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Engineering Statistics Handbook Episode 8 Part 6

Tham khảo tài liệu 'engineering statistics handbook episode 8 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 6.2.4. What is Double Sampling 5.39 0 3 0.49 2.64 5.09 0 4 0.77 3.92 4.31 1 4 0.68 2.93 4.19 0 5 0.96 4.02 3.60 1 6 1.16 4.17 3.26 1 8 1.68 5.47 2.96 2 10 2.27 6.72 2.77 3 11 2.46 6.82 2.62 4 13 3.07 8.05 2.46 4 14 3.29 8.11 2.21 3 15 3.41 7.55 1.97 4 20 4.75 9.35 1.74 6 30 7.45 12.96 Example Example of a double sampling plan We wish to construct a double sampling plan according to P1 0.01 ex 0.05 P2 0.05 0.10 and n1 n2 The plans in the corresponding table are indexed on the ratio R P2 P1 5 We find the row whose R is closet to 5. This is the 5th row R 4.65 . This gives C1 2 and C2 4. The value of n is determined from either of the two columns labeled pn1. The left holds ex constant at 0.05 P 0.95 1 - Q and the right holds 3 constant at 0.10. P 0.10 . Then holding ex constant we findpn1 1.16 so n 1.16 p1 116. And holding constant we find pn1 5.39 so n 5.39 p2 108. Thus the desired sampling plan is n1 108 C1 2 n2 108 c2 4 If we opt for n2 2n1 and follow the same procedure using the appropriate table the plan is n1 77 C1 1 n2 154 C2 4 The first plan needs less samples if the number of defectives in sample 1 is greater than 2 while the second plan needs less samples if the number of defectives in sample 1 is less than 2. ASN Curve for a Double Sampling Plan http www.itl.nist.gov div898 handbook pmc section2 pmc24.htm 3 of 5 5 1 2006 10 34 47 AM 6.2.4. What is Double Sampling Construction Since when using a double sampling plan the sample size depends on whether of the ASN or not a second sample is required an important consideration for this kind of curve sampling is the Average Sample Number ASN curve. This curve plots the ASN versusp the true fraction defective in an incoming lot. We will illustrate how to calculate the ASN curve with an example. Consider a double-sampling plan n1 50 c1 2 n2 100 C2 6 where n1 is the sample size for plan 1 with accept number C1 and n2 c2 are the sample size and accept number respectively for plan 2. Let p .06. Then the probability of