M - Statistics & Mechanics 1 - 1) Data collection

Question 1

Definition of a population

Answer 1

The whole set of items that are of interest

Question 2

Benefits and drawbacks of censuses

Answer 2

Benefits:

• Should give a completely accurate result

Drawbacks:

• Time consuming and expensive
• Cannot be used when the testing process destroys the item

Question 3

Definition of a sample

Answer 3

A subset of the population which is used to find out information about the population as a whole

Question 4

Benefits and drawbacks of samples

Answer 4

Benefits:

• Less time consuming and expensive than censuses

Drawbacks:

• Data may not be as accurate or generalisable

Question 5

All types of sampling

Answer 5

Random:

• Simple random
• Systematic
• Stratified

Non-random:

• Quota
• Opportunity

Question 6

Definition of simple random sampling

Answer 6

Where every sample has an equal chance of being selected

Question 7

Definition of systematic sampling

Answer 7

The sample is chosen at regular intervals from an ordered list

Question 8

Definition of stratified sampling

Answer 8

The population is divided into different strata and a random sample is taken from each

Question 9

Formula for stratified sampling

Answer 9

Number sampled in stratum = (number in stratum ÷ number in population) × overall sample size

Question 10

Definition of quota sampling

Answer 10

Selecting a sample that reflects the characteristics of the whole population

Question 11

Definition of opportunity sampling

Answer 11

Taking the sample from people who are available at the time and who fit the criteria being looked for