Standard Score Calculation

    Standard Score Calculation
    
    Mean = Average of all absolute value of Observed - Expected values.
    StdDev = Standard Deviation of all Observed - Expected values
    
    For each X = O - E, perform the following calculation:
    
    Standard Score = (X - Mean) / StdDev
    
    Verification:
     1. Run python3 normalized_bias_calculator.py.
     2. Check data in SubstitutionAnlysResults.xlsx
    
    **Note: Using the meaning on the input data set:
    2SubstitutionAnlysML_INPUT.xlsx produced symmetrical results for transitions
    e.g. A -> T, T -> A were the same value.