PROMGT3 Quiz 2 Flashcards
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
Frequency distribution of attribute data (or histogram) arranged by category. Also often identified as the 80-20 rule.
Pareto Chart
Once a defect, error, or problem has been identified and isolated for further study, potential causes of this undesirable effect must be analyzed through this diagram
Cause and Effect Diagram
A picture of the unit showing all relevant views. This diagram is used to analyze and determine if the location of the defects in the unit provides any useful information about the potential causes of the defects
Defect Concentration Diagram
Plot of two variables that can be used to identify any potential relationship between the variables
Scatter Diagram
X-bar formula:
Sample average
Formula for Upper Control Limit (UCL), Lower Control Limit (LCL), and Control Limit (CL):
UCL = Mu + 3 (sigma/sqrt (n))
CL = Mu
LCL = Mu - 3 (sigma/sqrt (n))
Formula of the standard deviation of the sample average:
sigma/sqrt (n); wherein n = sample size
X-double bar formula:
Average of the Averages (X-bar)
The general manager wants to receive a QC report that reflects the exact quantity of finished goods that are rejected from the line on a daily basis. What SPC tool is used?
Check Sheet
The president must prioritize his action plans to alleviate poverty based on the impact to the Philippine economy . What SPC tool is used?
Pareto Chart
A manufacturer of wine always encounters complaints on foreign matters in the finished products. They would like to know why this complaint recurs. What SPC tool is used?
Cause and Effect Diagram
The manager wants to know if the botting process is stable in terms of bottle contents. What SPC tool is used?
Control Chart
The manager of GDK electronics company would like to determine the various causes of lens contamination. What SPC tool is used?
Cause and Effect Diagram
The quality circle would like to determine if kettle temperature affects the viscosity of the chemical compound. What SPC tool is used?
Scatter Diagram
The SDT wants to detect irregularity of the pressure gauges at any time to take necessary action immediately. What SPC tool is used?
Control Chart
The QA manager would like to determine the best supplier of PVC compound used for the manufacturing of plastic tubes
Histogram
The supervisor would like to monitor the frequency of defects occurring in the packing process
Check Sheet
The operator wants to know which of the many problems in the line he will focus first
Pareto Chart
Which chart type would be used to monitor the number of errors per page in a printed document?
U Chart
Which chart type would be used to monitor the average weight of contents of a box of cereal?
X-bar chart
Which chart type would be used to monitor the fraction of a production lot of calculators that had malfunctioning keys?
P-chart
Which chart type would be used to monitor the number of surface blemishes (scratches, rubs, etc) in square meter of flat glass?
C Chart
Which chart type would be used to monitor the range of the diameter of forged steel rods within a production lot?
R Chart
An SPC tool which is particularly useful for identifying a potential relationship between two variables
Scatter diagram
