Charts and stuff Flashcards
Control limits are
limits driven by the natural variability of the process
Process Standard Deviation is necessarily equal to the sample standard deviation of the same process. (TF)
False
There is no need of revisions of control limits once calculated by the equation of control limits. (TF)
False
Never attempt to interpret the X chart when the R chart indicated the out of control condition (TF)
False
The 3 sigma limits on Xbar control charts imply that the type I error is
0.0027
A variable quality characteristic will have both
Mean and Variability
the center line for a x double bar chart denots
mean of means of the sample
equation that gives the correct value of A2 used in the equation for control limits of an xbar chart
3 / d2 * SQRT(n)
When the upper and lower natural tolerance limits are equal to the upper and lower specification limits, the process capability ratio, cp is ___
1
Tolerances are said to be
limits of natural variability
A single measurable quality characteristic, such as dimension, weight, or volume, is called
Variable
X bar chart is a ___
Variable control chart
Stratification is defined as
Tendency for the points to cluster artificially around the center line
Process variability can only be described and monitored by the s control chart
False, s control chart and R control chart
Shift in the process level can be seen on the control chart when
Introduction of new workers or change in methods
In the general equation of UCL of a control chart, for nay xbar chart, which of these is used as the estimator of u(mean)
X double bar
Quantitites that can be numerically measured, can be plotted on a ___
x bar chart
S chart is used to monitor ____ of a quality characteristic
Variability
Once a set of reliable control limits is obtained, we use the control chart for the monitoring future production. This is called
Phase II control chart usage
Specifications have the same meaning as ___
tolerances
When R chart is out of control
Eliminate the out of control points and recalculate the control limits
X bar chart monitors
Between sample variability
Which chart should be interpreted first when both x bar chart and R chart are indicating a non random behavior
R chart
Unlike X bar chart, which measures between sample variability only, an R chart is used to monitor ___
within sample variability only
If the sample size for a P chart is 50, and the value for the center line is 0.2312 what will be the value of the LCL of the chart
0.0524
