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R: Calculation of LTPD plan for sampling inspection by variables

planLTPD

R Documentation

Calculation of LTPD plan for sampling inspection by variables

Description

Calculation of LTPD plan (sample size n and critical value k) for sampling inspection by variables

Usage

planLTPD(N, pt, pbar, b = 0.1, cm = 1,method = c("exact", "napprox","ewma2","ewmaSK" ),
intdif = 20,lam=1)

Arguments

`N`	lot size (number of items in the lot)
`pt`	lot tolerance fraction defective
`pbar`	process average fraction defective
`b`	probability of accepting a lot of tolerance quality `pt` (consumer risk), default value 0.1
`cm`	parameter used in cost function of plans (see `Ims`) and defined as cost of inspection of one item by variables divided by cost of inspection of the item by attributes, default value 1
`method`	type of `OC` (operating characteristic) used, either `"exact"` (default) using non-central t-distribution, or `"napprox"` for approximate OC; if EWMA statistic is to be used, `"ewmaSK"` stands for the sigma known case, `"ewma2"` stands for the sigma unknown case
`intdif`	parameter used in finding n when `method` other than `"napprox"`, controlling the width of interval to be searched in for sampling plan optimal w.r.t. cost, difference from interval centre (n resulting from `planLTPD(..., method = "napprox"`) to lower or upper bound, default value 20
`lam`	smoothing parameter in case that EWMA statistic is used

Value

An instance of ACSPlan-class, with sample size in slot n and critical value in slot k.

References

Klufa, J.: Exact calculation of the Dodge-Romig LTPD single sampling plans for inspection by variables. Statistical Papers, Springer, Vol. 51(2), pages 297-305, 2010.

Examples

# find LTPD plan
planLTPD(N=1000,pt=0.1,pbar=0.001);
planLTPD(1000, 0.01,0.001,cm=1.5,b=0.1,method="ewmaSK",lam=0.9,intdif=60);
planLTPD(1000, 0.01,0.001,cm=1.5,b=0.1,method="ewma2",lam=0.9);

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

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> library(LTPDvar)
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/LTPDvar/planLTPD.Rd_%03d_medium.png", width=480, height=480)
> ### Name: planLTPD
> ### Title: Calculation of LTPD plan for sampling inspection by variables
> ### Aliases: planLTPD
> ### Keywords: misc
> 
> ### ** Examples
> 
> # find LTPD plan
> planLTPD(N=1000,pt=0.1,pbar=0.001);
An object of class "ACSPlan"
Slot "n":
[1] 16

Slot "k":
[1] 1.841766

Warning message:
In pt(q = k * n^0.5, df = n - 1, ncp = qnorm(1 - p) * n^0.5) :
  full precision may not have been achieved in 'pnt{final}'
> planLTPD(1000, 0.01,0.001,cm=1.5,b=0.1,method="ewmaSK",lam=0.9,intdif=60);
An object of class "ACSPlan"
Slot "n":
[1] 20

Slot "k":
[1] 2.585554

> planLTPD(1000, 0.01,0.001,cm=1.5,b=0.1,method="ewma2",lam=0.9);
An object of class "ACSPlan"
Slot "n":
[1] 75

Slot "k":
[1] 2.643843

> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>