SPC Fundamentals

Which of the following can cause variations in a process

• People

• Machine

• Material

• Environment

What is the advantages of having minimal variations in a process

• More products can be sold

• Fewer customer complaints

• Fewer rejects

• None of the above

Large variations in a process are

• due to assignable causes

• due only to machine

• due only to the environment

• due to normal process behavior

What percentage approximately of the area under a normal curve falls within 1 s.d. from the mean

• 69%

• 99%

• 68%

• 72%

The vertical line shown in the diagram represents what of the normal distribution

• Median of data points

• Mode of data points

• Mean of data points

• Average value of data points

The area under the normal distribution curve represented by the red hash lines comprises

• 100% of the area under the curve

• 99.99% of the area under the curve

• 86% of the area under the curve

• 99.6% of the area under the curve

Which is true about the process from the points observed in the chart?

• The behavior of the process is normal

• The behavior of the process is not normal

• The process is drifting up

• The process is out of control

The histograms of the 3 processes are plotted with the same specs limits. Which process is the least stable?

• A

• B

• C

• The are all equally stable