Difference estimation is a classical variable sampling technique used by auditors to estimate the total misstatement in an account balance. It works by analyzing the average difference between the recorded (book) values and the audited (actual) values within a representative sample, then projecting that difference across the entire population. This method is effective when differences are relatively consistent and when the objective is to estimate a total dollar misstatement.

To apply difference estimation, the auditor calculates the total difference between the book and audit values in the sample, divides it by the number of sample items to find the average difference, and then applies this average to the total number of population items or to the population book value.

Practical Example:
Suppose an auditor tests a sample of 500 accounts with a total book value of $580,000 and finds the audited value to be $600,000—indicating a total understatement of $20,000 in the sample. The population consists of 6,200 accounts with a total book value of $7,120,000.

Using difference estimation:

Projected Misstatement =

The projected understatement of $245,518 suggests that the overall population may be materially understated, prompting the auditor to consider potential adjustments or further procedures