PROMGT3 Quiz 2 Flashcards
(48 cards)
These charts are applied to data that follow a continuous distribution (measurement data)
Variables Control Charts
These charts are applied to data that follow a discrete distribution
Attributes Control Charts
Types of Process Variability
Stationary behavior, uncorrelated data
Stationary behavior, autocorrelated data
Nonstationary behavior
_________________ are most effective when the in-control process data is stationary and uncorrelated
Shewhart control charts
________________ is a collection of tools that when used together can result in process stability and variability reduction
Statistical process control
Seven major tools are:
Histogram or Stem and Leaf Plot
Check Sheet
Pareto Chart
Cause and Effect Diagram
Defect Concentration Diagram
Scatter Diagram
Control Chart
A process that is operating with only ________________ present is said to be in statistical control.
Chance causes of variation
A process that is operating in the presence of ______________ is said to be out of control
Assignable causes
The eventual goal of SPC is ___________ or _________________ in the process by identification of assignable causes.
Reduction or Elimination of Variability
If ___________________________________ and __________________, the process is out of control
At least one point plots beyond the control limits
The points behave in a systematic or nonrandom manner.
Type I Error, denoted by ________, is the probability of ____________________.
Alpha; saying that the process is out of control when it is in control
Type II Error, denoted by ________, is the probability of ____________________.
Beta; saying that the process is in control when it is out of control.
Type I error follows that the null hypothesis is ___________ whereas Type II error follows that if the null hypothesis is ______________
Rejected if it is true
Accepted when it is false
The use of 3-sigma limits, also known as _________, is applicable when the distribution of the _________ characteristic is well approximated by the __________ distribution.
Action limits; quality; normal
Warning limits are typically set at _____________ from the mean
Two standard deviations
If one or more points fall between the warning limits and the control limits, or close to the warning limits, this indicates that ________________.
The process may not be operating properly
What are the good and bad things when using warning limits?
Good: Increases sensitivity of the control chart
Bad: Could result in an increased risk of false alarms.
________ samples make it easier to detect small shifts in the process
Larger
Average Run Length (ARL) is a very important way of determining the appropriate ___________ and _____________.
Sample size; sampling frequency
Formula of Average Run Length (ARL):
ARL = 1/p ; p = the probability that any point exceeds the control limits.
The average run length gives us the _____________________ that should plot in control before _______________.
Number of samples; a point plots outside the control limits
Subgroups or samples should be selected so that if assignable causes are present, the chance for differences ________ subgroups will be maximized, while the chance for differences due to these assignable causes ________ a subgroup will be minimized.
Between; within
A statistical graph consisting of bars representing different members of a population. It is also a useful tool as this helps analysts quickly visualize the features of the data such as shape, central tendency, mean, and mode approximations. etc.
Histogram
Useful for collecting historical or current operating data about the process under investigation, This can also provide a useful time-oriented summary of data.
Check sheets
