I am computing my biomarker data to compute out the Integrated Biomarker Index (IBR) to compare the integrated responses of multi - biomarker at different sites. As referred to (Devin et al., 2013) and also the early work proposed by (Beliaeff & Burgeot, 2002) as attached, the data of each biomarker must first be standardised according to this formula to get the standardised value known as Y. ; FORMULA; Y = (X - m)/s, Where (X) is the mean value for a specific site, (m) is the mean value for all sites and (s) is the standard deviation for all sites. Once the computation of Y is done the computation continues with the value of Z. Z value must be assigned with negative and positive sign following the expected biological effect of a certain biomarker; Z = Y or Z = -Y. However, what if the Y value computed from the first formula (Y= (X-m)/s) is already negative since the (m) value is higher than (X)? , (For example; the values of protein thiols would show downregulated level since they are oxidised from protein side chain, However, what if the Y value is already negative? so how should I assigned the Z value then?

Thank a lot,

Kind regards