There are lots of people trying to sell all sorts of things to unsuspecting marketers. Here is one I came across today, NPD Group offer a product called ‘Brand-Link’ which on their webpage says “Sheryl Crow fans are more likely to drive Jeep… which means that both Jeep and Sheryl Crow could benefit from partnering on promotions!”
The exclamation mark is theirs not mine. I’m underwhelmed. Because if 5% of Americans are Sheryl Crow fans then an index of 142 for Jeep would mean that almost 7% of Jeep owners are Sheryl Crow fans (or 93% aren’t).
And the index for Sheryl Crow says that more of her fans drive Jeep than in the normal population, but not many people drive Jeep so again that index means that if she teams up with Jeep that might communicate something special to only a tiny proportion of her fan base.
Actually more Sheryl Crow fans drive Ford than Jeep.
Who cares about the index. What Sheryl Crow should ask is which car do more of my fans drive ( i.e. in total number)? And the answer will be Ford, Toyota or GM because that’s what more Americans drive.
Oh dear, indicies can be very misleading. One might have hoped for more from a market research agency, after all they are supposed to be experts in presenting and interpreting data.
Marketing Science 
Excellent point. Especially sad that it comes from a research company.
I once was handed a set of indexes for a client showing how each US DMA fit their buyers. Great info? Not at all usable. The best contradiction was that their worst indexed market (New York city DMA) was also the single market with their highest volume of sales – just because it’s so large.
Love your blog wish more people wrote about this stuff. PLease Check out my blog on Marketing Metrics if you get a chance?: ChrisMefford.Me