Data Collection

Question 1

Population

Answer 1

The whole set of items that are of interest

Question 2

Census

Answer 2

Measures or observes every member of a population

Question 3

Sample

Answer 3

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

Question 4

Advantages of a Census

Answer 4

• Results should be completely accurate

Question 5

Disadvantages of a Census

Answer 5

• Time consuming and expensive
• Cannot be used when testing destroys process
• Hard to process large quantity of data

Question 6

Advantages of Sample

Answer 6

• Less time consuming and cheaper
• Fewer people have to respond
• Less data needs to be processed

Question 6

3 types of Random Sampling:

Answer 6

• Simple Random Sampling
• Systematic Sampling
• Stratified Sampling

Question 7

What are Sampling units?

Answer 7

Individual units of a population that are named and numbered to form sampling frame

Question 7

Disadvantages of Sample

Answer 7

• Data may not be accurate
• Sample may not be large enough to give information about small subgroups of the population

Question 7

What is Random Sampling?

Answer 7

• Where each member of the population has an equal chance of being selected
• The sample should be representative of the population and bias should be removed

Question 8

What is Simple random sampling?

Answer 8

Where every sampling unit in the sampling frame has an equal chance of being selected

Question 9

How to carry out Simple Random Sampling?

Answer 9

• Allocate a number between 1 and N to each sampling unit, within the sampling frame
• Use a random number generator or method of lottery sampling to select X numbers between 1 and N
• Units corresponding to these numbers become the sample

Question 10

Advantages of Simple Random Sampling

Answer 10

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

Question 11

Disadvantages of Simples Random Sampling

Answer 11

• Not suitable for large samples and populations
• Sampling frame is needed

Question 12

What is Systematic Sampling?

Answer 12

Where required elements are chosen at regular intervals in ordered list

Question 13

How to carry out a Systematic sample?

Answer 13

• Divide the population size of by the sample size to obtain the interval of k
• Then use a random generator to obtain a unit between 1 and k
• Start with the unit obtained and go up in the interval you worked out

Question 14

Advantages of Systematic Sampling

Answer 14

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

Question 15

Disadvantages of Systematic Sampling

Answer 15

• Bias introduced if sampling frame is not random
• A sampling frame is needed

Question 16

What is Stratified Sampling?

Answer 16

• Where the population is divided into strata and a simple random sample is carried out in each group
• Used when sample is large and population is naturally divided into groups

Question 17

How to carry out a Stratified Sample?

Answer 17

• Find the total number of population
• Obtain the same proportion from each strata by dividing sample size by population size and then multiplying answer by the sample size given in question
• Number the workers in each strata
• Use a random number generator to produce the required quantity of random numbers

Question 18

Advantages of Stratified Sampling

Answer 18

• Sample accurately reflects population structure
• Proportional representation of groups within population

Question 19

Disadvantages of Stratified Sampling

Answer 19

• Population must be clearly classified into distinct strata
• Sampling frame needed

Question 20

What are the two types of non random sampling:

Answer 20

• Quota sampling
• Opportunity sampling

Question 21

What is Quota sampling?

Answer 21

Where a researcher selects a sample that reflects the characteristics of the whole population

Question 22

Advantages of Quota Sampling

Answer 22

- Allows a small sample to be representative of the population - Quick, easy and inexpensive - Easy comparison between different groups within a population

Question 23

Disadvantages of Quota Sampling

Answer 23

- Can introduce bias - Population must be divided into groups which can be costly or inaccurate - Increasing scope of study increases number of groups and, which adds time and expenses

Question 24

What is Opportunity sampling?

Answer 24

Where sample is taken from people who are available at the time of study and who fits the criteria they are looking for

Question 25

Advantages of Opportunity sampling

Answer 25

- Easy and inexpensive

Question 26

Disadvantages of Opportunity Costs

Answer 26

- Unlikely to provide a representative result - Highly dependent on individual research

Question 27

What is a continuous variable?

Answer 27

- A variable that can take any value in a given range

Question 28

What is a discrete variable?

Answer 28

- A variable that can only take specific values

Question 29

What is the class width?

Answer 29

The difference between upper and lower class boundaries