The three methods of random sampling

Question 1

What is simple random sampling ?

Answer 1

One where every sample of size n has equal chance of being selected

Question 2

What is systematic sampling ?

Answer 2

The required elements are chosen at regular intervals from an ordered list and the starting point is chosen randomly

Question 3

What is stratified sampling ?

Answer 3

Population is divided into mutually exclusive strata and a random sample selected from each
Number sampled = number in stratum/number in population * overall sample size

Question 4

What are the advantages and disadvantages of simple random sampling ?

Answer 4

Free of bias
Easy and cheap to implement

Sampling frame needed
Sample size large- not suitable

Question 5

What are the advantages and disadvantages of systematic sampling ?

Answer 5

Simple and quick to use
Suitable for large samples

Sampling frame needed
Introduces bias if sampling frame not random

Question 6

What are the advantages and disadvantages for stratified sampling ?

Answer 6

Sample accuracy reflects the population
Population must be clearly c,as sifted into distinct data