Lesson 6: Statistical Process and Control Flashcards
Conformance to the requirements of the customer
Quality
requirements of the customers
painpoints
identifies specifications allowed by customer
Spec limits
voice of the customers
Spec limits
Target
Nominal Value
Lower spec limit - target - upper spec limit
tolerance
activities that interacts to produce an output or result
process
Toyota principle:
The right process will produce right results
Aspects of the output
Target - Nominal specification “Accuracy”
Tolerance - deviation, variance, “consistency”
_________ is our value preposition, product, offerings
- always have variability
output
Expensive and time consuming
- have different distribution
Batch output
Rule of thumb
sample mean distribution = batch process, minimum of 30 process
mean = x bar
double x bar = _______
total mean
What if many outputs at the same time?
- Pick samples from the batch, say 5
- Get their average, x bar
if pinagsama sama ang sample mean, it will result to a normal distribution
Central limit theorem
The arithmetic mean of a sufficiently large number of iterates of independent random variables, each with a well-defined expected value and well-defined variance, will be approximately normally distributed regardless of the underlying distribution.
Central Limit Theorem
- can detect the movement or the shift in central tendency
- can’t detect the variability and dispersion of data around the mean
X chart / X bar chart
- does not detect change in mean (because of the same distribution)
- dispersion are all the same
- detects increase in dispersion
R-chart / Range chart
To monitor the variation of the output.
R-chart
2 types of causes in variation
- common causes of variation ( ex. late ang employees, machines are dirty)
- special causes of variation (unpredictable, ex. fault in device - we don’t know kung kelan masisira.
Cost of quality : prevent variability
Prevention cost
Cost of quality : quality check, quality assurance
Appraisal cost
Cost of quality : items that are not yet delivered to the consumer (we can still address the issue)
Internal defect cost
Cost of quality: Most costly, most difficult, (nalabas na ang item sa consumer)
External defect cost
- Used to assess and distinguish sources of variability
Control charts
Use standard deviation of the sample means to define upper and lower bounds
Control charts
Upper and lower bounds
Control limits
The data outside the standard deviation
defects
___________ is the dispersion or spread of an input, process, or output around the mean.
Variability
Cause of variation - random, appear to be inherent in a process
common (natural) cause
Time consuming, expensive
managing variability
