Division 1 Flag State performance shall be calculated using a standard formula for statistical calculations in which certain values are fixed. The black to grey and grey to white limits are defined by the following formulas:

United Kingdom

μ_{black_to_grey} = N · p + 0,5 + z \sqrt{N · p (1 – p)}

μ_{white_to_grey} = N · p – 0,5 – z \sqrt{N · p (1 – p)}

Where:

is the number of inspections

is the allowable detention limit

is the critical value of the normal distribution (1,645 for certainty level of 95 %)