Measure - Six Sigma Process and Performance Capability Measurement
Another way to express process capability is with the capability index or Cpm. Which statements describe Cpm
A cpm of more than 1 is preferred. It's used to determine variation between the process average and a target value The cpm will be less than Cpk if the process average drifts from the target value
Specification limits, process limits and process spread help determine process capability. How do you use these elements to measure process capability
Compare the actual process spread to the allowable process spread to determine if a process is in control Check that the process spread is within the specification limits.
Which methods can help to verify the normality of a process
Comparison of descriptive statistics to the normal distribution characteristics Probability Plot Histogram Specification limits A goodness of fit test for normality of population data The Anderson darling test
A process capability study measures the extent to which processes can create end products that meet customers requirements. Put the steps for performing a capability study the correct order.
Identifying measureable characteristics Verifying stability and normality Developing sampling plans and collecting data Calculating capability indices and determining the sigma level Make recommendations for process improvement
Label the chart descriptions as in control or out of control
In control: - A control chart with the data points that are just inside the upper control limit - A control chart in which there are no nonrandom sequences of data points Out of control: - A control chart that shows 13 data points alternating higher and lower -A control chart with data points that are just inside the upper control limit
Process performance can be measured by counting defects or measuring variability. Match Each performance metric to the method for which it provides data
Measuring Variability: - Capability indices - Cost of poor quality Counting Defects: - Rolled throughput yield -Parts per million -Defects per unit
Process and specification limits are required to measure performance. Match each description to the appropriate type of limit. Limit types may have more than one match.
Process: - Represents the natural variation that occurs in a process - In a call center context, may be based on the average number of calls a customer service rep can answer in an hour Specification: - Comes from the voice of the customer - In a call center context, may be based on the average number of calls a customer expects reps to answer per hour
You're testing the performance of a new product. Cp = .97 Cpk = .91 Pp = .82 Ppk = .93 sigma level = 2.9 The customber doesn't want to change specification or accept losses. What should you do?
Reduce variability
You're evaluating a particular process. Given the details below which statements accurately assess the capability performance of this process? Process capability indices: Cp= .58 Cpk = .57 Process performance indices: Pp = .54 Ppk = .54
Since Pp is less than 1, the process width is greater than the specification width With Cpk and CP values both less than 1, the process in incapable
PP Calculation
USL - LSL / 6* std dev
CPK Calculator
https://calculator.tutorvista.com/cpk-calculator.html
