Minitab Sampling

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    ME TO 17

    T 17 (Acceptance Sampling) .

    . Stat > Quality Tools > Acceptance Sampling by Attributes,

    . Stat > Quality Tools > Acceptance Sampling by Variables.

    .

    (Help)

    , Help > Methods and Formulas > Quality and process

    improve-ment > Acceptance Sampling.

    .

    Stat > Quality Tools > Acceptance Sampling by Attributes / , .

    , Create a sampling plan, (n, c) , Compare user defined sampling plans, .

    .1. Create a sampling plan -

    Measurement type Go/no go (defectives) (units) , Number of defects .

    Units for quality levels :

    Go/no go (defectives), Percent defective (0-100), Proportion defective (0-1), Defectives per million (0-1.000.000).

    Number of defects, Defects per unit, Defects per hundred, Defects per million.

    Acceptable quality level (AQL) AQL. H AQL Units for quality levels.

    Rejectable quality level (RQL or LTPD) RQL LTPD. AQL < LTPD. LTPD Units for quality levels.

    Producer's risk (Alpha) o (0-1).

    Consumer's risk (Beta) o (0-1). 1 > .

    Lot Size . (AOQ), (), Options.

    .2. Compare user defined sampling plans -

    Measurement type, Units for quality levels, Acceptable quality level (AQL), Rejectable quality level (RQL or LTPD) Lot Size, .1. ,

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    Acceptable quality level (AQL) Rejectable quality level (RQL or LTPD) . Sample sizes Acceptance numbers.

    Sample sizes , Acceptance numbers .

    (n) (c1, c2, , cr),

    (c) (n1, n2, , nr),

    (n1, n2, , nr) (c1, c2, , cr), (n1, c1), (n2, c2), , (nr, cr).

    . Go/no go (defectives). (Lot Size) Use hypergeometric distribution for isolated lot Options. , Number of defects, Poisson.

    B.

    Stat > Quality Tools > Acceptance Sampling by Variables > Create/Compare / , . , Create a sampling plan, (n, k) , Compare user defined sampling plans .

    Stat > Quality Tools > Acceptance Sampling by Variables > Accept/Reject Lot .

    B.1. Create a sampling plan -

    Units for quality levels, Acceptable quality level (AQL), Rejectable quality level (RQL or LTPD), Producer's risk (Alpha), Consumer's risk (Beta) Lot Size, . Lower spec, Upper spec Historical standard deviation (Optional).

    Lower spec Upper spec , ( ). ,

    Historical standard deviation (Optional) , .

    .2. Compare user defined sampling plans -

    Units for quality levels, Acceptable quality level (AQL), Rejectable quality level (RQL or LTPD), Sample sizes, Lower spec, Upper spec, Historical standard deviation (Optional), Lot Size . Acceptable quality level (AQL) Rejectable quality level (RQL or LTPD) .

    Critical distances (k values) . Sample sizes :

    (n) (k1, k2, , kr),

    (k) (n1, n2, , nr),

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    (n1, n2, , nr) (k1, k2, , kr) (n1, k1), (n2, k2), , (nr, kr).

    .3. Accept/Reject Lot

    Stat > Quality Tools > Acceptance Sampling by Variables > Accept/Reject . Measurement data . Critical distance (k values), Lower spec, Upper spec Historical standard deviation (Optional) .

    1

    N = 500. 90% 1% , 95% 4% .

    () (n,c) .

    () , Q-po -po. (AOQL);

    () 2% 4% :

    (i) n () c=2, c=3, c=4.

    (ii) c () n=177, n=227, n=277.

    ;

    () (n,c)

    (i) ,

    (ii) Poisson.

    (i) (ii).

    : () , p1=AQL=1%, p2=LTPD=4%, =0.10 =0.05. Stat > Quality ols > Acceptance Sampling by Attributes

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    o MINITAB session window

    Acceptance Sampling by Attributes

    Measurement type: Go/no go

    Lot quality in percent defective

    Use binomial distribution to calculate probability of acceptance

    Acceptable Quality Level (AQL) 1

    Producers Risk () 0,1

    Rejectable Quality Level (RQL or LTPD) 4

    Consumers Risk () 0,05

    Generated Plan(s)

    Sample Size 227

    Acceptance Number 4

    Accept lot if defective items in 227 sampled 4; Otherwise reject.

