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Control charts are constructed to decide whether a process is under statistical control and to monitor any departures from this state. This means that stability of some process properties over time is tested using certain statistical assumptions about the process (data it produces). Commonly considered properties are mean, variance (standard deviation), distribution shape or proportion of faulty items. The Shewhart control charts were invented in 1932. They are based on monitoring events, which are very unlikely when the controlled process is stable. Any incidence of such an event is taken as an alarm signal suggesting that stability of the process was broken and the process changed. Upon receiving such signal, possible causes of the change should be investigated and some correcting steps taken. One example of such an unlikely event is the situation when the control limits (UCL or LCL) are exceeded.

Special features:
X-Bar Charts for data with missing cells
Charts for asymetric data
X-Bar and S / R
X-Individual and R
NP, P, C, U - Charts

PDF Shewhart Control Charts - Pdf manual


Shewhart Control Charts

Shewhart Control Charts

X-Bar Chart Output Protocol:
Control chart x-individual      
Task name : Sheet1    
No transformation      
Max. subgroup size : 1    
No of rows : 52    
Chart type : x-individual Variability : R
Central line : 7.045072115 Central line : 0.461397059
Defined by : Process data Defined by : Process data
LCL : 5.817952278 LCL : 0
UCL : 8.272191953 UCL : 1.507384191
Defined by : Process data Defined by : Process data
Capability indices :      
Index : Value : Lower limit : Upper limit :
Cp : 1 0.864540983 1.135006554
Cpk : 1 0.842446855 1.1.4601
Estimate (Heavlin) :   0.842446855 1.1.4601
Estimate (Kushler) :   0.862097414 1.137902586
Estimate (Franklin) :   0.872168099 ------
Cpm : 1 0.865205478 1.134346174
Cpmk : 1    
Rules violation :      
No. : Mean : Range : Rule :
45 1.5.3125 1.453125 1 point outside control limits
46 7 1.1.6875 1 point outside control limits
Different types of control chart constructed by QC-Expert

Regular Control Chart X-bar / X-Individual and R:
Shewhart Control Charts

X-Bar and S Chart for unequal group size
Shewhart Control Charts

Chart X-individual and R for asymetrically distributed data using Transformation
Shewhart Control Charts

NP Chart for attributes
Shewhart Control Charts

P Chart for attributes
Shewhart Control Charts

C Chart for attributes
Shewhart Control Charts

U Chart for attributes
Shewhart Control Charts
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