DLA TROOP SUPPORT SUBSISTENCE INSPECTION MANUAL 4155.6 *

SUBSECTION 203.2

AUGUST 2011 *

COMPARABILITY PROCEDURES

FOR ATTRIBUTES REINSPECTION OF UNREWORKED LOTS

I. PURPOSE AND SCOPE. This Subsection provides procedures for determining 

comparability of original inspection results with reinspection results of unreworked lots and 

instructions for determining whether or not the lot is conforming based on the comparability 

determinations and contractual requirements. These procedures apply to veterinary/medical 

inspection personnel and to all reinspections of unreworked lots meeting the criteria with the 

exception detailed in paragraph VI.

II. POLICY. These procedures apply only to inspection and reinspection for attributes and to 

defects having Acceptable Quality Levels (AQLs). If no AQL is specified and the finding of one 

or more defects is cause for rejection, comparability determinations are not necessary; 

Government results shall be used as the basis for determining if a lot is conforming. 

Reinspection sampling plans must be the same as original sampling plans regarding pertinent 

AQL(s), severity of inspection, and sample size(s). Normally, reinspections are only 

conducted for AQLs where the number of defects equalled or exceeded the rejection number 

on original inspection.

III. BACKGROUND. Comparability determinations are intended to resolve the question of 

whether or the difference(s) between original and reinspection results are due to “luck of the 

draw” only, or whether they are due to “real” differences in inspection procedures. Examples 

of the latter include sample selection, scoring and classifying defects and calibration of 

equipment.

IV. PROCEDURES.

A. Determining Comparability. Whenever a previously inspected 

unreworked lot is reinspected, the following procedure shall be used to determine if the results of 

the two inspections are comparable (i.e., statistically the same) or whether they are 

noncomparable (i.e., statistically different). 

1. For each AQL involved in the reinspection, compare the number of defects

found on original inspection with the number of defects found on reinspection.

 a. If the number of defects found on original inspection is the same as the number of 

defects found on reinspection, the results are automatically considered comparable; proceed to 

paragraph V.B.

b. If the number of defects found on original inspection and the reinspection

are different, note which is smaller.

_______________

This Subsection supersedes Subsection 203.2, April 2010 *

* Denotes change
SUBSECTION 203.2

 DLA Troop Support 4155.6 *

2. Refer to Enclosure 1, Table I, Critical Values. Find the number in column A

that is the same as the smaller number of defects found during the original inspection or the 

reinspection. Then locate the number in column B which is on the same line as the number in 

column A.

3. Compare the larger number of defects found during the original inspection or

the reinspection to the number found in column B and determine whether or not the reinspection 

results are comparable to the original inspection results. Refer to 

Enclosure 2 for examples illustrating comparability determinations.

a. If the larger number of defects found is equal to or larger than the number 

found in column B, the results are noncomparable.

b. If the larger number of defects found is less than the number found in 

column B, the results are comparable.

B. Determining Product Conformance Based On Comparability Determinations.

Once comparability determinations have been made for AQL, it must be decided whether or not 

the lot is conforming or nonconforming.

 1. Based on the comparability determinations already made, determine for each AQL whether 

the original results or the reinspection results will be applicable for determining conformity (i.e., 

the applicable results are those used as the basis for determining conformity to contract 

requirements).

 a. If the reinspection results for AQL are comparable to the original inspection results, the 

original inspection results shall be applicable for determining conformity to contract 

requirements.

 b. If the reinspection results for an AQL are noncomparable to the original inspection 

results, the reinspection results shall be applicable for determining conformity to contract 

requirements. In this case the applicable results (i.e., the reinspection results) must be compared 

to the accept/reject criteria for the AQL involved. If the reinspection results are conforming, the 

lot is considered conforming for that AQL and vice-versa.

 2. Determine lot conformance based on comparability determinations of all AQLs.

a. If the applicable inspection results for all AQLs involved are conforming, the

lot is considered conforming to contract requirements.

 b. If the applicable inspection results of any of the AQLs involved are nonconforming, the 

lot is considered nonconforming to contract requirements.

V. EXCEPTION TO THE COMPARABILITY DETERMINATION PROCEDURES. 

When no AQL is specified and one or more defects is cause for rejection, comparability computations are 

not performed and the results of the reinspection shall be applicable for determining conformance.

VI. DISTRIBUTION OF REINSPECTION REPORTS. Results of reinspection of unreworked lots 

including determination of statistically different results, shall be reported in accordance with Subsection 

209.3.

