An L9 orthogonal DOE was performed using Minitab. The S/N in case of frictional force is negative.The response of the frictional force and rpm were negative. But in case of other output (coefficient of friction) the response values were positive. Kindly help me to know the physical meaning of the negative values.
Dear Shubrajit Bhaumik
I used L9 with 3 factors & 3 levels with Taguchi confirmation test in my last work and I explain that step by step in my article. You can see my new publication in below link.
I hope my article, would help you in your research filed.
Good Luck
http://www.tandfonline.com/doi/abs/10.1080/19443994.2015.1092893
Dear friend,
If you have got negative values for a signal, it is not a problem. In my opinion, the data acquisition was done with inverse + and - signals, and this is not such important. You can simply change the sign. The Signal to Noise Ratio (SNR) is the ratio of the arithmetic mean of the signal and the standard deviation. I didn't see the SNR values...I see Loads and RPM... Can you specify the SNR value?
If the SNR is 20, that is the Variation Coefficient is 5 %, data acquisition seems OK.
-17.6767
-17.6043
-16.4617
-19.1290
-18.0306
-17.0702
-19.9907
-19.3330
-18.3970
Normally the S/N transformations are in logarithmic scale and this could be the reason for the negative values, but anyway you must maximize these values. It would be helpful if you show the original data to verify the transformations.
Dear Shubrajit Bhaumik
I used L9 with 3 factors & 3 levels with Taguchi confirmation test in my last work and I explain that step by step in my article. You can see my new publication in below link.
I hope my article, would help you in your research filed.
Good Luck
http://www.tandfonline.com/doi/abs/10.1080/19443994.2015.1092893
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