Chapter 1

Question 1

Definition of population?

Answer 1

Whole set of items of interest

Question 2

Definition of sample?

Answer 2

A subset of the population that represents the population

Question 3

Define a sampling unit?

Answer 3

Each individual thing in a population that is sampled

Question 4

Define sampling frame?

Answer 4

A list of sampling units of a population

Question 5

Define census?

Answer 5

Data collected from the whole population

Question 6

Advantages and disadvantages of a census?

Answer 6

• gives the actual result, completely accurate
  x time consuming, expensive, large volume of data

Question 7

Advantages and disadvantages of sampling?

Answer 7

• cheaper, quicker, less data to process
  x less accurate, not as representative of the whole population

Question 8

What are the random sampling methods?

Answer 8

Simple random sampling
Systematic sampling
Stratified Sampling

Question 9

What is simple random sampling? Adv & disav:

Answer 9

Label each item and use a random number generator. The corresponding numbers become samples
- bias free
- easy + cheap
- equal chance of being picked
x not suitable for larger population
x sampling frame needed

Question 10

What is systematic sampling? Adv & Disadv:

Answer 10

Required elements are chosen at random intervals. Every kth element. (k = pop size/sample size)
- simple + quick
- suitable for larger population
x can introduce bias if not evenly distributed population
x sampling frame needed

Question 11

What is stratified sampling? Adv & Disadv:

Answer 11

Population is divided into groups (strata) and a simple random sample is carried out
The same proportion is sampled from each strata (sample size / population size = proportion)
- used for large populations
- reflects the population
- guarantees proportional representation
x population must be distinctly classified
x same disadvantages as simple random

Question 12

What are the non random sampling techniques?

Answer 12

Quota sampling
Opportunistic/convenience sampling

Question 13

What is quota sampling? Adv & Disadv:

Answer 13

Population is divided into groups according to a characteristic. A quota of items/ people on each group is set to try reflect the groups proportion in the whole population.
- allows small sample to still be representative
- no sampling frame required
- quick, easy, inexpensive
- easy to compare between groups
x bias
x population must be divided into groups
x non responses aren’t recorded

Question 14

What is opportunistic/convenience sampling? Adv & Disadv:

Answer 14

Sample taken from people who are available at time of study, who meet the criteria
- easy to carry out
- inexpensive
x unlikely to provide a representative sample
x highly dependant on the individual researcher

Question 15

What is discrete data? What is continuous?

Answer 15

Discrete = specific values (shoe size)
Continuous = large range of values (height)