Daily Maximum Relative Humidity (%) - above 95% associated with mist and fog
Daily Mean Visibility (Dm): 1Dm = 10m
Daily Mean Total Cloud (oktas)
Daily Mean Pressure (hPa)
Daily Mean Windspeed (knots)
Daily Mean Windspeed (Beaufort conversion) - cumulative
Daily Maximum Gust (knots)
Daily Mean Wind Direction (bearing)
Daily Mean Wind Direction (cardinal direction)
Daily Maximum Gust Direction (bearing)
Daily Maximum Gust Direction (cardinal direction) - direction wind is blowing from (eg. direction of 270º (W) means wind is blowing from West to East)
Rainfall is the only variable with ‘tr’.
Means values of rainfall less than 0.05mm.
If using it in a calculation, mean and standard deviation for example, use 0.025 (cleaning data)
Cloud cover has 9 different outcomes
Cardinal directions have 16 outcomes
The only 4 variable to have n/a are daily total sunshine, daily mean windspeed (and Beaufort conversion) and daily maximum gust
They are n/a for the first 2 weeks of May 1987
Fmax =μR
Where μ = the coefficient of friction and R = the reaction force
Find the Z value in the tables at the back
X~B(n, p)
Y~N(np, np(1-p))
Change data from discrete data to continuous
P(X = a) - P(a - 0.5 < X < a + 0.5)
P(X < a) - P(X < a − 0.5)
P(X > a) - P(X > a + 0.5)
P(X ≤ a) - P(X ≤ a + 0.5)
P(X ≥ a) - P(X ≥ a − 0.5)
For hypothesis testing, H0: ρ=0
When using the PMCC
PMCC wants to be further away from 0 than the criticalvalue
For a random sample of size n take from a random variable X, the sample mean is normally distributed with X~N(μ,((σ^2)/n)).
Census advantages and disadvantages
Advantages: Accurate
Disadvantage: Time consuming, expensive, cannot be used when testingdestroysprocess,hard to process
Sample advantage and disadvantage
Advantage: Lesstime consuming, cheaper, fewerpeople have to respond,less data needs to be processed
Disadvantage: Not as accurate, sample may notbelarge enough to give information about smallsubgroup of the population
Censusmeasures or observes every member of a population
Sample is a selection of observations taken from a subset of the population and used to find out more information about the population as a whole
Simple random sample of size n is where every sample of size n has an equal chance of being selected
Simple random sampling advantages ands disadvantages
Advantages: Unbiased, easy and cheap for small samples, equalchance of being selected
Disadvantages: Not suitable for large samples, samplingframe needed
Systematic sampling is where the requiredelements are chosen at regularintervals from an unorderedlist
Systematic sampling advantages and disadvantages
Advantages: Simple and quick, suitable for large samples
Disadvantages: Samplingframe needed, bias introduced if samplingframe is notrandom
Stratified sampling is where the population is divided into mutually exclusive strata and a randomsample is taken from each
Stratified sampling advantages and disadvantages
Ad: Accurate of population, proportional representation of groups
Dis: Population must be clearlyclassifiedinto distinct strata, notsuitable for large samples within the strata, samplingframe needed within strata
Quota sampling is where a sample is selected from a population based on a set of criteria
Quota sampling advantages and disadvantages
Ad: Allows a smallsample to represent the whole population, nosampling frame required, quick, easy, inexpensive, easy comparison between different groups within a population
Dis: Bias,population must be divided into groups - costly or inaccurate, increasingscopeofstudyincreases number of groups - increases time and expenses, non-responsesnotrecorded
Opportunity sampling is where a sample is taken from people who are available at the time of study and fit the criteria needed
Opportunity sampling advantages and disadvantages
Ad: easy and inexpensive
Dis: unlikely to provide a representativeresult,highlydependant on individual researcher
Linear Interpolation Formula
Median = (lower value of the median group) + ([{halfway} - {frequency of the groups before the median}]÷[frequency of median group]) x (width of median group)
Works for other values, not just the median, just substitute the right numbers