OMIS 2010: Stat Process Control (Week 11)

What is quality?

ability to meet customer expectation

What does TQM stand for?

|:| total quality management

What are the TQM pillars?

• improvement

• involvement

• satisfaction

What is SPC?

|:| stat process control

• current capability / performance

• investigate change

• identify / eliminate variation

What is the sample process?

1. sample → stats

2. distribute

3. identify distribution

• central tendency

• variation

• shape

1. IF natural variation, stable sampling distribution

2. IF assignable variation, determine cause

What is a control chart’s data point?

inspection event

What is the control chart process?

1. U&L/CL

2. inspection

3. does measurement fall within U&L/CL?

What are the control chart patterns?

pattern test <

• trend

• cycle

• bias

• level

• dispersion

What are the data types?

• variable

  • value

  • whole / fraction

  • continuous random variable

• attribute

  • defect

  • binary / count

  • categorical // discrete random variable

What are the continuous random variable control charts?

use together

• x̄

• r

What are the categorical // discrete random variable control charts?

• c

• p

What is an x̄ chart?

process mean

What is a r chart?

process variability

What explains why one can use x̄ & r charts if data can have any distribution?

central limit theorem

What is the central limit theorem formula?

$$\sigma_{\bar{x}}=\frac{\sigma}{\sqrt{n}}$$

What are the population distributions?

• beta

• normal

• uniform

What is the control limit process?

1. N samples’ n measurements → sample mean / standard deviation & mean standard error

2. sample mean / standard deviation & mean standard error → U&L/CL / control chart

3. sample plot → in-control?

4. if outside point, assignable variation → act

5. sample / reset U&L/CL // 3.

What is the x̅̅ x̄-chart notation?

sample means’ mean

What is the z x̄-chart notation?

normal standard deviation number

What is the σ_x̄ x̄-chart notation?

mean standard error

What is the σ x̄-chart notation?

population standard deviation

What is the R̄ x̄-chart notation?

samples’ average range

What are the A₂ x̄-chart & D₄ / D₃ r-chart notations?

control chart table factors

What is the R_i r-chart notation?

i sample range

What is the p-chart use?

binary

• look at NO-error period → apply to other

What is the c-chart use?

count

What is the p̄ p-chart notation?

defective samples’ mean fraction

What if assignable variation is observed?

• NOT use in new U&L/CL

• after improvement, new U&L/CL if changed random variation extent

What is the c c-chart notation?

defect mean

What are the binary data characteristics?

• 2 states

• observable / known observations

• fraction / proportion / %

• binomial distribution

What are the count data chracteristics?

• defect state

• unobservable / unknown observations

• whole number

• poisson distribution