Sampling techniques

Question 1

What is opportunity sampling?

Answer 1

The sampling technique most used by psychology students. It consists of taking the sample from people who are available at the time the study is carried out and fit the criteria you are looking for.

Question 2

What is volunteer sampling?

Answer 2

Participants becoming part of a study because they volunteer when asked or in response to an advert (e.g. Poster, online ad…).

Question 3

What is random sampling?

Answer 3

A technique which is defined as a sample in which every member of the population has an equal chance of being chosen. This involves identifying everyone in the target population and them selecting the number of participants you need in a way that gives everyone in the population an equal chance of being picked.

Question 4

What is systematic sampling?

Answer 4

Using a predetermined numerical system to select participants. The numerical interval is applied constantly..

Question 5

What is stratified sampling?

Answer 5

Classifying the population into categories and then choosing a sample which consists of participants from each category in the same proportions as they are in the population.

Question 6

Example of systematic sampling

Answer 6

Every 10th 20th and 30th person from a standard phone directory.

Question 7

Example of stratified sampling

Answer 7

Participants are obtained from each strata in proportion to their occurrence in the general population such as the same proportion of people aged 21-35, 36-50, 51-65 as exists in the general population.

Question 8

Three methods of random sampling

Answer 8

The lottery method (easiest)
Random number table
Random number generators

Question 9

Strength of opportunity sampling

Answer 9

It’s cheap and easy

Question 10

Weakness of opportunity sampling

Answer 10

Drawn from a small part of the target pop so biased. E.g. Using people walking round town on a Monday morning will exclude professional people as they are working.

Question 11

Strength of volunteer sampling

Answer 11

Can be targeted. Get variety in terms of some variables, e,g. Age intelligence occupation

Question 12

Weakness of volunteer sampling

Answer 12

Quite specific types of people such as extraverts so it is biased. This is known as volunteer bias

Question 13

Strength of random sampling

Answer 13

Highly representative sample - everyone has equal chance of being selected

Question 14

Weakness of random sampling

Answer 14

More time-consuming and costly than opportunity and volunteer, and some people may end up refusing to take part if selected

Question 15

Strength of systematic sampling

Answer 15

Unbiased - you’re using an objective system to select participants

Question 16

Weakness of systematic sampling

Answer 16

Periodic traits - the process of selection can interact with a hidden periodic trait within the population. If the sampling technique coincides with the frequency of the trait, the sampling technique is neither random nor representative of the target population. E.g. If every fifth person in a street lives in a flat.

Question 17

Strength of stratified sampling

Answer 17

Likely to be representative because you’re going to the trouble of recruiting the proportions of participants with relevant traits that are seen in the target population.

Question 18

Weakness of stratified sampling

Answer 18

Time consuming therefore costly. People might turn you down when you ask them, you have to employ not only random techniques like generating lists of individuals for the target pop but also finding out and selecting those for your subgroup.