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Halloa by Mind Map: Halloa

1. Operational decision making based on SPC (actual vs interpretation

1.1. Common Cause

1.1.1. Interpreted as Common Cause Special Cause Type 1 error Chasing ghost

1.2. Special Cause

1.2.1. Interpreted as Special Cause Common Cause Type 2 error False - Missing the boat

2. In business Cp≈ 1.33 is good enough

3. Change in the distribution itself

3.1. centrality changes(mean)

3.2. spread changes(std. deviation)

3.3. Distribution shape changes

4. Whats big deal (the Unit)

4.1. Ordinary run charts are inadequate as they given guidance for interpretation in movement

5. Big Ideas

5.1. Control limits vs. Spec Limits

5.1.1. Definition => -/+3 σ

5.1.2. Objective => in control vs produces defects

5.1.3. Tool => control chart vs. histogram/box chart

5.1.4. Change trigger => process chg vs customer need

5.1.5. phylosophy => Voice of the Process vs. VOC

5.2. Causess

5.2.1. Common Random variation within the process Hard to remove usually involves process redesign Predictable

5.2.2. Special Specific/ assignable events Relatively easy to eliminate Unpredictable

5.3. Stable Process

5.3.1. All data falls under +/-3 sd I.e. between UCL and LCL

5.3.2. 99.74% values I.e. 3 in 1000 items

5.4. Capable Process

5.4.1. All data falls under USL and LSL set by the customer

6. Chart Type

6.1. Continuous

6.1.1. Single observations I(individuals) Moving Range Onlyoutside control limit rule applies

6.1.2. Averages X Bar Range

6.2. Discrete

6.2.1. Data in categories p(roportions) Usage Assumption Type Application

6.2.2. average conforming and non conforming results > 5 np>5 n(1-p)>5

6.2.3. Occurrences being counted c

6.3. Assumption

6.3.1. data is ordered by time

7. SPC Method

8. Checking for Special Causes

8.1. Extreme Points outside ULC and LCL

8.2. Shift

8.2.1. 8 or 8+ points above or below the CL

8.3. Trend

8.3.1. 8(7) or 8(7)+ points up or downward

8.4. Too quiet

8.4.1. 15 consecutive points falling within Zone B on either side of the CL

8.5. Too noisy

8.5.1. 2 or 3 points above and below the CL I.e. too much variability

8.6. Zone rules

8.6.1. Zones Zone A 2 sigma warning limits Zone B 1 sigma warning limits

8.6.2. Rules Zone A analysis 2 of 3 consecutive points falling above +2 sigma or falling below -2 sigma Zone B Analysis 4 of 5 consecutive points falling above +1 sigma or falling below -1 sigma

9. Real time monitoring

9.1. Tampering by changing process for quick wins

9.1.1. increases or upsets natural variability within the process

9.1.2. micromanaging process looses equillibrium looses capability

10. Process Capability

10.1. What

10.1.1. Process capability Ratio (Cp) how many times the allowable tolerance between USL & LSL covers for the natural process variation (UCL-LCL=> 3+3+ => 6 sigma) Cp=(USL-LSL)/6s Application Limitation process (UCL, LCL) is centred around the mean Pg. 4-24/25

10.1.2. Process Capability Index (Pck) Pck=min(Cpl, Cpu) I.e. which specification limit is likely to be breached easily? Cpl=(Xbar-LSL)/3s Cpu=(USL-Xbar)/3s Cpu=Cpl=1 when process is centred

10.2. What for?

10.2.1. process vs customer expectation (specification) measure is around the "variability"

10.3. So What

10.3.1. is the process good enough to meet customer expectations?

10.3.2. Are we overdoing I.e. is the process is too good compared to customer specification USL<UCL LSL>UCL

10.4. Link to other units

10.4.1. Proportion outside USL, LSL NORM.DIST

10.5. E.g.

10.5.1. P.25 is great example