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Chapter 5: Basic Six Sigma Concepts - Coggle Diagram
Chapter 5: Basic Six Sigma Concepts
Standard Deviation
variance is the root to many defects
2 step improvements: determine if the process is functional, then make improvements to remove the variation
standard deviation helps understand variation
standard deviation: distance between data points and the mean of all data
large deviation: overall wide spread of points
small deviation means closely clustered set of points
steps to calculate: 1. mean, 3. subtract mean from each point and square it, 3. find mean of new numbers, 4. find the square root of variance (mean of new numbers)
The Pareto Principle
also called the 80/20 rule
20% of the causes lead to 80% of the effects
suggest by Joseph Juran
graphical representation of data elements ranked in a bar chart, arranged in order of height with highest on left and lowest on right
made in excel: exponential, add labels: outside end
Voice of the Customer
goal: make better and consistent product
get feedback: surveys, interviews, focus groups, reviews, forms
feedback form - low cost, gathers lots of data; disadvantage: people decide to leave feedback, can skew results
survey via phone: high cost, can randomly select, draw conclusions from entire population; disadvantage: lots of labor hours, customers annoyed with calls
survey via mail: medium cost, randomly select, draw conclusions from entire population, lower cost than phone or in person; disadvantage: customer needs to send back, many dont do
social media: low cost, ongoing to seek feedback, ask questions on fly, least expensive; disadvantage: requires social media, relies on followers who already favor brand
focus groups in person: high cost, lets moderators seek in-depth answers, no travel; disadvantages: cant use data to make assumptions about general population
user or beta testing: high cost, provides feedback about specific product; disadvantages: takes time, requires experience and testers
Basic Metrics
defects per million opportunities: DPMO
DPMO equation: (number of defects in a sample/ opportunities for a defect in the sample)*1 million
defects per unit (DPU): number of defects found/ number of units in the sample
first time yield (FTY): number of good units produced/ number of units entering the process
rolled throughput yield (RTY): (number of unites -(scrap+rework)) /number of units entering process