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Owning Palette: Control Charts VIs

Installed With: Statistical Process Control Toolkit

Computes points and limits for an np chart, a control chart for number non-conforming. Optionally, you can choose a range of indices of samples to use and indices of samples to ignore in the control calculation. The actual number of samples the VI uses to calculate the control limits is also output. By default, control limits are calculated from the input samples. You can also calculate control limits from standard values by wiring the chart limit src input.

Details  

	chart limit src specifies whether or not to use standard values for the chart limit calculations. If unwired this defaults to the most common case where the chart limits are calculated from the data in the input array. You do not have to wire this cluster unless you want the chart limits to be calculated from standard values. When using standard values, the center line for the control chart, np-bar, is set to n*p0. source selects one of two sources for chart limits calculation: 0 from data—(Default) chart limits are calculated from the data in the input arrays as qualified by the index spec and indices to ignore inputs. 1 use std p0—chart limits are calculated from the standard value p0. std p0 is the standard p0 value to use when calculating chart limits from standard values. The center line for the control chart n*p-bar will then be set to n*p0.
	r:# units non-conforming/sample unit is the number of units non-conforming per sample inspected.
	n: sample size is the number of units in each sample.
	std error multiplier (3) is the multiplier to use for the upper and lower control limits. Normally you leave std error multiplier unwired, and the VI sets the control chart limits to ±3.0 standard errors. The default is 3.0.
	index spec is used to choose a range of samples in c to use for the control limit calculation. If you do not wire this cluster, all elements in c input array are included in the control limit calculation. start index is the index of the first element of c to include in the control limit calculation. Default is 0 or index of the first sample in the c array. end index is the index of the last element of c to include in the control limit calculation. Default is 0 which selects the last sample in the c array.
	indices to ignore is the indices of samples to exclude from the control limit calculation. Excluding samples is useful for eliminating out of control points from the control limit calculation. By default, this is an empty array.
	# samples in calc is the number of samples used in the control limits calculation.
	r:# units non-conforming/sample unit is the number of units non-conforming found per sample unit. This is identical to the input array r. These are the points plotted on the np control chart.
	np chart limits contains the limits for the np chart. UCLr is the upper control limit for the np chart. np-bar is the center line for the np control chart. LCLr is the lower control limit for the np chart. standard error is the standard error associated with np-bar.

np Chart Details

The control limit calculations are as follows:If standard values are used for the control limit calculations, then np-bar is set to std n*p0, otherwise, np-bar is calculated from the input samples as specified by the index spec and indices to ignore inputs.

, if calculated from input data, otherwise