Edit/View Variables  Quality Control Tab 

Quality Control Limits for a variable can be defined. The QC Limits are used throughout OPS SQL in Time Series Graphs, Spread Reports, QC Analysis Report...
FIELDS:
Start date: The start date for the Limit.
UCL: Upper Control Limit. Typically calculated as the Mean +3 Standard Deviations of the variable for a period of time when the process is determined to be in control. 99.7% of values should be below this line.
UWL: Upper Warning Limit. Typically calculated as the Mean +2 Standard Deviations of the variable for a period of time when the process is determined to be in control. 95% of values should be below this line.
QC Mean: Typically the target. Is the average of values when the process is determined to be in control.
LWL: Lower Warning Limit. Typically calculated as the Mean 2 Standard Deviations of the variable for a period of time when the process is determined to be in control. 95% of values should be above this line.
LCL: Lower Control Limit. Typically calculated as the Mean 3 Standard Deviations of the variable for a period of time when the process is determined to be in control. 99.7% of values should be below this line.
BUTTONS:

Used to create a new limit. Inserts a new row to be filled out. 

Deletes the currently selected limit or limits. 
NOTES:
EXAMPLES: