STATSY1 ch1 populations and samples

Question 1

Census

Answer 1

Observes or measures every member of a population

Question 2

Census advantages

Answer 2

• should give a completely accurate result

Question 3

Census disadvantages

Answer 3

• time consuming and expensive
• cannot be used when process destroys item
• hard to process large quantity of data

Question 4

Sample

Answer 4

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

Question 5

Sample advantages

Answer 5

• less time consuming and expensive than a census
• fewer people have to respond
• less data to process than a census

Question 6

Sample disadvantages

Answer 6

• data may not be as accurate
• sample may not be large enough to give information about small sub sets of population

Question 7

Sampling units

Answer 7

Individual units of a population

Question 8

Sampling frame

Answer 8

Sampling units named or numbered to form a list

Question 9

Three methods of random sampling

Answer 9

• simple random sampling
• systematic sampling
• stratified sampling

Question 10

Simple random sample

Answer 10

• every sample has an equal chance of being chosen

Question 11

Simple random sample advantages

Answer 11

• free of bias
• easy and cheap to implement for small populations
• each sampling unit has an equal chance of being chosen

Question 12

Simple random sample disadvantages

Answer 12

• not suitable for large population
• a sampling frame needed

Question 13

Systematic sample

Answer 13

• required elements chosen at regular intervals from an ordered list

Question 14

Systematic sample advantages

Answer 14

• simple and quick to use
• suitable for large populations

Question 15

Systematic sample disadvantages

Answer 15

• sampling frame is needed
• can introduce bias if frame not random

Question 16

Stratified sample

Answer 16

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

Question 17

Stratified sample advantages

Answer 17

• sample accurately reflects population structure
• guarantees proportional representation of groups within a population

Question 18

Stratified sample disadvantages

Answer 18

• population must be distinctly classified into distinct strata
• selection within each stratum suffers from same disadvantages as simple random sampling

Question 19

Types of non-random sampling

Answer 19

• quota
• oppurtunity

Question 20

Quota sampling

Answer 20

An interviewer selects a sample that reflects characteristics of population

Question 21

Quota advantages

Answer 21

• allows small sample to be representative of population
• no sampling frame needed
• quick, easy and inexpensive
• allows for easy comparison of different groups

Question 22

Quota disadvantages

Answer 22

• non-random can introduce bias
• population must be divided into groups which is costly and inaccurate
• increasing scope of study increases number of groups, adding time and expense
• non-responses are not recorded

Question 23

Oppurtunity sampling

Answer 23

• taking a sample of people available at time of study who fit criteria

Question 24

Oppurtunity sampling advantages

Answer 24

• easy to carry out
• inexpensive

Question 25

Oppurtunity sampling disadvantages

Answer 25

- unlikely to provide a representative sample - dependant on individual researcher

Question 26

Qualitative data

Answer 26

- non-numerical observations

Question 27

Quantitative data

Answer 27

- numerical observations

Question 28

Continuous data

Answer 28

- can take any value in a given range

Question 29

Discrete data

Answer 29

- can only take specific values in a given range