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Statistical Tables

General

Variations, probabilities of non-exceedance and return periods can be computed for the following frequency distributions:

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The distributions 1 to 14 are described in the previous paragraph. The distributions 15 and 16 are presented in the next paragraph. The data requirements for this option are dealt with in the last section of this paragraph.

Frequency distributions

Reference is made to the previous paragraph for the description of the distributions 1 to 14. The Student t-distribution and Fisher F-distribution are presented below.

Student t-distribution:

The probability of non-exceedance is given by:

with:

Fisher F-distribution:

The F-distribution is a ratio of two Chi-square distributed variables with respectively m and n degrees of freedom, where the Chi-square in its turn is a sum of squared standardised normally distributed variables; the number of elements in the sum is the degree of freedom.
The probability of non-exceedance is given by:

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with:
m, n = degrees of freedom
mean = m/(n+1)
st. dev. = n √((m+2)/(m(n-2)(n-4))

Data input

The type of data required to use the statistical tables is twofold:

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