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Question using CRITBINOM
I have a Quality Control question using CRITBINOM().
My understanding is shown in cell(A7), but it does not seem right. Will someone help me, please? Sub Question_on_CRITBINOM() Range("A1") = "Data" Range("B1") = "Description" Range("A2") = 25 Range("A3") = 0.5 Range("A4") = 0.01 Range("B2") = "Number of Bernoulli trials" Range("B3") = "Probability of a success on each trial" Range("B4") = "Criterion value" Range("A6") = "=CRITBINOM(A2,A3,A4)" Range("A7") = "=""For a "" & (1-A4)*100 & ""% success rate, a maximum of rejects allowed is "" &A6 & "" out of "" & A2 & "" trials. If it is over that, reject the whole lot.""" End Sub |
#2
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You're getting the correct answer from CRITBINOM. Of course, your criterion
of 1% is very stringent. In effect, to use these arguments to CRITBINOM is to ask: Of 1000 lots, 10 of them (1%) have the 10 smallest number of defectives. I'm testing 25 units in each of my 1000 lots, and 50% of the units are defective in each lot. What is the largest number of defective units in the 10 lots that have the smallest number of defective units? With a 50% probability of a hit for each unit, it's very unusual (cum 1%) to get only 1, 2, 3, 4, 5, 6 or 7 hits out of 25 trials. To convince yourself that CRITBINOM returned the proper number, enter the numbers 1 through 25 in A1:A25. In B1, enter this formula: =BINOMDIST(A1,25,0.5,TRUE) and copy-and paste that down into B2:B25. You'll note that for 6 successes, BINOMDIST returns .007, and for 7 successes, BINOMDIST returns .02. This conforms to the CRITBINOM definition, "Returns the smallest value for which the cumulative binomial distribution is greater than or equal to a criterion value." 7 is the number of successes associated with your criterion value, ..01, which is the smallest number greater than .007 in the binomial distribution as you've defined it with your arguments. C^2 Conrad Carlberg "lashio" wrote in message ... I have a Quality Control question using CRITBINOM(). My understanding is shown in cell(A7), but it does not seem right. Will someone help me, please? Sub Question_on_CRITBINOM() Range("A1") = "Data" Range("B1") = "Description" Range("A2") = 25 Range("A3") = 0.5 Range("A4") = 0.01 Range("B2") = "Number of Bernoulli trials" Range("B3") = "Probability of a success on each trial" Range("B4") = "Criterion value" Range("A6") = "=CRITBINOM(A2,A3,A4)" Range("A7") = "=""For a "" & (1-A4)*100 & ""% success rate, a maximum of rejects allowed is "" &A6 & "" out of "" & A2 & "" trials. If it is over that, reject the whole lot.""" End Sub |
#3
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Hi, Conrad
Thank you very much for your detail explanation. I understand it better now. "Conrad Carlberg" wrote in message nk.net... You're getting the correct answer from CRITBINOM. Of course, your criterion of 1% is very stringent. In effect, to use these arguments to CRITBINOM is to ask: Of 1000 lots, 10 of them (1%) have the 10 smallest number of defectives. I'm testing 25 units in each of my 1000 lots, and 50% of the units are defective in each lot. What is the largest number of defective units in the 10 lots that have the smallest number of defective units? With a 50% probability of a hit for each unit, it's very unusual (cum 1%) to get only 1, 2, 3, 4, 5, 6 or 7 hits out of 25 trials. To convince yourself that CRITBINOM returned the proper number, enter the numbers 1 through 25 in A1:A25. In B1, enter this formula: =BINOMDIST(A1,25,0.5,TRUE) and copy-and paste that down into B2:B25. You'll note that for 6 successes, BINOMDIST returns .007, and for 7 successes, BINOMDIST returns .02. This conforms to the CRITBINOM definition, "Returns the smallest value for which the cumulative binomial distribution is greater than or equal to a criterion value." 7 is the number of successes associated with your criterion value, .01, which is the smallest number greater than .007 in the binomial distribution as you've defined it with your arguments. C^2 Conrad Carlberg "lashio" wrote in message ... I have a Quality Control question using CRITBINOM(). My understanding is shown in cell(A7), but it does not seem right. Will someone help me, please? Sub Question_on_CRITBINOM() Range("A1") = "Data" Range("B1") = "Description" Range("A2") = 25 Range("A3") = 0.5 Range("A4") = 0.01 Range("B2") = "Number of Bernoulli trials" Range("B3") = "Probability of a success on each trial" Range("B4") = "Criterion value" Range("A6") = "=CRITBINOM(A2,A3,A4)" Range("A7") = "=""For a "" & (1-A4)*100 & ""% success rate, a maximum of rejects allowed is "" &A6 & "" out of "" & A2 & "" trials. If it is over that, reject the whole lot.""" End Sub |
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