Minimum effective dose in online advertising

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A while back, we talked about the minimum effective dose, the dose of medication needed to cause the desired outcome. As I’ve dug more and more into paid media and advertising over the past few years, the minimum effective dose concept has cropped up more and more.

One of the questions I’m often asked is what the minimum spend is for online advertising to be effective. To answer this question, you have to be able to answer two subordinate questions.

First, how much money do you have? This sets guidelines for what ad venues you should pursue.

Second, how competitive is the space you want to advertise in?

Let’s look at a practical example using Google’s AdWords Keyword Planner, a free tool that anyone can try out in order to buy AdWords ads. I’ll start by choosing Click and Cost Performance Forecasts, and typing in a few keywords that I’d want this blog to be known for:


When I hit go, I’m presented with the following chart:


Look at the red arrow. It’s at that point, roughly $8.28 per click, at which the more you pay per click doesn’t really get you more clicks. That’s where we get the desired effect. When you type that bid in, or move the slider, AdWords will then tell you what you need to spend to hit that click volume:


Suppose you don’t have 1,460 to spend every day on advertising? What if you only had, say,50 a day? Type that into the daily budget box and watch the chart change:


You can see above that your budget runs out before you capture even a fraction of the total number of clicks. If maximizing audience growth through paid advertising is your goal, then the 50 per day budget clearly doesn’t cut it.

The reality is that for these terms, the minimum effective dose to hit the market you want to hit is going to cost a lot of money. Monthly, that budget works out to43,800 per month in ad spend. That’s the minimum effective dose to win at owning those particular keywords. From here, my choices are to either find cheaper, still relevant keywords, accept far fewer clicks, or find a different means of marketing for the budget I have.

The above is just an example using AdWords. Virtually every online advertising tool has a campaign planner that will help you identify what the minimum effective dose is on that platform.

Before you set off on any digital advertising venture, be sure you understand the minimum effective dose and whether you have the resources to hit it. Create a spreadsheet that shows the cost per click and the minimum budget needed to get your ads to show to the segment of audience you need to be in front of.

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