VII. REPORTING ADDITIONAL INSPECTION COSTS. Costs incurred in reinspection of 

unreworked lots, when applicable, shall be reported as detailed in Subsection 231.1.
ENCLOSURE 1

SUBSECTION 203.2

 DLA Troop Support 4155.6 *

TABLE I – CRITICAL VALUES 1/

Column A Column B

0 3

1 5

2 7

3 9

4 11

5 12

6 14

7 15

8 17

9 18

 10 19

 11 21

 12 22

 13 23

 14 25

 15 26

 16 27

 17 28

 18 30

 19 31

 20 32

 21 34

 22 35

 23 36

 24 37

 25 39

 26 40

 27 41

 28 42
ENCLOSURE 1

SUBSECTION 203.2

DLA Troop Support 4155.6 * 

Table I – CRITICAL VALUES 1/

Column A Column B

 29 43

 30 45

 31 46

 32 47

 33 48

 34 49

 35 51

1/ Values in this Table are taken from Table I of Quality Control and Reliability 

Handbook H-109, Statistical Procedures for Determining Validity of Suppliers

Attributes Inspection, Office of the Assistant Secretary of Defense. 

The difference in usage of Table I of H-109 and Table I of this Subsection is 

that the former is for a one sided test whereas the latter is for a two sided test.
ENCLOSURE 2

SUBSECTION 203.2

 DLA Troop Support 4155.6

EXAMPLES ILLUSTRATING COMPARABILITY DETERMINATIONS

1. Situation #1 – Only one AQL is involved in the reinspection and the results are comparable.

 

 COL B#

 COL A # TO USE

 # DEFECTS FOUND (SMALLER ADJACENT TO RESULTS COMPARABLE APPLICABLE CONFORMING 

AQL ACC/REJ ORIG REINSP # OF DEFECTS) COL A# YES/NO REASON RESULTS FOR AQL

2.5 1 2 2 6 2 7 YES 1/ ORIG 2/ NO

2. Situation #2 – More than one AQL was involved in the reinspection; all reinspection results were found comparable.

COL B#

 COL A# TO USE 

 # DEFECTS FOUND (SMALLER # ADJACENT TO RESULTS COMPARABLE APPLICABLE CONFORMING

AQL ACC/REJ ORIG REINSP # OF DEFECTS) COL A# YES/NO REASON RESULTS FOR AQL

2.5 2 3 5 8 5 12 YES 1/ ORIG 2/ NO

4.0 3 4 4 8 4 11 YES 1/ ORIG 2/ NO

10.0 7 8 8 6 6 14 YES 1/ ORIG 2/ NO

 

3. Situation #3 – More than one AQL is involved in the reinspection; the reinspection results for two AQLs were determined noncomparable

and the results for one AQL were determined comparable.

 COL B#

 COL #A TO USE

 # DEFECTS FOUND (SMALLER # ADJACENT TO RESULTS COMPARABLE APPLICABLE CONFORMING

AQL ACC/REJ ORIG REINSP # OF DEFECTS COL A# YES/NO REASON RESULTS FOR AQL

2.5 2 3 4 0 0 3 NO 3/ REINSP YES

4.0 3 4 10 10 10 19 YES 4/ ORIG NO

\10.0 7 8 8 17 8 17 NO 5/ REINSP NO
ENCLOSURE 2

SUBSECTION 203.2

DLA Troop Support 4155.6 *

1/ The larger number of defects found was less than the appropriate value in column B of Table I; the results are comparable and the 

original inspection results shall be used to determine contract compliance. The lot is considered nonconforming because the original 

results were used to determine contract compliance and those results were nonconforming.

2/ The applicable results are the original results because the inspection and reinspection results were considered comparable.

3/ The larger number of defects noted exceeded the appropriate value in column B of Table I; the reinspection results were 

noncomparable therefore the reinspection results were used to determine contract compliance for this AQL. The lot is considered 

conforming for this AQL.

4/ The reinspection results equal the original results; they are automatically considered comparable. The appropriate value from column 

B is shown for illustration only; it was not necessary to note it because the number of defects found on the two inspections were equal. 

The original results are applicable and the lot is nonconforming for that AQL. 

5/ The larger number of defects noted equal the appropriate value in column B; the results were noncomparable and the reinspection 

results shall be used to determine contract compliance for this AQL. The lot is considered nonconforming for this.