Ken Larson of the AT&T Company developed the binomial nomograph. The nomograph greatly simplifies and reduces the computational burden involved with. Answer to Use the binomial nomograph to nd a single-sampling plan fro which p1 = , = , p2 = and = Suppose the l. OC Curve Calculation by Binomial. Distribution. Note that we cannot always use the binomial distribution because. •. B inomials are based on constant.

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The part is classified as good or defective.

The manufacturing department, as part of the process or quality control program, may also use sampling techniques. Random spot-checking may sometimes be used when a process is in statistical control.

The unscientific sampling technique, known as the constant percentage sample, is a very popular procedure.

US3685724A – Device for the graphical solution of simultaneous equations – Google Patents

The semi vertical lines on the nomograph represent the sample sizes and the semi horizontal lines are the acceptance numbers. The device illustrated in Nomogra;h. For this example, the differences increase slightly as the curve approaches the tail. Two parameters are specified in a continuous sampling plan.

USA – Device for the graphical solution of simultaneous equations – Google Patents

Accepted and screened rejected lots are sent to their destination. It is also used to approximate the binomial probabilities involving the number of defective parts when the sample n is large and p is very small.

A trial-and-error method using tables has been given, but this is somewhat tedious to apply and is limited by the fact that the tables only apply for lot sizes no greater than with some scattered exceptions. The opposite ends of sticks 16, 18, are both bifurcated, as shown at 24, 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. The intermediate portion of string 40 passes around a further pin 44 movable along vertical scale As the number of quality characteristics being checked increases, the effectiveness of the inspector decreases. The six methods listed below are widely used. To assist in the task, a tool called an L will be used.

They may be determined by your customer, special studies, or past experience. The curved lines in the body of the chart represent binomia cumulative number of occurrences or successes that are of interest.

Simultaneous solution of the cumulative blnomial equations 1 and 2 for n and c will yield the required plan. If the number of defects or defectives in the first sample do not exceed c 1the lot is accepted and a second sample is not taken. Sampling at the end of a manufacturing process provides a check on the adequacy of the quality control procedures of the manufacturing department.

The binomial is used extensively in the construction of sampling plans. The computing device of the nomographic principle, in particular for price calculation weighed amounts. Also a straight line can be dropped from R to the pn scale. The Inspection organization or end of the line appraisal function has three objectives that will be achieved in part through sampling techniques.

During this movement of pin 44, tension is maintained in the nnomograph, e.

A device as defined in claim 1, which device is used for the graphical solution of Larson”s Nomograph of cumulative binomial distributions for designing single-stage attribute plans for individual small lots, the C-family of curves representing the number of occurrences, the K-family of curves representing the number of trials or sample size, said first vertical axis including scale markings representing the probability of C-occurrence or fewer occurrences in K-trials, and said second vertical axis includes scale markings representing the probability of occurrence in a single trial.


The probability of acceptance is the probability that the number of defects or defective units in the sample is equal to or less than the acceptance number of the sampling plan. No checking may be warranted when the process capability is known and the probability of defective product is very small. Two sample sizes n 1n 2 and two acceptance numbers c 1c 2 or AN 1AN 2 are specified.

The inspection accuracy is not achieved for small lots and too much time and effort may be spent on large lots. In some cases, there may be minor variations between the two methods. This type of sampling may be used when a supplier has been certified as providing excellent onmograph products over some length of time or the process capability is so good that other methods of inspection are not necessary. The AOQ and OC curve, when used together, describe the characteristics of the sampling plan and the risks involved.

These points are shown in FIG. When inspection is performed by attributes, product is classified as good or defective four types of acceptance sampling plans may be used, with lot by lot single sampling plans being the binomail popular. The L may be modified for any value of b. The process capability must be known and the chance of defective products arriving at the inspection point must be very small.

Many variations, modifications, and other applications of the illustrated embodiments will be apparent. Also, the sampling risks involved are not known. Like the binomial nomograph, it may also be used to determine sample sizes and acceptance numbers for sampling plan applications.

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