Monday, May 13, 2019

ACCEPTANCE SAMPLING TECHNIQUE


·         ACCEPTANCE SAMPLING TECHNIQUE
 STATISTICAL QUALITY CONTROL
OPERATION MGMT
·         ACCEPTANCE SAMPLING TECHNIQUE
1.       USEFUL WHEN 100% INSPECTION IS NOT PRACTICAL
2.       ACCEPTANCE SAMPLING IS THE BEST WAY OF ESTIMATING THE QUALITY OF INCOMING OR OUTGOING LOTS
3.       RANDOM SAMPLING PROVIDES EACH ELEMENT  WITH AN EQUAL OF BEING SELECTED AND ALLOWS LOGICAL INTERPRETATION TO BE MADE ABOUT THE LOT.
     ACCEPTANCE SAMPLING INSPECTION :
1.       SAMPLING                                                                                                                                                BYATTRIBUTES
2.       SAMPLING BY VARIABLES
     APPLICATION OF ACCEPTANCE SAMPLING
1.       TESTING IS DESTRUCTIVE
2.       COST OF INSPECTION OF WHOLE LOT IS VERY HIGH
3.       INSPECTION OF WHOLE LOT IS NOT POSSIBLE
4.       WHEN INSPECTION ERROR RATE IS SO HIGH THAT 100% INSPECTION MIGHT PASS A HIGHER PERCENTAGE OF DEFECTIVE UNITS AS COMPARED TO SAMPLING PLANS
     ACCEPTANCE SAMPLING BY ATTRIBUTE
     INVOLVES EXTRACTING A RANDOM SAMPLE FROM THE LOT TO DETERMINE WHETHER TO ACCEPT OR REJECT THE ENTIRE LOT ON THE BASIS OF THE SAMPLE OR SEPARATE THE GOOD FROM THE BAD
     THIS PROCESS MAY BE USED :
1.       INWARD GOODS
2.       RECEIVING INSPECTION
3.       OR COMPONENTS
4.       IN PROCESS OF INSPECTION FOR SEMI FINSHED GOODS
5.       FINISHED PRODUCT
     ACCEPTANCE SAMPLING BY ATTRIBUTE
     THE SAMPLE MAY BE :
1.       SINGLE SAMPLE PLAN: A SINGLE SAMPLE OUT OF SPECIFIED LOT IS TAKEN. ALL THE ITEMS OF THE SAMPLE ARE PHYSICALLY INSPECTED AND DEFECTIVES ARE NOTED DOWN AND IT IS COMPARED WITH TOLERANCE LIMIT. IF DEFECTIVES ARE UP TO TOLERANCE LIMIT THE LOT IS ACCEPTED AND OTHERWISE REJECTED.
2.       DOUBLE SAMPLING PLAN:-TWO POSSIBILITIES EITHER ACCEPT OR REJECT. IF THE RESULT OF SINGLE SAMPLE IS INCONCLUSIVE THEN A SECOND SAMPLE IS DRAWN. THE RESULT OF SECOND SAMPLE IS COMBINED WITH SECOND SAMPLE TO REACH A FINAL DECISION

3.       SEQUENTIAL SAMPLING :-
1.       UNITS ARE RANDOMLY SELECTED FROM THE LOT
2.       TESTED ONE BY ONE
3.       AFTER EACH ONE IS TESTED A REJECT ,ACCEPT OR CONTINUOUS SAMPLING DECISION IS TAKEN, THIS PROCESS CONTINUES UNTIL THE LOT IS ACCEPTED OR REJECTED
      IMPORTANT CONCEPT OF ACCEPTANCE SAMPLING BY ATTRIBUTE
1.       AVERAGE OUTGOING QUALITY CURVES
2.       OPERATING CHARACTERISTICS CURVES
     AVERAGE OUTGOING QUALITY CURVES
     ACCEPTANCE SAMPLING PLANS PROVIDE MANAGERS WITH THE ASSURANCE THAT THE AVERAGE QUALITY LEVEL OR PERCENT DEFECTIVE ACTUALLY GOING TO CUSTOMER WILL NOT EXCEED A CERTAIN LIMIT

     OPERATING CHARACTERSTICS (OC) CURVES
     WHEN WE GO FOR ACCEPTANCE SAMPLING PLANS
1.       WE ACCEPT GOOD LOTS
2.       WE REJECT BAD LOTS
3.       WE MAY ACCEPT BAD LOTS
4.       WE MAY REJECT GOOD LOTS
§  WHEN A GOOD LOT IS REJECTED THE ERROR IS KNOWN AS TYPE ONE ERROR AND THE RISK OF REJECTING A GOOD LOT BASED ON SAMPLE EVIDENCE IS KNOWN AS PRODUCER’S RISK
     WHEN A BAD LOT IS ACCEPTED AS GOOD LOT BASED ON SAMPLE EVIDENCE THE ERROR IS KNOWN AS TYPE TWO ERROR. ALSO KNOWN AS CONSUMER’S RISK
     THE OPERATING CHARACTERISTICS CURVE DESCRIBES AN IMPORTANT FEATURE OF ACCEPTANCE SAMPLING PLAN. IT SHOWS HOW WELL AN ACCEPTANCE SAMPLING PLAN DISCRIMINATES BETWEEN GOOD OR BAD
     OPERATING CHARACTERISTICS CURVE
     D


1.       WE DEFINE A BAD LOT AS ANY HAVING 5% OR MORE DEFECTIVE IS KNOWN AS LOT TOLERANCE PERCENT DEFECTIVE
2.       THE PROBABILITY OF ACCEPTING A LOT WITH 5% DEFECTIVE SHOULD BE AS LOW AS POSSIBLE 10% THAT IS CALLED THE CONSUMER RISK. BUT THE PROBABILITY OF REJECTING A LOT WITH 5% DEFECTIVE OR MORE IS 90%



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