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Maths > Large Data Set/Sampling Methods > Flashcards

Large Data Set/Sampling Methods Flashcards

1
Q

Locations included in large data set?

A

Leuchars: town in Scotland
Leeming: village in North Yorkshire
Heathrow: hamlet in Greater London
Hurn: village in Dorest (South West England)
Camborne: town in Cornwall (South West England)
Beijing: capital city of China
Perth: capital city of Western Australia
Jacksonville: city in Florida

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2
Q

Units/time of measurement of daily mean temp?

A

Celsius
0900-0900

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3
Q

Units/time of measurement of daily total rainfall ?

A

Millimetres - 1dp
0900-0900
‘Tr’ is amount less than 0.05mm

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4
Q

Units/time of measurement of daily total sunshine?

A

Hours - 1dp
From midnight

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5
Q

Units/time of measurement of daily max relative humidity?

A

%
Reading above 95% = mist/fog

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6
Q

Units/time of measurement of daily mean wind speed and direction?

A

Knots (1Kn = 1.15mph) - nearest integer
Can be described using Beaufort conversion - qualitative

Direction measured in degrees - rounded to nearest 10
Averaged for 24 hrs from 0000

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7
Q

Units of daily max gust and direction? What is it?

A

Knots
- max instantaneous speed over 24 hrs

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8
Q

Units/time of measurement of cloud cover?

A

Measured in Oktas - eighths of the sky covered
- discrete qualitative data

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9
Q

Units/time of measurement of daily mean visibility?

A

Decametres (1Dm = 10m )

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10
Q

Units/time of measurement of daily mean pressure?

A

Hectopascals (1hPa = 100 Pa = 1 millibar)

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11
Q

What do international cities have data for?

A

Daily mean temperature
daily total rainfall
daily mean pressure
daily mean windspeed

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12
Q

What data is missing for the UK?

A

The total daily total sunshine, mean windspeed and maximum gust is unknown for the first half of May 1987 for the UK cities

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13
Q

What locations are on coast ?

A

Jacksonville
Perth - southern hemisphere so have winter when its our summer
Camborne
Hurn
Leuchars

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14
Q

When did great storm happen and what is impact of this?

A

15-16 Oct 1987
- south east England affected - skew some variables (wind, gust, rainfall) not sunshine/cloud cover

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15
Q

What is a census? AD/DIS

A

Observe and measures every member of population
AD: gets accurate results
DIS : time consuming/expensive
Hard to process large amount of data

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16
Q

What is a sample?AD/DIS?

A

Subset of population who is used to collect data from \
AD: quicker /cheaper than census
- less data to process

DIS : not as accurate
- not representative /introduce bias

17
Q

Sampling frame?

A

list of all members of the population

18
Q

AD/DIS simple random sampling?

A

AD: free of bias
Easy and cheap

DIS: not suitable for large sample size
Sampling frame needed

19
Q

AD/DIS systematic sampling?

A

AD: Simple and quick to use
- good for larger samples

DIS : sampling frame needed
- introduce bias

20
Q

AD/DIS stratified sampling?

A

AD: reflects population structure
Guarantees proportional representation of groups within population

DIS : population need to be put into strata
- sampling within strata has same dis as simple random sampling (sampling frame needed)

21
Q

Quota sampling AD/DIS?

A

AD: no sampling frame needed
Quick ,easy, inexpensive
Allow small sample to represent population

DIS : non random sampling introduce bias
- pop must be divided into groups - costly/inaccurate

22
Q

Opportunity sampling AD/DIS?

A

AD: easy to carry out
Inexpensive

DIS : not representative
Dependent on researcher

23
Q

How to carry out systematic sampling?

A

Choose members of population at regular intervals
- to find size of interval :
Size of population (N) / size of sample (n)

  • choose starting point randomly and use regular interval from there
24
Q

How to carry out stratified sample?

A

Population divided into strata /random sample taken in each strata

No. Members sampled in strata : (size of sample (n) / size of population (N) ) x sample size

25
Q

How to carry out quota sampling?

A

Population split into groups /members selected until each quota is filled
- size of group proportional to amount of ppl in pop that should have characteristic

Maths (1 decks)

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