sales different of this year compare to last year in %

[lezawang]

Hi
I am watching a video on how to insert a variant chart (showing negative and positive). The author used the table below. The formula she used to find the difference is

=(B2-C2)/C2

Why is that? why not

=(B2-C2)/B2

Thanks a lot.


[TABLE="class: grid, width: 359"]
<colgroup><col><col><col><col></colgroup><tbody>[TR]
[TD]company name[/TD]
[TD]sales[/TD]
[TD]sales-previous year[/TD]
[TD]different[/TD]
[/TR]
[TR]
[TD]company1[/TD]
[TD="align: right"]600[/TD]
[TD="align: right"]795[/TD]
[TD="align: right"]-25%[/TD]
[/TR]
[TR]
[TD]company2[/TD]
[TD="align: right"]845[/TD]
[TD="align: right"]812[/TD]
[TD="align: right"]4%[/TD]
[/TR]
[TR]
[TD]company3[/TD]
[TD="align: right"]841[/TD]
[TD="align: right"]797[/TD]
[TD="align: right"]6%[/TD]
[/TR]
[TR]
[TD]company4[/TD]
[TD="align: right"]362[/TD]
[TD="align: right"]441[/TD]
[TD="align: right"]-18%[/TD]
[/TR]
[TR]
[TD]company5[/TD]
[TD="align: right"]349[/TD]
[TD="align: right"]492[/TD]
[TD="align: right"]-29%[/TD]
[/TR]
</tbody>[/TABLE]

 

[KolGuyXcel]

Usually the "formula" to calculate any "change" is

(present - previous)/previous.