AGGREGATION AND DEPENDENCY


     To arrive at the estimated quantity of undiscovered resources for
large areas, such as provinces, regions, or the Nation as a whole,
distributions estimated for basic assessment units were progressively
aggregated, with geological dependency incorporated at each level. In
order to aggregate plays within provinces, geologic dependencies
between plays were established for the three basic attributes of
charge, reservoir, and trap. Province geologists determined for each
pair of plays in their province whether the correlation was high (0.9),
moderate (0.5), or low (0.1) for each attribute. Thus, to determine the
degree of dependency of plays A and B, if highly correlated with
respect to charge (0.9), poorly correlated with respect to reservoirs
(0.1), and moderately correlated with respect to trap (0.5), the mean
correlation value was calculated to be (0.9+0.1+0.5)/3, or 0.5. This
value of dependency would be used in aggregating plays A and B. For the
aggregation of province-level estimates, the provinces within each
region were assigned a dependency of 0.5. In aggregation of regions for
a national total, regions were considered to be independent.