The baseline is the amount of conversions that would remain if you stopped your marketing activities in the short term. Since marketing, done right, in the long run contributes to a higher baseline, ceasing marketing activities for a longer period of time will of course also decrease the baseline.
The baseline includes the effect of a longer term, underlying trend, special events like Xmas and Black Friday, seasonal effects like month or weekday and other potentially user-provided inputs like pricing or distribution related variables. Adtriba calculates the baseline using a two-step-process.
First, the effect of organic traffic (SEO, Direct, SEA-Brand) and all media (upper and lower funnel) on conversions (revenue) is calculated. Then, the effect of the upper funnel, non-search, media (TV, Social / Display Prospecting) on the organic traffic sources is calculated.
This allows us to estimate the share of organic conversions that were actually driven by upper funnel media investment. This share is then removed from the organic traffic contributions and re-allocated to the upper funnel channels. What remains forms the baseline, together with some residual, unallocated baseline (think of it as a sort of y-intercept) that is usually present in the model.