In a recent debate I had with Mark Ritson he made one empirical claim: that the iPhone was an outlier from Double Jeopardy — a smaller brand than Samsung, but with higher loyalty.  Is this correct? Does this mean that the law of Double Jeopardy is broken?

We see Double Jeopardy everywhere, from the buying of soap to the watching of soap operas. More popular items have higher penetration (more buyers) and slightly higher loyalty metrics (both attitudinal and behavioural). Because Double Jeopardy is so widespread we call it a scientific law. But this isn’t to say we don’t know of a few conditions where the law bends.

I was recently asked for a causal explanation of marketing’s Double Jeopardy pattern.

This is discussed in How Brands Grow (e.g. table 3.3 and surrounding text). Also see page 113 of my textbook. Though the most complete explanation is in the forthcoming How Brands Grow in Emerging Markets.

Hear Professor Andrew Ehrenberg describe the Double Jeopardy law in his own words.