Help Manual

Contents






Sigma Magic Help Version 15

Taguchi Design

Overview

Taguchi design of experiments can be used to create a robust experimental design and then analyze the responses to develop a model between the input(s) and the output. This model can then be used to determine those factors which make the design insensitive to noise factors.

This tool can be added to your active workbook by clicking on Stats and then selecting Design of Experiments > Taguchi Design.

Inputs

Click on Analysis Setup to open the menu options for this tool.

Create Design

A sample screenshot of the create design menu is shown below.
inputs The tab Create Design is used to create the Taguchi design on the worksheet. The tab Analyze Design is used after performing the experiments to analyze the results and generate notes & graphs. Make sure that you are on the right tab depending on your objective of either creating a design or analyzing the experimental results.
1
Num Levels: Specify the number of levels for your factors. Currently, you can create single-level designs with 2-5 levels. Note that all factors contain the same number of levels. If a factor has less number of levels, you will have fill the remaining with dummary levels.
2
Num Factors: Specify the number of factors in your design. You can create designs for up to 15 factors. The number of factors that you can choose depends on the number of levels you pick for your design.
3
Design: Select the design (typically a Latin square design). The available Latin square designs depends on the number of levels and number of factors you specify earlier. The available designs are as follows:
OptionDescription
2 LevelsL16 (max 15 factors), L12 (max 11 factors), L8 (max 7 factors), L4 (max 3 factors)
3 LevelsL9 (max 4 factors), L27 (max 13 factors)
4 LevelsL16 (max 5 factors)
5 LevelsL25 (max 6 factors)
4
Randomize: Specify whether you want to randomize your runs when you create the design. Randomization helps with minimize the effect of unknown noise factors on your study.
5
Signal Factors: Specify if you have signal factors in your design (currently unavailable).
6
Noise Levels: Specify the number of noise levels (these are runs across the outer array) used to estimate mean and standard deviation
7
Factor Name: Specify a name for the factor. Make sure the names are unique across all factors and that the names do not contain special characters.
8
Level 1: Specify the value for level 1 for each factor.
9
Level 2: Specify the value for level 2 for each factor. Similarly complete the values for all levels. If a level does not exist, leave it blank.
10
Clear/Analyze Design: If this checkbox is set at Create design then a new design is created and saved to the worksheet. If the checkbox is set to Analyze design then any data stored on the worksheet is analyzed and the results of the analysis is updated.
11
Help Button: Click on this button to open the help file for this topic.
12
Cancel Button: Click on this button to cancel all changes to the settings and exit this dialog box.
13
OK Button: Click on this button to save all changes and compute the outputs for this analysis.
Worksheet Design Once you enter the inputs and press OK, the Taguchi design is created in the worksheet. You would need to conduct each of these tests and upload the results in the response columns (Y1, Y2, Y3, etc.).

Analyze Design

A sample screenshot of the analyze design menu is shown below.
inputs
1
Terms Included: Specify the terms to include in your model for analysis. The available options are:
OptionDescription
AutoAll terms are included in your analysis.
ManualYou can specify which terms to include in your model. You will need to specify the terms in the Terms Included box.
2
Objective: Specify the objective of your study. The available options are:
OptionDescription
Lowest is BestMinimize your response variable. An example of minimize could be the number of defects in the software.
Nominal is BestOptimize your response variable. An example of optimize could be the temperature of the room or the dimension of a product.
Largest is BestMaximize your response variable. An example of maximum could be revenue generated per month.
3
Set Terms: Select the terms to include in the analysis. This textbox is enabled if you specify Manual for the previous setting. You will need to specify the terms that you want to include separating the terms with a semi-colon. For example, A;C will include two terms A and C for this analysis.
4
Analyze Design: Make sure the checkbox for Analyze design is selected if you would like to generate analysis results.

Plots

A sample screenshot of the plots menu is shown below.
inputs
0
Pick Charts: Select the charts you would like to display for this analysis. Click on checkbox for Mean plots if you want to generate the plot of the mean values. Click on the checkbox for Stdev plots if you want to plot the results for standard deviation values. Click on the checkbox for SN Ratio plots if you want to plot the results for the Signal to Noise ratios.
1
Title: The system will automatically pick a title for your chart. However, if you would like to override that with your own title you can specify a title for your chart here. Note that this input is optional.
2
Sub Title: The system will automatically pick a subtitle for your chart. However, if you would like to override that with your own subtitle you can specify a subtitle for your chart here. Note that this input is optional.
3
X Label: The system will automatically pick a label for the x-axis. However, if you would like to override that with your own label for the x-axis you can specify a different label here. Note that this input is optional.
4
Y Label: The system will automatically pick a label for the y-axis. However, if you would like to override that with your own label for the y-axis you can specify a different label here. Note that this input is optional.
5
X Axis: The system will automatically pick a scale for the x-axis. However, if you would like to override that with your values for the x-axis, you can specify them here. The format for this input is to specify the minimum, increment, and maximum values separated by a semi-colon. For example, if you specify 10;20 then the minimum x-axis scale is set at 10 and the maximum x-axis scale is set at 20. If you specify 10;2;20, then, in addition to minimum and maximum values, the x-axis increment is set at 2. Note that this input is currently disabled and you will not be able to change this setting.
6
Y Axis: The system will automatically pick a scale for the y-axis. However, if you would like to override that with your values for the y-axis, you can specify them here. The format for this input is to specify the minimum, increment, and maximum values separated by a semi-colon. For example, if you specify 10;20 then the minimum y-axis scale is set at 10 and the maximum y-axis scale is set at 20. If you specify 10;2;20, then, in addition to minimum and maximum values, the y-axis increment is set at 2. Note that this input is optional.
7
Horizontal Lines: If you want to add a few extra horizontal reference lines on top of your chart you can specify the values here. The format for this input is numeric values separated by semi-colon. For example, if you specify 12;15 then two horizontal lines are plotted at Y = 12 and Y = 15 respectively. Note that this input is optional.
8
Vertical Lines: If you want to add a few extra vertical reference lines on top of your chart you can specify the values here. The format for this input is numeric values separated by semi-colon. For example, if you specify 2;5 then two vertical lines are plotted at X = 2 and X = 5 respectively. Note that this input is optional.

Verify

If you click on the Verify button, the software will perform some checks on the data you have entered. A sample screenshot of the dialog box is shown in the figure below. Verify The objective of this analysis as well as any checks that are performed is listed in this dialog box. For example, the software may check if you have correctly specified the input options and entered the required data on the worksheet. The results of the analysis checks are listed on the right. If the checks are passed, then they are shown as a green-colored checkmark. If the verification checks fail, then they are shown as a red-colored cross. If the verification checks result in a warning, they are shown in the orange color exclamation mark and finally, any checks that are required to be performed by the user are shown as blue info icons.

Outputs

When all inputs have been entered, click on OK to generate the outputs. Click on Compute Outputs to update the output calculations. A sample screenshot of the worksheet is shown below. outputs The analysis reports the impact of each factor on the mean value and the impact of each factor on the standard deviation value. The objective of the Taguchi design is to select those factors that have a large impact on the standard deviation to control or minimize the variation and then select the remaining factors to control the mean value.

Notes

Here are a few pointers regarding this analysis:
  • You are currently limited to 15 factors in this analysis.
  • Signal factor analysis is currently disabled.

Examples

Following examples can be found in the Examples folder.
  • Create a Taguchi design for 3 factors. The data for the exercise is given in the file. (Taguchi 1.xlsm).
  • Analyze the Taguchi design based on the results given in the data file. Determine which factor you will use to make the design insensitive to noise? (File: Taguchi 1.xlsm).