'Gamma GT' Biochemical analysis formula is as follows for further understanding:

Gamma GT activity (U/L) = (Δ OD/min) x 1158

I would like to know the answers to the following questions:

1. What data is to be added in the place of "Δ OD/min"?

2. Once the calculation is over, Do I apply this value in 'SPSS Software' for further analysis [To find out Mean and Standard Deviation (SD)]?

Thank you in anticipation, Sir/Madam.