sampling methods

Question 1

simple random

Answer 1

Every unit of the population is equally likely to be sampled.
E.g: Assign every unit of a population a number and use a random no. generator to pick units until you have enough

Question 2

Systematic

Answer 2

Find a sample size (n) from population (N) by choosing one unit from random out of the first ‘k’ units and then every ‘k’th member after that

e.g you want a sample of 20 from a population of 100. 100/20 = 5 so you will pick one of the first five people at random then every 5th person thereafter

Question 3

Stratified

Answer 3

Create distinct groups to be represented by your sample and then split the population into these distinct groups.
The proportion of each group should be the same in your sample as your population.

Question 4

Opportunity

Answer 4

You pick units that you have easy access to until you have enough.

E.g you sample people that are in the study center at the same time as you to find out about 6 form students

Question 5

Quota

Answer 5

A mix of stratified and opportunity. you decide on distinct groups to sample and how many units you want in each group. you then use opportunity sampling until you have enough units

Question 6

Cluster

Answer 6

Split the population into (naturally occurring) clusters you expect to be similar, then either take a census of these clusters (if small) or a simple random if large.

E.g: Post codes normally identify people with similar socio economic status

Question 7

Methods that do require a sampling frame

Answer 7

Simple random

Systematic

Stratified

Question 8

Methods that DO NOT require a sampling frame

Answer 8

Opportunity

Quota

Cluster