In this equation, y is the value of measured response for each test, and n is the
number of repetitions of each test (in this study was 3). S/N Ratio from eq. (1) only can
be used when the test has more than one replication, if n=1 the average data analysis
which is a different method should be used (Roy, 1990; Roy, 2000).
The value of output in optimum level is calculated from equation (2) (Roy, 1990):