The Square Root Rule
Ian Lurie Jan 23 2007
Ever wonder if you could predict, with any accuracy at all, when you’ll hit diminishing returns on an advertising buy? It’s pretty important, yet almost impossible to figure out, or so you’d think.
It’s not actually all that hard, if you follow the square root rule. I’m not even going to try to explain it here though. Kevin Hillstrom has a far better explanation of the Square Root Rule than I ever will.
The important thing to note is that yes, all numbers can lie. If your marketing is totally ineffective, or if you lack baseline, historical data, chances are this formula won’t do you as much good.
Here it is again: The Square Root Rule, as explained by a Math Guy
Ian Lurie is CEO and founder of Portent Inc. He's recorded training for Lynda.com, writes regularly for the Portent Blog and has been published on AllThingsD, Forbes.com and TechCrunch. Ian speaks at conferences around the world, including SearchLove, MozCon, SIC and ad:Tech. Follow him on Twitter at portentint. He also just published a book about strategy for services businesses: One Trick Ponies Get Shot, available on Kindle. Read More