Chapter 1 - Data Collection

Question 1

Define population:

Answer 1

The entire set of items of interest

Question 2

Define census:

Answer 2

When data is collected from every member of a population

Question 3

Define sample:

Answer 3

A set of observations taken from a subset of the population

Question 4

Advantages of a census:

Answer 4

Completely representative

Question 5

Disadvantages of a census:

Answer 5

Time consuming, expensive and can’t be used if the item needs to be destroyed in the testing process

Question 6

Advantages of a sample:

Answer 6

Cheaper, quicker, less data to process

Question 7

Disadvantages of a sample:

Answer 7

May be less accurate, may not be enough to give info about small subsets of a population

Question 8

Define sampling unit:

Answer 8

An individual in the population

Question 9

Define sampling frame:

Answer 9

An ordered list of sampling units

Question 10

What is a simple random sample:

Answer 10

The number of sample units needed are randomly selected from the entire population

Question 11

What is systematic sampling:

Answer 11

When every nth sampling unit is selected from a random starting point

Question 12

What is stratified sampling:

Answer 12

The population is divided into mutually exclusive strata and a proportionate number of sampling units are randomly selected from each

Question 13

How to calculate the sample size for a strata:

Answer 13

(Strata size/population size) * sample size

Question 14

Advantages of simple random sampling:

Answer 14

Bias free, easy, cheap, everyone gets an equal chance

Question 15

Disadvantages of simple random sampling:

Answer 15

Needs a sampling frame, not suitable for large populations as it gets expensive and time-consuming

Question 16

Advantages of systematic sampling:

Answer 16

Easy, quick, good for large populations

Question 17

Disadvantages of systematic sampling:

Answer 17

Needs a sampling frame, can introduce bias

Question 18

Advantages of stratified sampling:

Answer 18

Accurately reflects population structure, guarantees proportional representation

Question 19

Disadvantages of stratified sampling:

Answer 19

Population needs to be classified, same issues as simple random within the strata

Question 20

What is opportunity/convenience sampling:

Answer 20

Collecting data from the first sampling units you find

Question 21

What is quota sampling:

Answer 21

Opportunity sampling, but according to different quotas so there’s proportional representation

Question 22

Advantages of quota sampling:

Answer 22

A small sample can still be representative, no sampling frame, quick, easy, cheap, allows for easy comparison

Question 23

Disadvantages of quota sampling:

Answer 23

Can introduce bias, population needs to be classified

Question 24

Advantages of opportunity/convenience sampling:

Answer 24

Easy, cheap

Question 25

Disadvantages of opportunity/convenience sampling:

Answer 25

Unlikely to be representative, depends on individual researcher

Question 26

What is a discrete variable:

Answer 26

Non-continuous, like colour or number of people