Hi

Hoping someone can shed some light on a calculation issue i have.

The scenario is i want to be able to calculate the % of change positive or negative comparing two values last yeat versus this year.

Eg This Year the value is 2, Last year the value was 0, so there is a 2 point difference yoy, so how do i calculate this as a percentage?.

I have been trying to get some dax calculations to work for me. See the table below. But i dont think i have the % difference calculation working properly as the result for where the value is 2 for this year and 0 for last is producing a 0% yoy difference result when applying my calculation.

```
My calculations in the table are structured as follows
(VAR)Total Serious Incidents =
VAR SIValue =
CALCULATE([Total Serious Incidents])
RETURN
COALESCE(SIValue,0).
Serious Incidents LY (VAR) =
VAR SILYValue =
CALCULATE([Total Serious Incidents],SAMEPERIODLASTYEAR(Dates[Date]))
RETURN
COALESCE(SILYValue,0)
Difference Serious Incidents LY =
IF(ISBLANK([Serious Incidents LY (VAR)]),BLANK(),[(VAR)Total Serious Incidents]-[Serious Incidents LY (VAR)])
% Diff LY Serious Incidents = DIVIDE([Difference Serious Incidents LY],[Serious Incidents LY (VAR)],0)
```

so how do you want the logic to work on paper:

in your example

"This Year the value is 2, Last year the value was 0, so there is a 2 point difference "

since last year it was 0 and this year it is 2 the percentage increase is infinity.

what value would you want to show… infact how will you like the issue to be handled when there is 0 incident last year but some incident in current year.

This is what google says

“There is no **rate of** growth from **0** to any other number. That is to say, there is no **percentage of increase** from **zero** to greater than **zero** and there is no **percentage of** decrease from **zero** to less than **zero** (a negative number)”

should not you display Blank() or [NaN] or [N/A] in such cases?

Hi

So then is calculation correct but not reflecting in the scenario i am wanting present.

What i am after is the positive or negative variance showing as a percentage based on last years results. So where there has been an increase or a decrease in the value this year compared to last year what is percentage of change

it seems to be working where this year has a 0 value and last year has a number value e.g 2 which is showing in the image below, the percentage difference is calculating the results -100%

But where there is 0 in the last year column and a value in the current year then the % difference calculation is 0%. So my total percentage change is not correct.

gosh i hope i am making some sense

Hello @AoakeP -

i think you are going down a rabbit hole .

when you drop from a number to 0 it means you lost everything that is 100% lost … so in your e.g. if you have 2 points last year and this year you have 0 point % decrease = change divided by last year value or -2/2 * 100 = -100% drop

however when the base value is 0 you cannot say how much the increase has been… e…g you have $0 in your pocket last year and $100 this year you cannot express the $100 gain as a percentage increase. go with “N/A” in such cases.

I agree thanks I have looked over the calculation again and it is rolling up the total % change at the company level correctly.

Thanks for your help.