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FORMULARIO
QUARTILES
IQR : Q3 – Q1
SAMPLE CORRELATION COEFFICIENT :
by CENTRAL LIMIT THEOREM:
P(z>(...))
1.1) E[x]=p
MODE = the value which compares the most;
MEAN = ( 1+ …. + n)/;
MEDIAN = the central value of a DATA SET.
DISPARI : MEDIAN is the central value
PARI : MEDIAN: ( 2 central values / 2 )
IMPORTANT! FOR BOTH CASES ORDER THE DATA SET IN INCREASING ORDER!
1st : 0.25 * n
2nd : 0.50 * n it corresponds to the MEDIAN.
3rd : 0.75 * n
( Interquartile Range )
∑xy-nx(bar)y(bar)/√(∑x^2-nx(bar)^2)(∑y^2-ny(bar)^2)
1) r<0,3 : none correlation or very weak;
2) 0,3 < r < 0,5 : weak corr.;
3) 0,5 < r < 0,7: moderate corr.;
4) r>0,7 : strong corr.
DISTRIBUTION of the SAMPLE MEAN :
(x(bar)-µ)/(o/√n)
P{X<=a} = P{(x(bar)-µ/(o/√n) <= (a-µ)/(o/√n)} # 1-(P<=z) when
I must calculate
Z : standardized
variable
SAMPLING PROP. From a finite POP:
1) E[x] = np
2) SD[x] = √np(1-p) 2.1) SD[x]= √(p(1-p))/n
X(bar) = sample mean of a sample size “n” from a population
having mean µ
1) E[x(bar)] = µ
2) SD[x(bar)]=(o/√n)
