Although for years the marketing science community has been actively proposing models for measuring the effectiveness and return on marketing investment (ROI), marketing attribution remains one of the major issues today. In fact, the Marketing Science Institute has identified attribution marketing as the number one priority since 2016. In this research we use the calibrated structural equations from a partial least squares model from previous research to estimate the impact of advertising on web and store sales for an omnichannel retailer of electronic consumer goods. From this model, as a novelty, the research derives the marketing metrics on percentage of sales attributable to each advertising channel, including, online, offline, paid search advertising and branded search queries. Finally, we present some managerial implications of our model. We find that not considering the simultaneous cross effects of the different advertising media, managers may make incorrect decisions inferring attribution from misleading calculations.