
The ANALYZE phase is the beginning of the statistical analysis of the
problem. The practical problem was created earlier. This phase
statistically reviews the families of variation to determine which are
significant contributors to the output.
The statistical analysis
is done beginning with a theory, null hypothesis. The analysis
will "fail to reject" or "reject" the theory.
The families of variation and their contributions are quantified and relationships between variables are shown graphically and numerically to provide the direction for improvements.
For example:
You may analyze partpart variation, shiftshift variation, operatoroperator variation, machinemachine variation.
By now the MSA has been accepted and the Study Variation has been quantified. The remaining variation is Process Variation.
Recall:
TOTAL VARIATION = PROCESS VARIATION + MEASUREMENT SYSTEM VARIATION
Most of the analysis at this phase is not whether the AFTER process performance is different than the BEFORE process performance because none of the improvements have been implemented yet, these improvements are now becoming evident and prioritized.
This phase is about statistically comparing means and variation on all families of variation to drill down and quantitatively explain the critical sources of the dispersion.
By the end of the ANALYZE phase the KPIV's that are creating the most significant effect on "Y" should be identified. Any wastes found by employing Lean tools should be identified and prioritized to improve.
The outputs of ANALYZE lead into the inputs to the IMPROVE phase.
The following links cover topics that are often applied within the ANALYZE phase:
Hypothesis Testing:
Hypothesis Test Flowcharts  make sure to use the correct hypothesis test
FTest
Student's TTest
Analysis of Variance (ANOVA)
Analyzing the sources of Process Variation:
Families of Variation
Multivariate Analysis
Statistics:
Power and Sample Size
Alpha and Beta Risks (Type I Error and Type II Error)
PValue
Confidence Intervals
Pearson's Correlation Coefficient
Spearman's Rho Correlation Coefficient
Other topics:
Takt Time
Line Balancing
Value Stream Mapping
Inventory Control
Cellular Flow
Zscore
Distributions:
Discrete Distributions
Continuous Distributions
Shape of the Distribution:
At this point in the project, and perhaps earlier in the MEASURE phase, there were delays or encounters of adversity. Here are a couple tools as reminders to keep the project on track and charging forward.
Return to the beginning of a DMAIC project
Proceed to the IMPROVE phase
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