Statistics (Unit 1) - Data Collection

Question 1

What is a census?

Answer 1

A census observes or measures every member of a population.

Question 2

What is a sample?

Answer 2

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 3

Adv of a Census

Answer 3

It should give completely accurate result.

Question 4

Adv of a Sample

Answer 4

• Less time consuming and expensive than a census
• Fewer people have to respond
• Less data to process than in a census

Question 5

Dis of a Census

Answer 5

• Time consuming/expensive

- Hard to process large quantities of data

Question 6

Dis of a Sample

Answer 6

• The data may not be as accurate

- Sample may not be large enough to give enough info about smaller groups of the population

Question 7

Simple random sampling

Answer 7

Where every sample has an equal but random chance of being selected

Question 8

Systematic sampling

Answer 8

Required elements are chosen at regular intervals from an ordered list

Question 9

Stratified sampling

Answer 9

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

Question 10

Adv of Simple random sampling

Answer 10

• Free of bias
• Easy and cheap for small samples
• Each unit has equal
  chance of being selected

Question 11

Adv of Systematic sampling

Answer 11

• Simple and quick

- Suitable for large samples

Question 12

Adv of stratified sampling

Answer 12

• Accurately reflects population structure

- Shows proportional representation of groups in a population

Question 13

Dis of simple random sampling

Answer 13

• Not suitable for large sizes

- Sampling frame is needed

Question 14

Dis of systematic sampling

Answer 14

• Sampling frame needed

- Can introduce bias if frame is not random

Question 15

Dis of Stratified sampling

Answer 15

• Population must be clearly classified into distinct strata

- Selection in each stratum suffers from same Dis as simple random sampling

Question 16

Quota sampling

Answer 16

An interviewer/researcher selects a sample that reflects the characteristics of the whole population

Question 17

Opportunity sampling

Answer 17

Taking the sample from people who are available at the time the study is carried out and who fit the criteria you are looking for

Question 18

Adv of Quota sampling

Answer 18

• Allows small samples to be representative of the population
• No sampling frame
• Quick, easy, inexpensive
• Easy comparison between different groups

Question 19

Adv of Opportunity sampling

Answer 19

• Easy to do

- Inexpensive

Question 20

Dis of Quota sampling

Answer 20

• Non random, can induce bias
• Population is divided into groups which can be costly/inaccurate
• More groups mean more time and expense
• Non-responses not recorded

Question 21

Dis of Opportunity sampling

Answer 21

• Unlikely to provide representative sample

- Highly dependant of individual researcher

Question 22

Quantitative data

Answer 22

Data associated with numerical observations

Question 23

Qualitative data

Answer 23

Data associated with non-numerical observations

Question 24

Continuous data

Answer 24

Data that can take any value in a given range

Question 25

Discrete data

Answer 25

Data that can take only specific values in a given range