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Maths - statistics > Chapter 1 - Data collection > Flashcards

Chapter 1 - Data collection Flashcards

1
Q

What is a population?

A

The whole set of items that are of interest

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2
Q

What is a sample?

A

The subset of the population intended to represent that population

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3
Q

What is a sampling unit?

A

Each individual thing in a population that can be sampled

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4
Q

What is a sampling frame?

A

A list of individually named or numbered sampling units

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5
Q

What is a census?

A

An observation or measurement of the whole population

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6
Q

Advantages of using a census

A

The result should be completely accurate

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7
Q

Disadvantages of using a census (3)

A

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

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8
Q

What is a sample?

A

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

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9
Q

Advantages of using a sample (3)

A

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

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10
Q

Disadvantages of using a sample (2)

A

The data may not be as accurate

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

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11
Q

What are the three methods of random sampling?

A

Simple random sampling, stratified sampling and systematic sampling

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12
Q

What is simple random sampling?

A

Every sample has an even chance of being selected

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13
Q

How to conduct a simple random sample?

A

Number each item and use a random number generator

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14
Q

Advantages to simple random sampling (3)

A

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

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15
Q

Disadvantages to simple random sampling (2)

A

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

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16
Q

What is systematic sampling?

A

Required elements are chosen at regular intervals from an ordered list

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17
Q

How to conduct a systematic sample

A

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

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18
Q

Advantages of systematic sampling (2)

A

Simple and quick

Suitable for large population/sample sizes

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19
Q

Disadvantages of systematic sampling (2)

A

A sampling frame is needed

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

20
Q

What is stratified sampling?

A

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

21
Q

Advantages of stratified sampling (2)

A

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

22
Q

Disadvantages of stratified sampling (2)

A

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)

23
Q

What is quota sampling?

A

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

24
Q

How to conduct quota sampling

A

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

25
Q

What is opportunity sampling?

A

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

26
Q

Advantages of quota sampling 3

A

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

27
Q

Disadvantages of quota sampling 3

A

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

28
Q

Advantages of opportunity sampling 2

A

Easy to carry out

Inexpensive

29
Q

Disadvantages of opportunity sampling 2

A

Unlikely to be representative

Highly dependent on the researcher

30
Q

What is qualitative data?

A

Data associated with words

31
Q

What is quantitative data?

A

Data associated with numbers

32
Q

What is a continuous variable?

A

Can take any decimal value in a range

33
Q

What is a discrete variable?

A

Can only take specific whole numbers

34
Q

What are class boundaries?

A

The minimum and maximum values in a class

35
Q

What is the midpoint?

A

The average of the class boundaries

36
Q

What is the class width?

A

The difference between the upper and lower class boundaries

37
Q

What is the daily mean temperature?

A

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

38
Q

What is the daily total rainfall?

A

The amount of precipitation which falls in a day

39
Q

To what unit is the daily total sunshine recorded to?

A

The nearest tenth of an hour

40
Q

What is daily windspeed measured in?

A

Knots

41
Q

What is the daily maximum gust?

A

The highest instantaneous windspeed recorded

42
Q

What will humidities above 95% result in?

A

Misty and foggy conditions

43
Q

What is daily mean cloud cover measured in?

A

Eighths of the sky covered by cloud

44
Q

What is the daily mean visibility?

A

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

45
Q

Where are the five UK weather stations?

A 
Leeming
Leuchars
Camborne
Heathrow
Hurn
46
Q

Where are the three international weather stations?

A

Beijing
Jacksonville
Perth

Maths - statistics (7 decks)

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