1.3.3.2.1 95 % CI for average loss

Like other proportions, average loss confidence intervals can be calculated using equation 1.1.2.c. As mentioned previously, average losses are often skewed by smaller operations resulting in a Poisson distribution of losses rather than a normal distribution. When the number of respondents exceeds 100, the Poisson distribution resembles a normal distribution so adjustment in the equation 1.1.2.c is not needed. However, when the number of respondents is less than 100, the rate multiplier for the 95% CI can be determined by looking up the lower and higher rate multiplier in an appropriate table (e.g. Paoli et al., 2002) (Box 3.).