Ever since Malcolm Gladwell’s book Tipping Point, it has become fashionable to assume that ideas and products are spread or marketed by reaching a tipping point of a number of influencers who would then spread the word. Against this was the theory that the ideas or products were spread by ‘contagion’ regardless of the number of influencers. Research published online today by the AAAS’ Science site details an experiment by researchers at NYU’s Stern Business School which shows that the truth is more complex and nuanced. The good news (from my perspective): people over 30 are more influential than those under 30. Another finding: women influence men more than they influence other women. These, and other findings, may well change the way products are marketed online going forward.