Rejection number, sampling

CJJ., use first sampling plan below arrow f use first sampling plan above arrow Ac, acceptance number Re, rejection number. 

Notes Acc. = acceptance number Rej. = rejection number Cumul. = cumulative sample. 

If rejection number exceeded on the first sample, no second sample is taken. 

Action/reject numbers which relate batch size versus sample size versus AQL. 

The laboratory must observe and document the conditions that exist at the time of receipt and that may adversely impact on the integrity of a sample. Irregularities such as unsealed sample containers on receipt, samples without any identification code, mismatches between the sample number and the sample identification number on the form, inadequate sample volume/weight, unusual condition of the sample (e.g., color, odor, or hemolysis) should be noted. Instructions from competent authorities and/or clients may be required to decide whether the sample should be rejected, and in any case the abnormalities should be documented in the sample logbook for possible future reference. 

Rejected products are those which are lost after preparation including incompletely filled containers, samples for laboratory, breakage, failure from visual inspection et cetera. The gross yield minus the reject number gives the net yield. When the net yield of preparation, the number of packages or flie number... 

Single Sampling Plan. This type of sampling plan is used when the results of a single sample from an inspection lot are conclusive in determining its acceptability. The lot is accepted if the number of defectives found in the sample is equal to or less than the acceptance number AC or C. Similarly, the lot is rejected if the number of defectives found in the sample is equal to or greater than the rejection number RE or r. 

Multiple Sampling Plan. A multiple sampling plan is an extension of a double sampling plan. As long as the number of defectives falls between acceptance and rejections numbers, the inspection is continued. 

From the information regarding the inspection level, sample size code letter, sampling plan, and specified AQL value, determine the acceptance and rejection number. If the AQL value is unspecified, start with a 2.5 percent defective AQL value. 

Example. Given the following information, determine the sample size and acceptance and rejection numbers using (1) single and (2) double sampling plans. 

Using Table 16-3 (single sampling plan for normal inspection), we find that for code letter J and AQL of 1.0, the sample size is 80 with acceptance number AC = 2 and rejection number RE = 3. Thus, the course of action should be accept—if the number of defectives is 2 or less—or reject—if the number of defectives is 3 or more. 

The second sample size is 50 pieces and the acceptance number (for both samples) is AC = 3. The rejection number (for both samples) is RE = 4. The following procedure should be followed. 

Trial number and location and definition of specific crop fractions to be sampled had been a significant reason for study rejection prior to 1996. This particular guideline has helped resolve these issues in studies conducted since that time. 

Acceptance sampling can be either by attributes or by variables. In sampling by attributes, the item in the batch of product either conforms or not. The number of nonconformities in the batch is counted and if this reaches a predetermined figure, the batch is rejected. In sampling by variables, the characteristic of interest is measured on a continuous scale. If the average meets a predetermined value,... 

Normal, tightened or reduced inspection may be used. Tightened inspection is introduced when two out of five consecutive lots have to be rejected. This is normally kept in force until the inspector is satisfied that quality has been restored. If the quality is consistently better than the Acceptance Quality Limit (AQL), then reduced inspection can be introduced which requires two fifths of the number of samples taken for normal inspection. 

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