27 Oct 2023

Posted on:

10 Sept 2021

4

# Why do we only use SUM when calculating Gross Margin?

I have the same question that Tiffany has: why didn't we use the SUM function when calculating Revenue and Cogs? I am quite confused about the explanation that you provided in the video. If we need to add SUM for Gross Margin, why don't we do the same for Revenue and Cogs that we did a couple of videos before?

Instructor
Posted on:

10 Sept 2021

0

Hi Lifang,
Thanks for reaching out and good to hear from you.
We actually used the SUM function earlier too. Could you please refer to the moment when we didn't use it? Thanks!
Best,
Ned

Posted on:

22 Sept 2021

5

Okay, I think I get it.

When calculating COGS, we made the calculation for each individual sale.
Then Tableau showed us the sum in the visualization, just like it did for other columns.

When calculating Gross Margin, if we don't use SUM, then Tableau will calculate for each individual entry and then show the sum of that. So it actually adds up all the percentages of the individual sales which is why we get huge numbers.

So, when we specifically mention SUM, then Tablue takes the sum of all the months, which is what we want for the correct calculation.

Did I make sense?

Posted on:

17 Feb 2022

0

HI why did we use the sum to calculate the % of GM.
Thanks

Posted on:

07 Nov 2022

1

Very poor explanation from the instructor. Both in the video and here in the comment as well. Completely disappointed!!!! Thums down!

Posted on:

27 Oct 2023

0

@Ned, we actually did not use when making the calculated field COGS, or Revenue, for example. It is not clear why we had to use SUM for the GM% though.