Issues with calculating conv.value / cost for mobile devices

[elektrik...@gmail.com]

Hello!

I am using the ACCOUNT_PERFORMANCE_REPORT to calculate the metric "conv.value / cost" via following fields
- ConversionValue

- Cost

Formula used is

"Conv.value / cost" = ConversionValue / (Cost / 10^6)

To check that I'm getting correct values, using the yesterday report in Google Adwords UI.

1. Calculations are OK for Computers and tablets - in the UI and in the API data.

2. But conv.value/cost for mobile devices in the Adwords UI is higher than calculated using Adwords API report data

Could you please take a look?

[elektrik...@gmail.com]

What is weird, that I compared both metrics
- Conversion value
- Cost

And the data in the UI is EQUAL to the report output.

But UI 'conv.value/cost' is different ONLY for mobile device vs the metric calculated on our side

[Google Ads API Forum Advisor Prod]

Hello,

Can you please reply privately to author your CID, report query and report results so I can further troubleshoot?

Thanks,
Anthony
Google Ads API Team

ref:_00D1U1174p._5004Q23t8yd:ref

[Ершов Александр]

Done

Sent you the data

Thank you!

[Ершов Александр]

Update:
Contacted the Google Adwords API team and UI team.
Everyone answered in details, and we figured out what's taking place.

The solution is the following. 
You need to subtract the cost for mobile calls.

1. First, obtain it, from the Account Performance Report, filtering by
- only mobile devices
- ClickType: CALLS

2. Then, for mobile, you need to use this formula
"Manual Conv.value / cost" = ConversionValue / (Cost - Cost_for_calls)

And then the UI value will match the manually calculated ROAS ("conv.value / cost")

Thanks again!