OCvar-class {AcceptanceSampling}

Class Family "OCvar".

Description

The family "OCvar" ("Operating Characteristic" function) of classes provides methods for creating, plotting, printing and assessing single acceptance sampling plans for variables, based on the Normal ("OCnormal") distribution.

Objects from the Class

The "OCvar" class is a virtual Class: No objects may be created from it.

However, objects from the derived classes can be created by calls of the form new("OCnormal", ...), for example, or preferably using the creator function OCvar.

Slots

n:

Object of class "numeric". A vector of length 1 giving the sample size.

k:

Object of class "numeric". A vector of length 1 giving the absolute distance, in units of the standard deviation, between the specification limit (based on the distribution of the items) and the acceptance limit (based on the distribution of the sample mean). See Schilling (1982) page 226 for details.

type:

Object of class "character". The possible types relate to the distribution on which the plans are based on. Currently the only supported distribution is normal.

pd:

Object of class "numeric". A numeric vector indicating the quality for which a probability of acceptance is calculated under the specified sampling plan. Meaning differs for the different types.

For "OCnormal" this relates to the proportion of defectives created by the process.

s:

Object of class "numeric". A vector of length 1 giving the population/sample standard deviation.

s.type:

Object of class "character". Only for class "OCnormal", indicates whether the plan is based on the population (s.type="known") or sample standard deviation (s.type="known").

paccept:

Object of class "numeric". A numeric vector with the probability of acceptance which correspond to the quality as given by pd.

Methods

plot

signature(x="OCnormal", y="missing"),
signature(x="numeric", y="OCnormal")

: Plot the OC curve.

show

signature("OCvar"): Show the details of the sampling plan.

summary

signature("OCcar"): Summarise the sampling plan. Optional argument full (defaults to FALSE) will show the details at all quality values (pd) supplied when the object was created.

assess

signature(object="OCvar"): Assess whether the sampling plan can meet the specified Producer Risk Point (PRP) and/or Consumer Risk Point (CRP). For details see assess,OCvar-method

Author(s)

Andreas Kiermeier

References

Guenther, W. C. (1977) Sampling Inspection in statistical quality control, Charles Griffin and Company Limited

Hald, A. (1981), Statistical theory of sampling inspection by attributes, Academic Press.

Schilling, E. G. (1982), Acceptance Sampling in Quality Control, Dekker

See Also

OCvar