mqr.spc.XBarParams.

from_data

static XBarParams.from_data(samples, method='s_bar', nsigma=3)

Constructs XBarParams from reference samples.

Reference samples are usually taken from an historical, in-control process.

Note

Using sample range to estimate process standard deviation can be inefficient. See Efficieny of estimates of process standard deviation.

Parameters:

samplespandas.DataFrame

Reference samples. Rows represent samples and columns represent observations.

method{‘s_bar’, ‘r_bar’}, optional

‘s_bar’

Estimates process standard deviation from the sample standard deviation. Produces the traditional XBar-S chart.

‘r_bar’

Estimates process standard deviation from the sample range. Produces the traditional XBar-R chart. See notes about efficiency Efficieny of estimates of process standard deviation.

nsigmafloat, optional

Number of stderr to set control limits.