HRN ISO , Larson nomogram, operating characteristic curve of the acceptance plan, statistical quality control attribute acceptance plans, sampling. Fortunately, Larson has determined a nomograph (a graphical calculating Larson’s nomograph can be used as follows: the vertical line on the left-hand side is. From the Larson nomogram, the binomial plan satisfying these specifications is n1⁄, c1⁄ Using the Lieberman and Owen () tables for D1 1⁄(20).

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It is also alrson to approximate the binomial probabilities involving the number of defective parts when the sample n is large and p is very small. At this time, one out of X shall be inspected. The decision is based on the specified criteria and the amount of defects or defective units found in the sample.

The AOQL is approximately. The value of pn is 2. Retrieved from ” https: The unscientific sampling technique, known as the constant percentage sample, lsrson a very popular procedure. The first is the frequency of checking f and the second is the clearing number i.

Larson Nomogram

Accepted and screened rejected lots are sent to their destination. Two parameters are specified in a continuous sampling plan.

If the number of defects or defectives in the first sample exceed c 2the lot is rejected and a second sample is not taken. The following other wikis use this file: There are some minor differences.

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They will be provided separately if you have the computer based version of QReview. This screenshot either does not contain copyright-eligible parts or visuals of copyrighted software, or the author has released it under a free license which should be indicated beneath this noticeand as such follows the licensing guidelines for screenshots of Wikimedia Commons. This is called sampling without replacement.

Summary [ edit ] Description Larson. Sampling plans will be constructed using both the binomial nomograph and the Thorndike chart.

The Thorndike chart, which will be discussed later, is a valuable aid in the construction of sampling plans using the Poisson distribution. The Poisson formula,is used to compute the probabilities of acceptance. The product may be grouped into lots or may be single pieces from a continuous operation.

Larsin best fitting acceptance number curve is the one to select. In the construction of a lot by lot single sampling plan, four parameters must be determined prior to determining the sample size and acceptance number.

The sampling will continue until a defect is found.

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The sampling risks are not known, so this method will not guarantee that the outgoing quality will be at an acceptable level. At the corner of the L where the value is 1, drop a straight line to the pn scale on the abscissa of the Thorndike chart.


The intersection will yield the sample size and acceptance number. A sample is selected and checked for various characteristics. The letter n represents the sample size. The sample larwon is determined as follows: A chart like the one shown noogramm is specified for various sequential sampling plans. The ordinate is the probability of c or fewer occurrences.

Draw a line from the AQL. A quality report is issued and the manufacturing organization will determine what action is to be taken if the material is not acceptable. Accepted lots and screened rejected lots are sent to their destination.


For products grouped into lots, the entire lot karson accepted or rejected. The values for the operating characteristic OC curve are obtained directly from the nomograph. Accepting or rejecting a lot is analogous to not rejecting or rejecting the null hypothesis in a hypothesis test.

A periodic audit to verify that conditions have not changed is a recommended practice when products are not checked on a routine basis.