As of release v1.1.0, Meridian now enables channel-level contribution priors for organic and non-media treatments. This will allow you to set contribution priors that reflect your prior beliefs for these treatment types and ensure the total contribution does not exceed 100%.

Going forward, channel-level contribution priors will be the new default option for organic media and non-media treatments. This enhancement can help address challenges with negative baseline estimates, which occur when the effects of treatment variables are overestimated (incremental outcome exceeds expected outcome). See here for more details on the new functionality and how to leverage it.