EWMA Control Chart MCQs : This section focuses on the "EWMA Control Chart" in Statistical Quality Control. These Multiple Choice Questions (MCQs) should be practiced to improve the Statistical Quality Control skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
EWMA stands for?
A. exponentially widened moving average chart
B. exponentially weighted mean average chart
C. exponentially weighted moving average chart
D. exponentially weighted moving author chart
Explanation: In statistical quality control, the EWMA chart (or exponentially weighted moving average chart) is a type of control chart used to monitor either variables or attributes-type data using the monitored business or industrial process's entire history of output
The EWMA chart tracks the exponentially-weighted moving average of all prior sample means.
C. Can be yes or no
D. Can not say
Explanation: Yes, the EWMA chart tracks the exponentially-weighted moving average of all prior sample means.
L is typically set at _______ to match other control charts
Explanation: L is typically set at 3 to match other control charts, but it may be necessary to reduce L slightly for small values.
EWMA charts are better than Shewhart control charts in detecting the ___________ shifts.
A. Large process
B. Medium process
C. Every process
D. Small process
Explanation: EWMA charts and Cusum charts are used instead of the Shewhart control charts as the capability of these charts to find small process shifts, is greater than the Shewhart control charts’ capability.
Who did first introduce the EWMA charts?
A. Lucas (1990)
B. Saccucci (1990)
C. Roberts (1959)
D. Crowder (1987a, 1989)
Explanation: The EWMA charts, which are also called the Exponentially Weighted Moving Average charts, were first introduced in the year of 1990 by Roberts. It was a revolutionary step towards process control.
How is the effectiveness of EWMA charts by inertia effect?
C. No change
D. Can either decrease or increase
Explanation: As inertial effects increase the time for EWMA to react to a process mean shift, it ultimately is influencing the effectiveness of EWMA charts. This decreases the effectiveness of EWMA.
Which of these is not having a constant SR value?
D. EWMA chart
Explanation: We know that only Shewhart control chart have the SR value equal to constant. As EWMA chart is not a Shewhart chart, it does not have a constant SR value.
What is the value of the term w called in the SR value of a EWMA chart?
A. First EWMA value
B. Last EWMA value
C. Value of EWMA statistic
D. Weight average
Explanation: Value of EWMA statistic is the value of the term “w” called in the SR value of a EWMA chart.
EWRMS chart plots __________ on the control chart.
A. Exponentially weighted root moving square error
B. Exponentially weighted root mean square error
C. Exponentially weighted root mean signal error
D. Exponentially weighted root moving signal error
Explanation: If we have a target value for the mean, and if we want to monitor process standard deviation, we use the EWRMS charts which use Exponentially Weighted Root Mean Square error.
The EWMA chart is sensitive to small shifts in the process mean.
C. Can be yes or no
D. Can not say
Explanation: Yes, The EWMA chart is sensitive to small shifts in the process mean.