You must have ion district administrator access in order to create and edit CBMs.
This is the "safest" way to write the formula since it forces the fields into integers.
iif((toInteger(f1) - toInteger(f2)) - (0.5* toInteger(f2)) < 0, 0, Round((toInteger(f1) - toInteger(f2)) - (0.5* toInteger(f2)) + 0.1 , 0) )
However, it is possible to use a simpler version as well.
The formula reads as:
“If the number correct minus half the errors is less than zero, the score is zero. Otherwise, calculate the same and round it up to a whole number whole number).”
".1" is added because the round function uses something called "bankers rounding" which didn’t guarantee that .5 would round up.
In order to administer the CBM, please follow this article.