Topic 1: Data Collection

Question 1

Define the word CENSUS

Answer 1

When every member of a population is included

Question 2

Give THREE disadvantages of using a census

Answer 2

• Time consuming and expensive
• Can not be used when testing involves destruction
• Large volume of data to process

Question 3

Define the word POPULATION

Answer 3

The whole set of items that are of interest

Question 4

Define the word SAMPLE

Answer 4

Small subset of the population intended to represent a population

Question 5

Give TWO disadvantages of using a sample

Answer 5

• Data may not be accurate

- Data may not be large enough to represent small sub-groups

Question 6

Give ONE advantage of using a census

Answer 6

• It should give completely accurate results

Question 7

Give THREE advantages of using a census

Answer 7

• Cheap
• Quick
• Less data to process compared to using a census

Question 8

Define the term SAMPLING FRAME

Answer 8

A list of sampling inits which may be the whole population or may represent a population as accurately as possible.

Question 9

Define the term SAMPLING UNIT

Answer 9

Individual member of a population

Question 10

State TWO reason why someone would use a RANDOM SAMPLING METHOD

Answer 10

• Efforts to avoid bias (prevents sample from being representative of the population)
• Equal chance of being choses

Question 11

Define the term RANDOM SAMPLING

Answer 11

Simple random sample of size n is one where every sample size n has an equal chance of being selected

Question 12

Give THREE advantages of using random sampling

Answer 12

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

Question 13

Give TWO disadvantages of using a random sample

Answer 13

• Sampling frame is needed

- Expensive, disruptive and time consuming if sample size is too large

Question 14

How would LOTTERY sampling be conducted?

Answer 14

Members of simplify frame would be written out on tickets and placed into a ‘hat’. The required number of tickets would then be drawn out.

Question 15

Define SYSTEMATIC SAMPLING

Answer 15

The required elements are chosen at regular intervals from an ordered list.

Question 16

How would you carry out systematic sampling on a sample size of 20 being required form a population of 100.

Answer 16

• You would take every FIFTH person (100/20=5).
• The first person will be chosen at random e.g from a random number generator.
• If the first person in number 2 in the list, the remaining sample would be persons, 7 , 12 , 17 , etc…

Question 17

Give TWO advantages of systematic sampling

Answer 17

• Simple and quick to use

- Suitable for large samples and populations

Question 18

Define STRATIFIED SAMPLING

Answer 18

The population is divided into mutually exclusive strata (male and females for example) and a random sample is taken from each.

Question 19

Give the formula associated to stratified sampling

Answer 19

The number sampled in a stratum=( no. of stratum/no. of population ) x Overall sample size

Question 20

Give TWO advantages of stratified sampling

Answer 20

• Sample accurately relates the population structure

- Guarantees proportional representation of groups within a population.

Question 21

Give TWO disadvantages of stratified sampling

Answer 21

• Population must be clearly classified into distinct strata.
• Selection within each stratum suffers from the same disadvantages as simple random sampling.

Question 22

Define the term OPPORTUNITY SAMPLING

Answer 22

It consists of taking the sample from people who are available at the time the study is carried out and two fits the criteria that you are looking for.

Question 23

Give TWO advantaged of opportunity sampling

Answer 23

• Inexpensive

- Easy and quick to carry out

Question 24

Give Two disadvantages of opportunity sampling

Answer 24

• Unlikely to give a representative sample

- Highly dependant on individual researcher

Question 25

Define the term QUOTA SAMPLING

Answer 25

An interviewer or researcher selects a sample that reflects the characterises of the whole population.

Question 26

Give FOUR advantages of quota sampling

Answer 26

• Allows a small sample to still be representative of the population
• No sample frame required
• Quick, easy and inexpensive
• Allows for easy comparison between different groups within the population

Question 27

Give THREE disadvantages of quota sampling

Answer 27

• Non-random sampling can introduce bias
• Population must be divided into groups which can be costly and inaccurate
• Non-responses are not recorded as such