# Calculate Zero-centered utilties for all iterations in alpha file

Hello everyone,

I have seen the instruction for transforming raw data into ZCD, but I get stuck at the second Step:

"2. Then, for each attribute compute the difference between best and worst utilities.  Sum those across attributes."

What exactly do you mean with sum those across attributes? I have 34 variables, price(linear), color (4 levels), Label (4 levels), pricexlabel (4Level), pricexcolor (4Level), colorxlabel (16Label)+None option. I have now 7 values of (MAX-MIN) in every row/iteration (the ones for price and the None option are Zero). Do I sum them up horizontally AND vertically to receive one sum?

"3.  Take 100 x #attributes and divide it by the sum achieved in step 2.  This is a single multiplier that you use in step 4."

So basically The sum/(34*100) =X

"4.  Multiply all utilities from step 1 by the multiplier.  Now, the average difference between best and worst utilities per attribute is 100 utility points."

X* each an every utility I find in the alpha file? Do I do it differently with linear attributes?
I assumed I could go the other way round (since I have the average zcd for the utility report) but they don't all have the same multiplyer.

I hope you understand where I am struggeling and hopfeully you could help me.

Best regards
Jana
answered Jun 13, 2017 by Gold (41,270 points)