cg_ToleranceChart: cg_ToleranceChart

Description

Function visualize the given values of measurement in a Tolerance View.

Usage

cg_ToleranceChart(
  x,
  target,
  tolerance,
  ref.interval,
  facCg,
  facCgk,
  n = 0.2,
  col,
  pch,
  xlim,
  ylim,
  main,
  conf.level = 0.95,
  cgOut = TRUE
)

Value

The function cg_ToleranceChart returns a list of numeric values. The first element contains the calculated centralized gage potential index Cg and the second contains the non-centralized gage capability index Cgk.

Arguments

x: A vector containing the measured values.
target: A numeric value giving the expected target value for the x-values.
tolerance: Vector of length 2 giving the lower and upper specification limits.
ref.interval: Numeric value giving the confidence interval on which the calculation is based. By default it is based on 6 sigma methodology. Regarding the normal distribution this relates to pnorm(3) - pnorm(-3) which is exactly 99.73002 percent. If the calculation is based on another sigma value ref.interval needs to be adjusted. To give an example: If the sigma-level is given by 5.15 the ref.interval relates to pnorm(5.15/2)-pnorm(-5.15/2) which is exactly 0.989976 percent.
facCg: Numeric value as a factor for the calculation of the gage potential index. The default value for facCg is 0.2.
facCgk: Numeric value as a factor for the calculation of the gage capability index. The default value for facCgk is 0.1.
n: Numeric value between 0 and 1 giving the percentage of the tolerance field (values between the upper and lower specification limits given by tolerance) where the values of x should be positioned. Limit lines will be drawn. Default value is 0.2.
col: Character or numeric value specifying the color of the line and points in the tolerance view. Default is `black`.
pch: Numeric or character specifying the plotting symbol. Default is 19 (filled circle).
xlim: Numeric vector of length 2 specifying the limits for the x-axis. Default is NULL which means the limits are set automatically.
ylim: Numeric vector of length 2 specifying the limits for the y-axis. Default is NULL which means the limits are set automatically.
main: Character string specifying the title of the plot. Default is `Tolerance View`.
conf.level: Confidence level for internal t.test checking the significance of the bias between target and mean of x. The default value is 0.95.
cgOut: Logical value deciding whether the Cg and Cgk values should be plotted in a legend. Default is TRUE.

Details

The calculation of the potential and actual gage capability are based on the following formulae:

Cg = (facCg * tolerance[2]-tolerance[1])/ref.interval
Cgk = (facCgk * abs(target-mean(x))/(ref.interval/2)

If the usage of the historical process variation is preferred the values for the tolerance tolerance must be adjusted manually. That means in case of the 6 sigma methodology for example, that tolerance = 6 * sigma[process].

Examples

Run this code


x <- c(9.991, 10.013, 10.001, 10.007, 10.010, 10.013, 10.008,9.992,
       10.017, 10.005, 10.005, 10.002, 10.017, 10.005, 10.002, 9.996,
       10.011, 10.009, 10.006, 10.008, 10.003, 10.002, 10.006, 10.010, 10.013)

cg_ToleranceChart(x = x, target = 10.003, tolerance = c(9.903, 10.103))