If you look up “bathtub effect,” you’ll find quite an array of different ways the bathtub has been used as a mental model for one thing or another.
Today I want to relate the bathtub effect to marketing attribution
Imagine you’re the marketing expert at a local law firm. You rent a booth at local events. You advertise in the local paper. You hand out flyers. You send emails. You ask your current clients to tell their friends about you.
At the end of every consultation, you give your clients a questionnaire. How did you find out about us?
- Booth at a local event
- Ad in the newspaper
- Flyer in my mailbox
- Recommendation from a friend
- Google search
Almost everybody answers “Google search.” Should you conclude that all those other activities are unproductive?
No, for several reasons.
First, this is self-reported data, which is very valuable, but not perfect. Do people actually know what influenced them? Even if they did a Google search, do they know the chain of events that led them to do that? Often there’s an accumulation of causes that – to re-use the bathtub analogy in a different way – fills up the bathtub until it overflows.
If you think of one of your own purchases, it’s often difficult to remember precisely how you became aware of the product, why you became interested, or why you decided to buy.
Second, your customers might actually remember the flyer in their mailbox, but they dislike those things, so they don’t want to encourage you. Maybe a friend did recommend you, but they can’t remember his name. Or maybe they remember all of those things, but they still ended up with “how do I find this law firm anyway,” so “Google search” seemed like the right answer.
Google search is the drain on the bathtub. The water may have gotten into the tub several different ways, but it’s all going out the same way. Likewise, your customer may have heard about you in many ways, but all those things culminated in finding you on Google. Google is the drain on the tub.
Somebody might look at those survey numbers and say “why are we spending money on a booth at the spring festival? Why are we advertising in the newspaper? Everybody finds us through Google. We just need to do more Google advertising.”
The bathtub has obscured causation – or, in the marketing world, attribution.
All your efforts are filling the bathtub, but the water is all coming out one way.
The point is to keep the bathtub effect in mind when you try to do attribution. All the water flows out of one drain, but that doesn’t tell you how the water got in the tub in the first place.
