sampling

Question 1

Define population

Answer 1

The group of individuals a researcher is interested in and about whom generalisations can be made.

Question 2

Define sample

Answer 2

A smaller group of the population; representative so that generalisations about the population can be made.

Question 3

Name the sampling methods

Answer 3

Volunteer sample
Opportunity sample
Random sample
Stratified sample
Systematic sample

Question 4

Opportunity sampling

Answer 4

A sample produced by selecting people who are most easily available at the time of the study.

Question 5

Strength of opportunity sampling

Answer 5

The easiest method; you use first suitable participants you can find. Therefore, is less time consuming.

Question 6

Limitation of opportunity sampling

Answer 6

Inevitably biased; sample is drawn from a small part of the population.

Question 7

Random sampling

Answer 7

A sample produced by using a random technique such that every member of the target population being tested has an equal chance of being selected.

Question 8

Name random techniques

Answer 8

Random number generators
The lottery method

Question 9

The lottery method

Answer 9

Drawing numbers or names out of a hat.

1. Obtain a list of all the people in the population.
2. Put all the names in a lottery barrel or hat.
3. Select the number of names required.

Question 10

Strength of random sampling

Answer 10

Unbiased; all members of the target population have an equal chance of selection.

Question 11

Limitation of random sampling

Answer 11

Time consuming; need to have a list of all the members of the population and then contact all of those selected.

Question 12

Stratified sampling

Answer 12

A sample produced by identifying strata (subgroups) according to their frequency in the population. Participants are then selected randomly from the strata.

Question 13

Strength of stratified sampling

Answer 13

More representative; a proportional and randomly selected representation of strata.

Question 14

Weakness of stratified sampling

Answer 14

Very time consuming to identify subgroups then randomly select participants and contact them.

Question 15

Systematic sampling

Answer 15

A sample produced by using a predetermined system to select participants; obtained by selecting every nth person.

Question 16

Strength of systematic sampling

Answer 16

Unbiased as participants are selected using an objective system.

Question 17

Limitation of systematic sampling

Answer 17

Not truly unbiased/random unless you select a number using a random method and start with this person, and then select every nth person.

Question 18

Define volunteer sample

Answer 18

A sample that relies on volunteers solely.

Question 19

Strengths of volunteer sampling

Answer 19

More representative; Gives access to a variety of participants.

Question 20

Limitation of volunteer sampling

Answer 20

Volunteer bias; participants have special characteristics and are likely to be more highly motivated to be helpful, or more broke and needing the money offered for participation.