In other words, it is not just weight of spend that matters, it is against what it is spent. It is perfectly possible for a brand to spend more than its fair share and still not grow because its offer is not meaningfully different from the competition, or people perceive it to be too costly. Similarly, a disruptive brand may grow faster than expected simply because the relevance of its offer is immediately obvious when people come to buy the category. Finally, categories with low proportions of switching will not see the same strength of relationship between increase in market share and share of voice simply because share change is slow.
Niger Hollis on Kantar