By the use of the number of deaths in the Continuous Mortality Investigation and the number of impaired lives in a small sample of recently issued policies an estimate is made of the extent of the data likely to be available from the records of the life offices for an investigation into extra mortality. It is estimated that for several impairments the ratio of actual to expected deaths for all ages and durations combined could be obtained with a standard error of 10% or less, but only the broadest conclusions could be drawn as to the distribution of the extra mortality according to age and duration.

The experience of normal lives obtained by a control investigation by individual cards is suggested as a standard, two policies on normal lives being included for each policy in the special investigation. The possibility is considered of using the data of the control investigation to throw fresh light on some of the mortality problems which cannot be solved by use of the data as at present returned to the Continuous Mortality Investigation.

A brief outline is given of the form an investigation should take and it is suggested that it should also include the investigation of the mortality of certain other special classes including female lives and lives assured for large sums.