Adverse variances as a negative figure

Hi John,

Firstly thank you for the great lectures. I have a question regarding calculating variances (of any type) on the spreadsheet for the C Section questions:
I have been copying the formula down for the individual product variances (ie cell B3-C3, B4-C4 etc) which gives adverse variances as a negative figure. I then sum all the individual variances to give the total variance, postive figure if favorable, negative figure if adverse.
I have noticed that in your lectures you only write adverse variances as a positive figure so is what I am doing incorrect? Should I deduct the favorable variances from the adverse to arrive at the net total (and vice versa)?
I understand it will produce the same figure, but is it ok to write adverse variances as a negative figure?
Many thanks