Statistical Process Controls M2A: 3 Flashcards Preview

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Flashcards in Statistical Process Controls M2A: 3 Deck (15)
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1
Q

Given the probability of A and the probability of B given A it was possible to determine the probability A given B

This is called what?

A

Bayes Theorum

2
Q

Arrangements of items where it doesn’t matter the order and duplication is not allowed

= n!
———-
x! (n-x)!

A

Combinations

3
Q

Arrangements in which order makes a difference

= n!
———
x!(n-x)!

A

Permutations

e.g.
Committee of 3 among 8 people

= 8! 8! 8x7x6x5!
———- = ——- = —————
3!(8-3)! 3!(5!). 3x2x1(5!)

= 56

4
Q

Permutations of n

Number of ways to award 3 prizes among 8 participants?

= N!/(N-n)!

Solve

A

= 8! / (8-3)!
= 8!/5!
8x7x6x5x4x3x2x1/5x4x3x2x1=
8x7x6

5
Q

A type of process variation cause by materials, tools, and work related problems

A

Assignable variation; can be eliminated or reduced

6
Q

A type of process variability caused by type of process, equipment etc.

A

Common variation (random variation)

7
Q

When a process is influenced by only common cause variation, the process is said to be what?

A

In statistical control

8
Q

When a process is influenced by one or more assignable causes the process is said to be what?

A

Not in statistical control

9
Q

This type of chart uses a center line, upper and lower control limits

A

A control chart

10
Q

The center line of the control chart represents what?

A

The average performance

11
Q

What are the two charts for variables (things you can measure)

A
  1. X charts: are in continuous units, i.e. diameter, time, length, height, or weight
  2. r charts: measure range
12
Q

What are the two charts for attributes? (Things we can count)

A

1 p charts: I.e. proportion charts. The proportion that pass or fail, Material faults, percentage of phone calls not answered in 5 rings, percentage of dissatisfied customers

  1. C chart: things we can count 1.e. Number of defects, complaints data entry errors
13
Q

When an observation is beyond the control limits this indicate what?

A

Presence of an assignable cause

14
Q

Patterns for x and r charts that indicate a likely assignable cause of variation

A
  1. One point is beyond the zone (3 SD limits)
  2. 2 of 3 consecutive points in zone A (2 SD warning limits or beyond) on one side of the center line
  3. 4 or 5 consecutive points in zone B (1 SD limits or beyond) on one side of the center line

Also, any fanning out

15
Q

What is the upper and lower control limits for x chart?

What value do you use from the table of control chart constants?

A
UCL = û + 3(SD)
LCL = û - 3 (SD)

Value A2