Fact box – Uncertainty in resource estimates

Uncertainty expresses the range of possible resource outcomes or results. It is most frequently described with the aid of low and high estimates.

The NPD estimates the undiscovered resources on the NCS to be 2 140-6 020 million scm oe. This uncertainty is calculated using a statistical method known as Monte Carlo simulations. The high and low estimates are described utilising statistical concepts.

Where undiscovered resources are concerned, the NPD uses P95 for the low estimate. This means that, given the assumptions applied in the analysis, the probability of a result equal to or larger than the P95 value is 95 per cent.

P05 is used for the high estimate, which means a five per cent probability that the result will be equal to or larger than the P05 value.

The expected value is the average value. This is generally defined as the arithmetic mean of all the outcomes in the statistical distribution. Widely used, it has the property that the expected value for various distributions can be summed to give a sum of distributions.