Question about breakdowns and metrics

[crsilvap]

Suppose I have the following breakdown imported from Data Warehouse

Dimension 1	Dimension 2	Recipe Id (Target)	Page Views	eVar Instances
A	D	B	XXXX	XXXX
A	E	B	YYYY	YYYY
A	F	G	ZZZZ	ZZZZ

then I decide to remove Dimension 2 because It's not relevant for what I want to calculate, so I remove the column and aggregate the rows (using a tool like Excel or Python), leaving me with the following table

Before aggregation:

Dimension 1	Recipe Id (Target)	Page Views	eVar Instances
A	B	XXXX	XXXX
A	B	YYYY	YYYY
A	G	ZZZZ	ZZZZ

After aggregation:

Dimension 1	Recipe Id (Target)	Page Views	eVar Instances
A	B	XXXX + YYYY	XXXX + YYYY
A	G	ZZZZ	ZZZZ

is this a valid operation? My intuition tells me that for Page Views and Instances this is valid since the rows are exclusive. On the other hand, if I had a Visits metric it may be invalid since XXXX and YYYY may share a same visit.

How about Recipe Id (Target) or any other Target dimensions? A hit may belong to many Target Activities (AB tests for example), but Target breakdowns are individual, so if I want all Dimension 1 Page Views for element A, it may be wrong to sum XXXX + YYYY + ZZZZ because there is a chance that all Page Views of A belong to both B and G, resulting in inflated numbers of Page Views.

Thanks for any help, I'm still learning about these concepts

[Gigazelle · Accepted solution]

It depends on what metrics you're using. If you're using anything that is not hit-based, like visits or unique visitors, they would not add up. If you're using hit-based metrics like custom events, they'll likely end up pretty close.