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 4-450 Validated Customer Complaints . Validated customer complaints are
preferred:
(a) As a supplement to other methods of sampling,
(b) When the customer can be relied upon to understand the scope of the
contract and is willing to participate in an organized customer complaint
program.
4-460 Incidental Inspections . Incidental inspections are preferred:
(a) As a supplement to other methods of sampling,
(b) For services of low importance or criticality.
4-470 Inappropriate Use of Surveillance Methods. The following is
guidance on the inappropriate use of some of the surveillance methods:
(a) If a service is required, but individual occurrences are of small
importance (for example, emptying a trash can), it is normally not
beneficial to invest in 100 percent inspection - the most costly of the
inspection methods which can be employed.
(b) If a contract requirement is continuous in nature, 100 percent
inspection may not be feasible since it requires a QAE to be on site full
time. Examples of continuous requirements are manning a guard post, utility
operations, or manning a trouble desk.
(c) The defect rate, when planned sampling is used, is calculated by
dividing the total number of defects (both within and outside the sample) by
the total population. Dividing the number of defects in the sample by the
sample size gives an "Observed Defect Rate" (ODR). This ODR shall not be
used to either assess the contractor's performance or to take deductions to
the contractor's price.
(d) If the use of random sampling is appropriate, random sampling for
extrapolated deductions (RSED) should be used in preference to random
sampling without deductions (RSWED). In the case of ongoing contracts where
there was no provision in the contract to use statistically extrapolated
surveillance techniques, consideration should be given to using RSWED.
4-500 IDENTIFICATION OF THE POPULATION
4-510 Population - Defined. The population is the total number of
occurrences of an individual task or service carried out over a specified
period of time For example, the population for service calls is the number
of service calls performed in a month. (The tasks are listed as contract
requirements in the PRS.)
When identifying the population, it is important to differentiate the number
of locations at which the particular service is to be carried out from the
total number of services performed.
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