    Percent Probability Probability

    Defective Accepting Rejecting

    1 0,921 0,079

    4 0,049 0,951

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    - n=227 c=4. 0.079 0.049 ( ). session window .

    ( ).

    () () 500 Lot size ( )

    session window () :

    (i) (Q ATI),

    (ii) AOQL=0.612% 1.599%.

    Acceptance Sampling by Attributes

    . . . . . . . . . . . . . . . . . . . . . . . .

    Percent Probability Probability

    Defective Accepting Rejecting AOQ ATI

    1 0,921 0,079 0,503 248,6

    4 0,049 0,951 0,107 486,6

    Average outgoing quality limit (AOQL) = 0,612 at 1,599 percent defective.

    Q-po -po.

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    (-i) Stat > Quality Tools > Acceptance Sampling by Attributes ( Options).

    o MINITAB session window

    Acceptance Sampling by Attributes

    Measurement type: Go/no go

    Lot quality in percent defective

    Use binomial distribution to calculate probability of acceptance

    Acceptable Quality Level (AQL) 1

    Rejectable Quality Level (RQL or LTPD) 4

    Compare User Defined Plan(s)

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    Sample Acceptance Percent Probability Probability

    Size(n) Number(c) Defective Accepting Rejecting

    227 2 1 0,604 0,396

    227 2 2 0,166 0,834

    227 2 4 0,005 0,995

    227 3 1 0,806 0,194

    227 3 2 0,333 0,667

    227 3 4 0,018 0,982

    227 4 1 0,921 0,079

    227 4 2 0,523 0,477

    227 4 4 0,049 0,951

    Accept lot if defective items in n sampled c; Otherwise reject.

    ( ).

    session window. , n=227 c=3, p0=0.02 0.333. c, .

    (-ii) Stat > Quality Tools > Acceptance Sampling by Attributes ( Options)

    o MINITAB session window

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    Acceptance Sampling by Attributes

    Measurement type: Go/no go

    Lot quality in percent defective

    Use binomial distribution to calculate probability of acceptance

    Acceptable Quality Level (AQL) 1

    Rejectable Quality Level (RQL or LTPD) 4

    Compare User Defined Plan(s)

    Sample Acceptance Percent Probability Probability

    Size(n) Number(c) Defective Accepting Rejecting

    177 4 1 0,967 0,033

    177 4 2 0,719 0,281

    177 4 4 0,160 0,840

    227 4 1 0,921 0,079

    227 4 2 0,523 0,477

    227 4 4 0,049 0,951

    277 4 1 0,853 0,147

    277 4 2 0,349 0,651

    277 4 4 0,013 0,987

    Accept lot if defective items in n sampled c; Otherwise reject.

    session window. , n=277 c=4, p0=0.02 0.349. n, .

    (-i) (), Options Use hypergeometric distribution for isolated lot. o MINITAB session window

    Acceptance Sampling by Attributes

    Measurement type: Go/no go

    Lot quality in percent defective

    Lot size: 500

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    Use hypergeometric distribution to calculate probability of acceptance

    Acceptable Quality Level (AQL) 1

    Producers Risk () 0,1

    Rejectable Quality Level (RQL or LTPD) 4

    Consumers Risk () 0,05

    Generated Plan(s)

    Sample Size 171

    Acceptance Number 3

    Accept lot if defective items in 171 sampled 3; Otherwise reject.

    Percent Probability Probability

    Defective Accepting Rejecting AOQ ATI

    1 0,951 0,049 0,626 187,1

    4 0,048 0,952 0,127 484,1

    Average outgoing quality limit (AOQL) = 0,763 at 1,600 percent defective.

    n=171 c=3. session window .

    (-ii) Stat > Quality Tools > Acceptance Sampling by Attributes

    o MINITAB session window

    Acceptance Sampling by Attributes

    Measurement type: Number of defe