Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
32 Cards in this Set
- Front
- Back
|
What is the control process?
|
Define
Measure Compare to a standard Evaluate Take Corrective action Evaluate corrective action |
|
|
What is the relationship between variability and processes
|
Variability is inherent in processes
|
|
|
what are the types of variability
|
Random
Assignable |
|
|
Assignable variations are....
|
variations that can be assigned to a "cause" and eliminated
|
|
|
What are example of assignable variations?
|
Equipment that needs adjustments
defective material failure of worker to follow corrective measures worker fatigue |
|
|
The variability of a sample statistics can be described by its....
|
Sampling distributions
|
|
|
According to the central limit theorem the sampling distribution tend to be....
|
Normal
|
|
|
A stable process( one that is in control) has---------- variability
|
Random or common variability
|
|
|
What is the goal of sampling?
|
is to determine whether nonrandom, and thus correctable source of variations are present in the output process
|
|
|
sampling distribution are much less variable compared to....
|
process distribution, because in sampling distribution, the high and low values in samples tend to offset each other
|
|
|
The mean of the sampling distribution equals the mean of the
|
process distribution
|
|
|
The central limit theorem states that the sampling distribution will be normal even if the population(process) is not....
|
Normal
|
|
|
Type I error is also called...
|
The producers risk, because, its places unnecessary burden on the producer to look for nonrandom variability
Also it is referred to as alpha risk |
|
|
What reduces Type I errors
|
Using wider limits i.e +/- 3.
|
|
|
Wider limits i.e -/+3 make it difficult to detect?
|
non-Random variation
|
|
|
What is Type II error
|
Its when conclusion is made that a process is in control when in reality it is not.
It is also called consumer risk,coz the consumers bear the risk of the undetected products |
|
|
What are the 4 commonly used control charts? and what are they used for?
|
two are used for attributes- attribute data are counted i.e number of defectives parts in a sample, the number of calls per day
Variables- variable data are measured, usually on a continuous scale i.e amount of time needed to complete a task, length or width of a part. |
|
|
mean and range charts are used for
|
to monitor variables
variables data are measured |
|
|
Why do we need to use both mean and range charts?
|
because the mean picks up the shifts in the process mean, and the range charts picks up the process dispersion
|
|
|
what are the two attribute control charts
|
p-chart
c-charts |
|
|
what does c-charts do?
|
since its an attribute and attributes are counted. C-charts are used for number of defects PER UNIT
|
|
|
What is P-chart used for?
|
it used to find FRACTION OF DEFECTS ITEMS IN A SAMPLE.
|
|
|
c-CHARTS
|
OCCURRENCES I.E NUMBER OF DEFECTS.
|
|
|
Process capability measures.
|
a capable process satisfies the customer, which means that the parts works
|
|
|
Capability involves...
|
individual items not sample items
|
|
|
what are control charts based on?
|
They are based on means and are found using =/- 3 standard errors ** very important to distinguish
|
|
|
capability is assessed using?
|
=/- 3 standard deviations*** very important to distinguish
|
|
|
Under the process capability the numerator is what?
|
The distance between the specification limits( the specification width)
|
|
|
if cp is less than 1, then the process is
|
NOT CAPABLE
|
|
|
if CP Iis EXACTLY 1, then the process is
|
just capable
|
|
|
if CP EXCEEDS 1, then the process is
|
CAPABLE
|
|
|
The HIGHER the cp ratio the......
|
the smaller the expected number of defects**** very important.
because, the cp ratio of 2 mean that that the spec width is 12 standard deviation, so that z=6, and the number of expected defects out of a million will be =.002 |
