regulation 2(2)
SCHEDULE
regulation 23A
“SCHEDULE 2STATISTICAL SAMPLING METHODS
Inspection procedures
1.—(1) The inspector shall use, at his election, one of the two inspection methods described in sub-paragraphs (2), (3) and (4) below.
(2) The inspection methods referred to in sub-paragraph (1) above are a single submission scheme (“method A”) and a multiple submission scheme (“method B”). In the case of each method, the check to be carried out by the inspector shall consist of determining the number of defective measures in the sample taken by him.
(3) Where the inspector elects to use method A, he shall apply, for the purpose of accepting or rejecting the lot submitted, a sampling plan having the following characteristics, that is to say—
a standard quality level (SQL) between 0.40 and 0.90 per cent; and
a limiting quality level (LQ5) between 4.0 and 6.5 per cent.
The following are examples of sampling plans—
Single sampling plan
Sample size number Acceptance number Rejection number LQ5 SQL a 80 1 2 5.8 0.44 b 125 2 3 5.0 0.65 Double sampling plan
Sample size Total size Acceptance number Rejection number LQ5 SQL a First 50 50 0 2 Sample 5.8 0.44 Second 50 100 1 2 Sample b First 80 80 0 3 Sample 5.0 0.65 Second 80 160 3 4 Sample Where the inspector rejects a lot, he may, if he considers it appropriate to do so and the person submitting it so agrees, inspect each measure of length comprised in the lot and pass, or refuse to pass, as appropriate, each such measure as fit for use for trade in accordance with regulation 25 of these Regulations.
(4) Where the inspector elects to use method B, he shall apply, for the purpose of accepting or rejecting the lot submitted, sampling plans in accordance with the table below—
Sampling plans
| Order of submission | Sample size | Acceptance number | Rejection number |
|---|---|---|---|
| 1 | 70 | 0 | 1 |
| 2 | 85 | 0 | 1 |
| 3 | 105 | 0 | 1 |
| 4 | 120 | 0 | 1 |
Where the inspector has accepted a lot, he shall test the next lot to be submitted to him in accordance with the parameters applicable to “Order of submission 1” in the above sampling plans.
Where the inspector has rejected a lot (and accordingly not passed the measures of length comprised in it as fit for use for trade), the person submitting it to the inspector may submit to him for inspection either the same or another lot. The inspector shall then inspect the lot submitted to him in accordance with the parameters of the line of the above sampling plans immediately below the one applied by the inspector to the lot rejected by him immediately before. If the inspector does not accept the lot after inspecting it in accordance with the parameters applicable to “Order of submission 4” in the above sampling plans, he shall, if the person submitting it so agrees, inspect each measure of length comprised in the lot.
Interpretation
2. In this Schedule—
“acceptance number”, in relation to a statistical check by attributes, means the greatest number of defective measures found in the sample which, if attained, will nevertheless result in the acceptance of the lot being inspected;
“double sampling plan” means a sampling plan, an example of which is given in paragraph 1(3) above, under which the number of individual measures of length inspected is to be equal to the size of the first sample as specified by the plan and which entails the application of the following methodology. Where the number of defective measures found in the first sample is less than or equal to the first acceptance number, the lot is to be accepted. Where the number of defective measures found in the first sample is equal to or greater than the first rejection number, the lot is to be rejected. Where the number of defective measures found in the first sample falls between the first acceptance number and the first rejection number, a second sample, the size of which is specified by the plan, is to be inspected. Where the sum of the number of defective measures found in the first and second samples is less than or equal to the second acceptance number, the lot is to be accepted. Where such sum is greater than or equal to the second rejection number, the lot is to be rejected;
“limiting quality level (LQ5)” means the quality level of the lot submitted which corresponds in a sampling plan to a 95 per cent probability of acceptance;
“lot” means a group of measures of length, the number of which does not exceed 10,000 and which are of the same pattern, belong to the same precision class and are manufactured by the same process, and “size of the lot” means the number of measures of length comprised in the lot;
“rejection number”, in relation to a statistical check by attributes, means the number of defective measures of length found in the sample inspected which, if equalled or exceeded, will result in the rejection of the lot being inspected;
“sample” means a number of measures of length selected at random from a lot, and “sample size” means the number of measures of length in a sample;
“single sampling plan” means a sampling plan, an example of which is given in paragraph 1(3) above, under which the number of individual measures of length is to be equal to the size of the sample as specified by the plan and which entails the application of the following methodology. Where the number of defective measures found in the sample is less than or equal to the acceptance number, the lot is to be accepted. Where the number of defective measures is greater than or equal to the rejection number, the lot is to be rejected;
“standard quality level (SQL)” means the quality level of the lot submitted which corresponds in a sampling plan to a 95 per cent probability of acceptance; and
“statistical check by attributes” means an inspection in which the measures of length in a sample are classed as defective or not defective in accordance with the provisions of these Regulations.”