Chapter 1 - Data collection

Question 1

What is a population?

Answer 1

The whole set of items that are of interest

Question 2

What is a sample?

Answer 2

The subset of the population intended to represent that population

Question 3

What is a sampling unit?

Answer 3

Each individual thing in a population that can be sampled

Question 4

What is a sampling frame?

Answer 4

A list of individually named or numbered sampling units

Question 5

What is a census?

Answer 5

An observation or measurement of the whole population

Question 6

Advantages of using a census

Answer 6

The result should be completely accurate

Question 7

Disadvantages of using a census (3)

Answer 7

Time-consuming and expensive
Can’t be used when the testing process destroys the item
Hard to process the large amounts of data obtained

Question 8

What is a sample?

Answer 8

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

Question 9

Advantages of using a sample (3)

Answer 9

Fewer people have to respond
Less data to process
Less time-consuming and expensive

Question 10

Disadvantages of using a sample (2)

Answer 10

The data may not be as accurate

The sample might not give information about small sub-groups of the population

Question 11

What are the three methods of random sampling?

Answer 11

Simple random sampling, stratified sampling and systematic sampling

Question 12

What is simple random sampling?

Answer 12

Every sample has an even chance of being selected

Question 13

How to conduct a simple random sample?

Answer 13

Number each item and use a random number generator

Question 14

Advantages to simple random sampling (3)

Answer 14

No bias
Easy and cheap to implement
Each unit has a known and equal chance of selection

Question 15

Disadvantages to simple random sampling (2)

Answer 15

Not suitable when the population size is large - too time-consuming
A sampling frame is needed

Question 16

What is systematic sampling?

Answer 16

Required elements are chosen at regular intervals from an ordered list

Question 17

How to conduct a systematic sample

Answer 17

Take every nth element, where n = population size / sample size

Question 18

Advantages of systematic sampling (2)

Answer 18

Simple and quick

Suitable for large population/sample sizes

Question 19

Disadvantages of systematic sampling (2)

Answer 19

A sampling frame is needed

It can introduce bias if the sampling frame isn’t random

Question 20

What is stratified sampling?

Answer 20

The population is divided into strata and a random sample is carried out for each strata

Question 21

Advantages of stratified sampling (2)

Answer 21

The sample accurately reflects the structure of the population
It guarantees a proportional representation of groups within a population

Question 22

Disadvantages of stratified sampling (2)

Answer 22

The population must be clearly divided into strata
Selection from each stratum suffers the same disadvantages of simple random sampling (e.g. a sampling frame is needed ad it isn’t suitable when the sample size is large)

Question 23

What is quota sampling?

Answer 23

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

Question 24

How to conduct quota sampling

Answer 24

Divide the population into groups according to the characteristic of interest, then determine the size of each group in the sample so it is representative

Question 25

What is opportunity sampling?

Answer 25

Taking the sample from people who are around at the time the study is carried out and who fit the criteria you are looking for

Question 26

Advantages of quota sampling 3

Answer 26

No sampling frame required Quick, easy and inexpensive Easy comparison between different groups

Question 27

Disadvantages of quota sampling 3

Answer 27

Can introduce bias Dividing the population into groups can be inaccurate or costly Non-responses aren't recorded

Question 28

Advantages of opportunity sampling 2

Answer 28

Easy to carry out | Inexpensive

Question 29

Disadvantages of opportunity sampling 2

Answer 29

Unlikely to be representative | Highly dependent on the researcher

Question 30

What is qualitative data?

Answer 30

Data associated with words

Question 31

What is quantitative data?

Answer 31

Data associated with numbers

Question 32

What is a continuous variable?

Answer 32

Can take any decimal value in a range

Question 33

What is a discrete variable?

Answer 33

Can only take specific whole numbers

Question 34

What are class boundaries?

Answer 34

The minimum and maximum values in a class

Question 35

What is the midpoint?

Answer 35

The average of the class boundaries

Question 36

What is the class width?

Answer 36

The difference between the upper and lower class boundaries

Question 37

What is the daily mean temperature?

Answer 37

The average of the hourly temperature readings during a 24 hour period

Question 38

What is the daily total rainfall?

Answer 38

The amount of precipitation which falls in a day

Question 39

To what unit is the daily total sunshine recorded to?

Answer 39

The nearest tenth of an hour

Question 40

What is daily windspeed measured in?

Answer 40

Knots

Question 41

What is the daily maximum gust?

Answer 41

The highest instantaneous windspeed recorded

Question 42

What will humidities above 95% result in?

Answer 42

Misty and foggy conditions

Question 43

What is daily mean cloud cover measured in?

Answer 43

Eighths of the sky covered by cloud

Question 44

What is the daily mean visibility?

Answer 44

The greatest horizontal distance at which an object can be seen in daylight

Question 45

Where are the five UK weather stations?

Answer 45

``` Leeming Leuchars Camborne Heathrow Hurn ```

Question 46

Where are the three international weather stations?

Answer 46

Beijing Jacksonville Perth