Year 1

Question 1

In statistics, what is a population?

Answer 1

A whole set of items that are of interest.

Question 2

What is a census?

Answer 2

An observation or measure of every member of a population.

Question 3

What is a sample?

Answer 3

A selection of observations taken from a subset of the population which is used to find out information about the population as a whole.

Question 4

What are the advantages and disadvantages of a census?

Answer 4

Gives a completely accurate result.
However,
Is time consuming and expensive
Cannot be used when the testing process destroys the item
It is harder to process larger quantities of data.

Question 5

What are the advantages and disadvantages of a sample?

Answer 5

Less time consuming and less expensive than a census
Fewer people are needed to respond
There is less data to process than a census
However,
Data may not be accurate
The sample group may not be large enough to represent the population.

Question 6

What is a sampling unit?

Answer 6

Individual units of a population.

Question 7

What is random sampling?

Answer 7

Where every member of the population has an equal chance of being selected. The sample should be representative of the population. Random sampling removes bias from a sample.

Question 8

What are the 3 methods of random sampling?

Answer 8

Simple random sampling
Systematic sampling
Stratified sampling

Question 9

What is a brief description of simple random sampling?

Answer 9

A random sample of size n is one where every sample of size n has an equal chance of being selected

Question 10

Brief description of stratified sampling?

Answer 10

The population is divided into mutually exclusive strata and a random sample is taken from each. The proportion of each strata samples should be the same.

Question 11

Brief description of systematic sampling?

Answer 11

Required elements are chosen at regular intervals from an ordered list.

Question 12

Advantages and disadvantages of simple random sampling?

Answer 12

Removes bias
easy and cheap to implement into small populations
Each sampling unit has an equal chance of selection
However,
not suitable for larger sample/population sizes
A sampling frame is needed

Question 13

Advantages and disadvantages of systematic sampling?

Answer 13

Simple and quick to use
suitable for large sample/population sizes
However,
Requires a sampling frame
Can introduce bias if the sampling frame is not random

Question 14

Advantages and disadvantages of stratified sampling?

Answer 14

Sample accurately reflects the population
Guarantees proportional representation of groups within a population
However,
Population must be clearly classified into distinct strata
Selection within each strata suffers from the same disadvantages as simple random sampling.

Question 15

What are the 2 types of non-random sampling?

Answer 15

Quota sampling

Opportunity sampling

Question 16

What is quota sampling?

Answer 16

An interviewer manually selects a sample that reflects the characteristics of the whole population. The interviewer would select people to fulfil a quota.

Question 17

What is opportunity sampling?

Answer 17

A sample taken from the people that are available at the time of study.

Question 18

Advantages and disadvantages of quota sampling?

Answer 18

Allows a small sample to still be representative of the population
No sampling frame required
quick, easy and inexpensive
Allows for easy comparison between different groups
However,
Can introduce bias
population must be divided into groups
larger scope of study increases time and cost
Non-responses are not recorded as such

Question 19

Advantages and disadvantages of opportunity sampling?

Answer 19

Easy and inexpensive
However
Unlikely to be representative
highly dependant on individual researcher