Statistical Process Controls M2A: 3

Question 1

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?

Answer 1

Bayes Theorum

Question 2

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

= n!
———-
x! (n-x)!

Answer 2

Combinations

Question 3

Arrangements in which order makes a difference

= n!
———
x!(n-x)!

Answer 3

Permutations

e.g.
Committee of 3 among 8 people

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

= 56

Question 4

Permutations of n

Number of ways to award 3 prizes among 8 participants?

= N!/(N-n)!

Solve

Answer 4

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

Question 5

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

Answer 5

Assignable variation; can be eliminated or reduced

Question 6

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

Answer 6

Common variation (random variation)

Question 7

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

Answer 7

In statistical control

Question 8

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

Answer 8

Not in statistical control

Question 9

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

Answer 9

A control chart

Question 10

The center line of the control chart represents what?

Answer 10

The average performance

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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

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

Question 13

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

Answer 13

Presence of an assignable cause

Question 14

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

Answer 14

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

Question 15

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

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

Answer 15

UCL = û + 3(SD)
LCL = û - 3 (SD)

Value A2