statistics

P(A|B)

probability of A given B

P(A and B)/P(A)

what does A and B are independent mean

one doesn’t affect the other

P(A and B) = P(A) x P(B)

P(A|B) = P(A)

what does A and B are mutually exclusive mean

P(A and B) = )

P(AUB) =P(A) +P(B)

how tow work out P(AUB)

P(A) + P(B) - P(A and B)

P(A and B)

P(A) x P(B)

what does larger IQR mean

larger spread of data/standard variation

large data set: coastal areas

generally winder

cambourne hurn leuchars perth jacksonville

normal aproximation

Y~N (mean, variance)

using B~N(n, p)

mean = np

standard deviation = square root np(1-p)

ONLY use if p is close to 0.5 and n is large >50

new probability, extend by 0.5, e.g. p>110 = P>=111 so would be p>=110.5

using Z (standards deviation)

Z~N (0, 1)

Z= (x-mean)/standard deviation

large data set: why can’t you estimate annual mean daily total rainfall in Leeming 1987

data only recorded may-october, not representative of whole year

what variables from large data set can’t be modelled by normal distributiion

daily mean windspeed: qualitative

rainfall, not symmetrical

which month in beijing has lowest temperatures

october

standard deviation

(square root)Sxx/n

OR (square root) mean of squares - square of mean