Issue with having cumulative data in Looker Studio

Looker Q&A Looker Studio
1

Hi Team,

Screenshot
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I am currently creating different line charts. Basically, the purpose is to show specific data with the cumulative version of that same data in the same chart. I tried to use the “Running sum” aggregation, but it seems like the data from this aggregation is not accurate.

As you can see in this screenshot, my scorecard shows the true total number of unique subscribers over the entire date range, which is 23,350.

My chart’s running sum calculation is flawed. It’s not calculating a cumulative set of unique subscribers. Instead, it’s taking the number of unique subscribers from each individual day and adding them together. This method double-counts subscribers who call on more than one day, which is why the final number is higher (28,199).

Could you please assist on how to get the exact same number as in the scorecard for any date range I will choose in this page?

2

Hi, afaik, you cannot reduce the cumulative timeline to unique values, as the accumulation correctly excludes the possibility of a change in aggregation.
Summing and cumulating are different concepts that can correctly assume different values.
You are right—if you had only included the first subscriber_id in the timeline and summed it, you would end up with the grand total as the last value in your timeline.
However, your daily totals would be distorted because the subscriber_ids were apparently counted at the respective points in time. The concept of cumulation would therefore not apply, as accumulation involves forming the sum of all available values up to a certain point in a list or report.