Maths stats

Question 1

Census

Answer 1

Observes/ measures every member in a population

Question 2

Sample

Answer 2

A selection of observations taken from a subset of population

Question 3

Advantages to census

Answer 3

Results should be completely accurate

Question 4

Disadvantages to census

Answer 4

Time consuming and expensive
Can’t be used for testing as it may destory the products

Question 5

Advantages to sampling

Answer 5

Not as time-consuming as a census
Cheaper than census

Question 6

Disadvantages to sampling

Answer 6

Data not representative of entire population, therefore may be inaccurate

Question 7

Random sampling and three types

Answer 7

Each member of the population has an equal chance of being selected
Simple random sampling
Systematic sampling
Stratified sampling

Question 8

Population

Answer 8

Whole set of items of interest

Question 9

How to carry out a simple random sample

Answer 9

1) Number each member
2) Use a random number generator to generate n amount of numbers
3) Select the members who corrospond to the numbers

Question 10

Advantages of a simple random sample

Answer 10

• Free of bias
• Each unit has a known and equal chance of selection
• Easy and cheap for small samples

Question 11

Disadvantages of a simple random sample

Answer 11

• Cannot be used for large samples/ populations
• Sampling frame needed

Question 12

How to carry out a systematic sample

Answer 12

1) Number each member
2) Find the interval (k) by dividing the population size by the sample size
3) Choose a random starting point between 1 and k using a random number generator
4) Select every kth term after that

Question 13

Advantages of a systematic sample

Answer 13

• Simple and quick to use
• Suitable for large samples and large populations

Question 14

Disadvantages of a systematic sample

Answer 14

• A sampling frame is needed
• Bias introduced if sampling frame is not randomly ordered

Question 15

How to carry out a stratified sample

Answer 15

1) Divide the population into different groups
2) Work out how many people to sample from each group using:
number in sample = (group size/ total population) x sample size
3) Randomly select the required number for each group

Question 16

Advantages of stratified sampling

Answer 16

Proportional representation of groups within the population

Question 17

Disadvantages of stratified sampling

Answer 17

• Must be clearly stratified into each stratum
• Same disadvantages of simple random sampling within each stratum

Question 18

Two types of non-random sampling

Answer 18

Quota sampling
Opportunity sampling

Question 19

How to carry out quota sampling

Answer 19

1) Divide the population into different groups
2) Work out how many people you need from each group, so they match the population’s proportions
3) Collect responses from each group until the quota is filled

Question 20

Advantages of quota sampling

Answer 20

• Allows a small sample to still be representative of the entire population
• No sampling frame needed
• Quick, easy and inexpensive

Question 21

Disadvantages of quota sampling

Answer 21

• Populations must be divided into groups, which may be costly or inaccurate
• Non-responses not recorded

Question 22

How to carry out opportunity sampling

Answer 22

1) Choose people who are easiest to access at the time
2) Collect data from them until your sample size is reached

Question 23

Advantages of opportunity sampling

Answer 23

• Easy and inexpensive

Question 24

Disadvantages of opportunity sampling

Answer 24

• Unlikely to provide a representative result
• Highly dependent on individual researchers

Question 25

Quantative data

Answer 25

When variables or data are associated with numerical observation

Question 26

Qualitative data

Answer 26

When variables or data are associated with non-numerical observations

Question 27

Continuous variable

Answer 27

A variable that can take any value in a given range

Question 28

Discrete variable

Answer 28

A variable that can only take specific values