A review of the transfer function and the critical part it plays as a fundamental concept in the DMAIC methodology.

1. Section & Lesson #:
Pre-Requisite Lessons:
Complex Tools + Clear Teaching = Powerful Results
Transfer Function
Six Sigma-Overview – Lesson 4
A review of the transfer function and the critical part it plays as a
fundamental concept in the DMAIC methodology.
Introduction #01 – Introduction to Lean and Six Sigma
Copyright © 2011-2019 by Matthew J. Hansen. All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted by any means
(electronic, mechanical, photographic, photocopying, recording or otherwise) without prior permission in writing by the author and/or publisher.

2. Using Data Analysis to Build a Transfer Function
o Why do we need data analysis?
• Remember, the goal of Lean Six Sigma is to improve a process’s…
 Effectiveness (improving the quality or accuracy of the outputs coming from the process)
 Efficiency (improving time, effort or cost of the process itself)
• To do that, we must understand what changes will improve the process.
• To do that, we must understand what controls the process.
 The control of a process is expressed through a transfer function that we build through data analysis.
o What is the transfer function?
• Depicted as Y = f(X), it’s described as “output response Y is a function of one or more input X’s”.
 It applies an equation to the IPO flow model by describing the relationship between various independent
input factors (X’s) and how they influence a dependent output response (Y).
2
Input
Process
Output
Input (X) > Process > Output (Y)
Y = f(X)
Y = f(X) or Y = f(X1, X2, X3…)
Copyright © 2011-2019 by Matthew J. Hansen. All Rights Reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted by any means (electronic, mechanical, photographic,
photocopying, recording or otherwise) without prior permission in writing by the author and/or publisher.

3. Importance of Transfer Function
o Why is the Transfer Function so important?
• The transfer function is like a control panel for a process: the more
you can understand the levers and input controls, the more you can
control and improve the output.
 Think of the picture settings for a TV.
– The transfer function would be: TV Display = f(color, brightness, tint)
 Another example is a stereo equalizer.
– The transfer function would be: Sound Quality = f(bass, mid, treble)
• Transfer functions often have coefficients (a multiplier for each factor).
 E.g, in the equation [250 = 4A + 2B + 10], what are the coefficients and how do they relate to each other?
o The transfer function is a pivotal step in the Six Sigma DMAIC methodology.
• Once you can build a transfer function, you can more easily identify, fix & control the root causes.
o Example: Why is our monthly fuel expense going up?
• Build Transfer Function:
 Fuel Expense = f(Fuel Price, Engine Size, Vehicle Weight, Driving Speed, Driving Habits, Tire Inflation, etc.)
• Questions:
 Which factor has the greatest influence on fuel expense? (large coefficient)
 Which factor has the least influence on fuel expense? (small coefficient)
 Which factor(s) can you control and how much control
do you have over them?
 If one factor changes significantly, how would that affect
the other factors? (interdependencies)
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Copyright © 2011-2019 by Matthew J. Hansen. All Rights Reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted by any means (electronic, mechanical, photographic,
photocopying, recording or otherwise) without prior permission in writing by the author and/or publisher.

4. Practical Application
o Identify 3 of the top metrics used by your organization and answer the following:
• What are all the potential factors (i.e., inputs or Xs) that influence the metric?
• Which factor do you think has the greatest influence on the metric?
• Which factor do you think has the least influence on the metric?
• Which factor(s) can you control? How much control do you have over them?
• If one factor changes significantly, how would that affect the other factors, if at all?
Copyright © 2011-2019 by Matthew J. Hansen. All Rights Reserved. No part of this publication may be
reproduced, stored in a retrieval system, or transmitted by any means (electronic, mechanical, photographic,
photocopying, recording or otherwise) without prior permission in writing by the author and/or publisher.
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