is ‘babies in the UK’ the sampling frame may be two hospitals in London