31.   Perfect information is usually not practicable but the concept is useful in establishing how much can be paid for whatever additional information is available.

32.   As already seen in this chapter, such perfection is not to be expected and the probability of the additional information being accurate must be taken into account.

33.   In this case the benefit from the additional information is less than the cost of obtaining it.

34.   Some heads of departments had used the summer vacation to write the bulk of their reports but sometimes advisers requested additional information in subsequent visits.

35.   In many cases the additional information simply added weight to what has already been dealt with in the attitude scales.

36.   Nonetheless, it is clear that accident estimates still provide additional information.