1. Using the Design of experiments method
3/24/ by: frank polanco

2. Agenda Why should I use a Design of Experiments (DOE)?
When should I use a DOE?
What is a DOE?
How do I use a DOE?
Questions

3. Why should I use a DOE?
It is a highly efficient method of carrying out an experiment. A DOE reduces the amount of time needed to perform the experiment.
It is an effective tool when used on the right problem. It minimizes the amount of resources required to perform the experiment when compared to other methods.
A benefit of this approach is learning further insight into your process.

4. When should I use a DOE?

5. When should I use a DOE?

6. Old Faithful Old Faithful
When should I use a DOE?
Old Faithful
Old Faithful
What does it do?
What does it do?

7. When should I use a DOE?
OFAT
DOE

8. When should I use a DOE? OFAT DOE One Factor at A Time
When you want to find out the effect of one or two variables in an experiment.
Design of Experiments
When you want to find out the effect of three or more variables in an experiment.
When you want to also know the effect of combined variables in an experiment.
Extrapolate best settings based on data

9. What is a design of experiments (DOE)?

10. What is a design of experiments (DOE)?
A DOE is comprised of several elements:
Factors
Levels
Design Matrix
Outputs
Effects
Interactions
DOE

11. What is a design of experiments (DOE)?
Factors
This term for a DOE represent the main contributors to the experiment. Usually known as variables.
Levels
These are the adjustment that you can make upon a factor.
Design Matrix
A table that depicts every possible combination of levels and factors.
Outputs
These are the individual trial results within a DOE
Effect
This is the ‘effect’ that a factor or a combination of factors has on the Outputs.
Interaction
This is the combined ‘effect’ that two or more factors can have on the Outputs.

12. What is a design of experiments (DOE)?
Factors
Bass
Treble
Volume

13. What is a design of experiments (DOE)?
Levels
Quiet
Loud
Low
Lower
Higher
High
Bass
Treble
Volume

14. What is a design of experiments (DOE)?
Output

15. How do I use a DOE?
We will only consider the example of a Full Factorial DOE. This is in contrast to a Fractional Factorial DOE.
A Fractional Factorial DOE is one that has a ‘fraction’ of runs / experiments of a Full Factorial. These are best utilized when running a larger DOE. That is, one with multiple Factors and Levels that would be costly and/or time intensive and you can’t afford either.
Next, an example…

16. How do I use a DOE?

17. How do I use a DOE?
Get to know the problem that you want to solve extremely well. Find the Factors that should be studied.
In order to understand the problem you can employ a multitude of other tools such as: Process Flows, Scatter Diagrams, Paretos, Checksheets, 5 why’s etc.
This is when forming a cross-functional group can really benefit your experiment. Admitting that you don’t know the whole process is OK, rely on a team of subject matter experts, operators, maintenance, and so on to determine the important factors.

18. How do I use a DOE? You and your team and decided on three factors:
Fertilizer
Water
Agricultural Gypsum
AKA (Calcium)

19. How do I use a DOE?
Decide on a proper measurement system for the Effect.
This step is crucial as it can make your data meaningful or irrelevant, take your time deciding what to use.
Stay away from qualitative measurements like dim/bright or pass/fail criteria. Use a quantitative measurement whenever possible.
Get creative with the way you can measure the effect. Don’t settle for whatever system has been used up to this point. For example, if you’re looking at how dim/bright something is, use a Lux Meter to measure a light’s brightness.
If you’re going to use a measurement tool, ensure that it passes a Gauge R&R. That way your measurements will be sound.

20. How do I use a DOE?
You and your team and decided on the measurement system for the Effect of the experiment:
A calibrated digital weigh scale which will measure in Kilograms

21. How do I use a DOE?
Decide how many levels you’re going to use and build your design matrix
Now that you have the important Factors figured out, use your knowledge and the same cross-functional team to decide how many levels should be used for each Factor.
This will help you determine what design matrix you will be using. Try to stick to two levels when possible.

22. How do I use a DOE?
You and your team agreed on two Levels per Factor:
Since you have three Factors at two Levels each, you can easily calculate the amount of runs or individual experiments you’ll need to complete the full experiment. They are calculated as an exponential number where: 23
# of Factors
# of Levels

23. How do I use a DOE?
You and your team agreed on two Levels per Factor:
Since you have three Factors at two Levels each, you can easily calculate the amount of runs or individual experiments you’ll need to complete the full experiment. They are calculated as an exponential number where:
23= 8
# of Runs

24. How do I use a DOE?
Create your design matrix making sure that all possible combinations of Levels and Factors are used. In this case we’re using +1 to represent the high setting and -1 the low setting.
Run
Run Order
Fertilizer
Water
Calcium 1 6 -1 2 8 +1 3 4 5 7

25. How do I use a DOE?
Decide what you will use for the high and low settings of each Level for your Factors.
The team should help you decide upon the value of each level as these must be realistic. If not, the experiment will yield unusable results.

26. How do I use a DOE?
You and your team review each Factor carefully. Drawing from experience and/or prior data, you arrive at realistic settings for each Factor.
You are very careful as to not pick any unrealistic settings. For example, for the high setting Level of Water you shouldn’t use so much as to wash away the plant’s soil.
Factor
High Setting
Low Setting
Fertilizer
500g
100g
Water
400mL
150mL
Calcium
200g
50g

27. How do I use a DOE?
Populate your Design Matrix with the actual high and low Level settings.
This table can now be used as a guide to conduct the experiments.

28. How do I use a DOE?
You now enter all of your high and low settings onto your Design Matrix.
Run
Run Order
Fertilizer
Water
Calcium 1 6
100g
150mL
50g 2 8
200g 3
400mL 4 5
500g 7

29. How do I use a DOE?
Conduct all experiments within your matrix using your run order as a sequence (Randomization).
Create a new column for Outputs per run.
Consider running all runs multiple times, that is completing all runs before starting again. This is called Replication.

30. How do I use a DOE?
You add the Output column to your Design Matrix and conduct each experiment using the Run Order for cadence.
Take the data collected and enter it into the ASQ “3-factor-doe- template” Excel file.
Run
Run Order
Fertilizer
Water
Calcium
Output 1 6
100g
150mL
50g 2 8
200g 3
400mL 4 5
500g 7

31. How do I use a DOE?
The Excel file graphs your Main Effects and Interactions.
This bar signifies the strongest interaction
The larger bar signifies the strongest Effect

32. How do I use a DOE?
The Excel file also graphs your Interactions versus their levels.
This line that’s on an angle signifies a strong interaction with these settings
This flat line signifies a weaker interaction at these settings

33. How do I use a DOE?
Under the ASQ.org website you can find a host of great information regarding DOEs. If you go to the following link you can find a nice DOE “Overview”.
tools/overview/design-of-experiments.html
The procedure on how to use a DOE is similar between different sources. But the link below gives a nice example on how to do the DOE manually.
tools/overview/design-of-experiments-tutorial.html
We will focus on how to perform a DOE using the Excel spreadsheet from ASQ.org linked below.
template.xls