48 BELL SYSTEM TECHNICAL JOURNAL 



merit boxes or when the gage or testing device provides for automatic count 

 Regardless of what method of counting is used there should be agreement 

 between the size of sample selected and sample size indicated in the sampling 

 table. 



2.3 Reins pection of Rejected Lots 



In order to guarantee the protection promised by a particular Double 

 Sampling Plan it is required that a rejected lot be completely cleared of all 

 defects. The rejected material should be repaired and returned for rein- 

 spection as one lot. It should then be reinspected for all inspection items 

 using the sample size that would normally apply to a new lot of the same 

 size. If a defect is found during reinspection it is evident that proper re- 

 pair or sorting has not been accomplished. Such a lot should, of course, 

 not be considered acceptable until all defects are removed. 



In the Lot-by-Lot Record, the results of resampling of rejected lots are 

 recorded on a separate line and the entry circled or otherwise identified so 

 that it will not be included with the results of first samples on the Summary 

 Form. 



3. Supervision of the Double Sampling Plan 



In order that maximum advantage may be gained from the use of Double 

 Sampling Lot Inspection it is necessary that attention be given to the topics 

 listed below. Upon proper attention to these factors depends the effective- 

 ness of the Plan. 



3.1 Changes in AOQL 



There is no assurance that the value originally selected for an AOQL will 

 continue to be the most satisfactory in view of changing factors relating to 

 the product, such as: 



3.11 Changes in design of the product or changes in the requirements for 

 inspection items may increase or decrease the trouble caused by the ac- 

 ceptance of defective parts and therefore will occasion a review of the 

 AOQL value. 



3.12 New methods of manufacture that change the difficulty and there- 

 fore the cost of making a product will necessitate a reconsideration of the 

 AOQL value. 



3.13 An excessive number of complaints or other reports of difficulty 

 from succeeding stages of manufacture or from customers may indicate 

 too large an AOQL. 



3.14 If no significant changes such as those mentioned above exist and 

 there are repeated lot rejections, it would appear that quality is unsatis- 



