sampling Flashcards
advantages of simple random sampling
free of bias
cheap and easy for small
equal chance
disadvantages of simple random sampling
not suitable for large sets
sampling frame needed
advantages of census
completely accurate
disadvantages of census
expensive
time consuming lots of data
difficult to ensure whole population
advantages of a sample
less time consuming
fewer people than census
less data
disadvantages of sample
not accurate
may bot be large enough to represent population
advantages of systematic sampling
simple and quick
suitable for large sets
disadvantages of systematic sampling
sampling frame
introduce bias if it’s not random
advantages of stratified sampling
accurately refelects population structure
proportional representation of groups
disadvantages of stratified sampling
population clearly classified into distinct strata
selection within stratum suffers from disadvantages as simple random
advantages of quota sampling
small sample represent
no sampling frame
quick and easy
easy comparison
disadvantages of quota
introduce bias
must be divided into groups
increasing scope of study and expense
non responses nokt recorded
advantages of opportunistic sampling
easy to carry out
inexpensive
disadvantages of opportunity sampling
unlikely to be provided representitivelt
dependant on researcher
advantages of random
no bias
clear on method
advantages of non random
useful when no sampling frame
useful if it’s difficult to reach
disadvantages of random sampling
might not want to take part
sampling frame
disadvantages of no. random
samples likely to be unrepresentative
researcher may be swayed
what is continuous data
has to be measured and can take a value between any two points
what is discrete data
if values are distinct and separate - counted
how do you cleanse data
Q3+k(Q3-Q1)
where is AnB
in the middle of the venn
What are the 5 weather stations in the UK
Leuchars
Leeming
Camborne
Hurn
Heathrow
Where is leuchars
Scotland
Where is leeming
North yorkshure
Where is Heathrow
Near London
Where is hurn
Bournemouth
Where his Camborne
Cornwall
Where are the oversea weather statins
Jacksonville
Beijing
Perth
Where is Jacksonville
SE coat US
What variables are recorded
Daily maximum temp (C)
Daily total rainfall (mm)
Daily total sunshine daily maximum relative humidity (%)
Daily mean wind speed (knots)
Daily maximum gust
Wind direction and gust (bearing)
Visibility (dm décamètres)
Pressure (hPa)
What is the Beaufort scale
Discrete scale of 13 values 0-12
Wind speed and gust
0=calm
12=64knots
What are okras
Eights of the sky covered by cloud
0-8
Discrete scale
What does tr mean in data set
Trace amounts eg >0.05mm
What happened in 1987
Great storm UK -October
hurricane floyd USA October
