Sampling

Question 1

Opportunity Sampling

Answer 1

Taking the people available at the time

Question 2

Volunteer Sampling

Answer 2

Taking the people who have volunteered

Question 3

Random Sampling

Answer 3

Taking a sample of the population with no bias

Question 4

Stratified Sampling

Answer 4

Taking members of the population in an unbiased way but guaranteed to be representative in certain ways
e.g. a certain strata of boys & girls, then filling these stratas randomly

Question 5

Random Sample eval.

Answer 5

Pros
Unbiased, all population have equal chance of selection. Not all may agree to ppt however

Cons
Not always random as some may not agree to take part

Question 6

Stratified sample eval.

Answer 6

Pros
All subgroups are represented in proportion to the numbers in the population
Specific groups can be chosen according to the variables considered to be important by the experimenter - control over extraneous variables

Cons
Decision of which subgroup to use may be biased
Very lengthy to do and ppts. selected may not always agree to take part

Question 7

Volunteer sample eval.

Answer 7

Pros
Ppts. less likely to drop out
Can get specialised groups of students e.g. if looking to study behaviour of medical students it would be better to put an Ad in a med school than stand in the street hoping to find med students

Cons
Volunteers more likely to be highly motivated or more spare time than GP
Maybe more prone to responding to demand characteristics

Question 8

Opportunity Sample eval.

Answer 8

Pros
Most convenient and least time consuming

Cons
Biased as is only taking people from a certain place
Ppts. may refuse to take part, so has weaknesses of volunteer sample like being more responsiveness to demand characteristics