CONTROL PHASE
Monitoring of Critical X’s & Y’s
Post full scale implementation & validation of the selected solutions in the Improve phase,
it’s important to implement the Control System for monitoring the critical X’s & the Y
measure.
The Project leaders ‘S’ & ‘B’ have identified the Y (output) & also two of the critical X’s
that they couldn’t mistake proof. The statistical tool that they decided to use was the
Control Charts.
Control charts would aid the Project leaders in monitoring of the critical X’s & Y output,
checking whether process is in control & identifying any special cause variation in the
process.
Y (output) Goal Data Type Sample Size (Variable/Fixed) Control Chart
Time to receive payments (TAT) <60 days Continuous 50(Fixed) Sub Group Size =10
X-bar & S chart
Late Payments (Defectives) <5% Discrete 50(Fixed) NP chart
Critical X’s Data Type Sample Size (Variable/Fixed) Control Chart
Incorrect Tax Amount Discrete 50(Fixed) NP chart
Incorrect Customer Address Discrete 50(Fixed) NP chart
Control Charts – Y (Output)
Y Output- Time to Receive Payments (TAT) < 60 days
Control Chart – X Bar-S
Inference – Process is stable & in control. All points in Control Chart below fall within 3
sigma from the target value so process is “in-control”.
Y Output- Late Payments (Defectives) < 5%
Control Chart- NP Chart
Inference – Process is stable & in control. All points in Control Chart below fall within 3
sigma from the target value so process is “in-control”.
Control Charts- Critical X’s
Critical X- Incorrect Tax Amount
Control Chart- NP Chart
Inference- Process is stable & in control. All points in Control Chart below fall within 3
