How do you track attribution, while using a linear strategy

One approach is to leverage multi-touch attribution directly in your marketing automation tools or whatever reporting tool you use. The way I've done it before is add UTM parameters for each tactic, for adroll: utm_source=retargeting and utm_medium=adroll. Then you can have one prospect with multiple campaign memberships, and each campaign member has a different UTM log associated with it. For example, I can engage with a webinar campaign but my UTM is email, and also engaged with an Ebook campaign and my UTM is adroll retargeting. If I turn into an opportunity or won deal, then you can divide up the value of my purchase amongst the different campaigns as well as UTM. So in this example, you can attribute a $$ to adroll even if it's not the "lead source" but contributed to the deal closing. Hope this helps.