Signal to Noise Ratio - What Is the Right Size?

The concept of signal (S) to noise (N) ratios has high visibility in design of experiment circles due to the work of Taguchi and his disciples. In this paper we will look into one of the signal to noise ratios and provide an answer to the question of “How large the ratio should be to call it a significant signal?” INTRODUCTION The first step of this paper will be to define terms that are used in the “Signal to Noise” ratio analyses. The next step will be to select the ratio of interest to this paper. The final step will be to show how, using this ratio, one can arrive an answer to the question posed in the abstract above. Definition of terms as used in this paper: Customer Specification Limits are usually stated in terms of three or fewer of the following properties of the product supplied to the customer. Upper Specification Limit (USL): product exceeding this limit is deemed to be unacceptable by the customer, Lower Specification Limit (LSL): product falling below this value is deemed to be unacceptable by the customer, Nominal Value (Nom): this is the value for the property that is most desirable to the customer.