When the KPI is not revenue, we recommend providing the value or an
estimate of revenue_per_kpi
. Providing this means that incremental outcome is
in terms of monetary units (such as dollars), not KPI. Meridian defines ROI as
incremental outcome divided by spend. So when incremental outcome is in terms of
monetary units, ROI is a unitless quantity. This makes the default ROI priors a
reasonable choice for most use-cases.
However, sometimes there isn't a clear monetary unit associated with the KPI and
no reasonable revenue_per_kpi
argument can be used. For example, the number of
free app installations where the lifetime value of an app installation isn't
known within a reasonable margin of error. In this scenario, we recommend using
Custom priors when outcome is not revenue
If it is not possible to set a custom prior based on your use case, we recommended using the default total paid media contribution prior.
Default total paid media contribution prior
When all of the following are true:
- The KPI is not revenue.
revenue_per_kpi
is unavailable.paid_media_prior_type
is'roi'
.
The default ROI prior is not used and, instead, a common ROI prior is placed on all channels such that the proportion of the KPI that is incremental due to all paid media channels has a prior mean of 40% and standard deviation of 20% (referred to as a "total paid media contribution prior"). In this case, ROI is interpreted as incremental KPI units per spend unit. To set the prior mean and standard deviation to something other than 40% and 20%, see Custom total paid media contribution prior.
Note that Meridian will default to this
behavior when the KPI is not revenue and revenue_per_kpi
is not set, so there
is no need to specify the ROI prior separately in the prior container. If a ROI
prior is explicitly set, then Meridian will use this over the default.