No, not with definitive certainty. However, the traffic volumes involved are low enough that I have a pretty good idea of how people that buy came to know about the product or came to visit the site for the first time. A high percentage of the time, they tell me.

Never, ever have I heard, "Saw your ad on Google".

Not saying you're wrong but the goal of advertising is not necessarily a direct, short term effect of increase in sales. It could be brand recognition, which can be activated via subliminal messaging. E.g. "I heard of you before but I don't quite remember where". I'd also say that's good. If a customer found a product from a review site, that means the customer is an informed subject who is convinced they're buying the right product. Discussion fora is more of a toss up as quality and premises of discussion can be anything really.

Re: article. The screencast (that's how that's called, right?) shows 'this visitor scrolls different' and claims that is how a mobile user scrolls. But that is also how a trackpad (laptop) user who skims through the content scrolls. Basically, its how one 'scans'. Scanning is useful to determine if content is interesting.

Anyway. Its also possible we are talking bots here. Is this possibly the effect of Ad Nauseam [1]?

[1] https://adnauseam.io

I agree with you. The primary purpose of my web sites and ad campaigns is marketing, not sales.

Nevertheless, some proceeds in the latter sphere must eventually be realised from the former, by means however diffuse...

Yeah, I hear you. I would never rely on someone telling you. If you integrate adwords with salesforce you can truly track the customer from the first click to conversion, even months later. Could be worth looking into if you want to optimize your marketing spend.

Have you ever heard that they saw you on Google at all? I feel like a lot of people fail to remember the distinction between ad results and search results.

To me this immediately stood out to me as the real issue. Even for smallish products I click on an ad and rarely buy on the first visit. But I remember the name and come back to look for the product later on.

This is why tracking is so important. @Parent what is a conversion to you? Maybe you should add something light that the user can do that gives you a sense of their interest other than a purchase.

Usually, that latter function is served by the contact form. The intent of the site is to give them just enough info that they are motivated to contact us to learn more, after which they go in our CRM (Close.io, following @patio11's recommendation of it) and get extensive follow-up over what is, as you correctly surmised, often a very protracted evaluation and sales cycle. It's not uncommon for the subsequent back-and-forth to take months or, in some cases, even years, before (if) there is any real traction.

My organic traffic behaves about as I expect; they often fill out the contact form and we end up having a productive chat. Paid ad traffic, however, unfailingly bounces.

The problem is in your approach. Try switching from asking to giving in exchange for email. Then nurture the lead through email and you'll see much better results. The money is in the lists.

Thanks for the tip. But how do you suggest, within the logic of the site and my product, that I give in exchange for email? What should I offer? I can't just wall off all information behind a demand for contact info. If they have no inkling of what's behind the wall, there's no reason for them to provide it.