CX professionals and marketers usually value their brand advocates more than the customers who publicly criticise them. After all, positive word-of-mouth attracts potential new customers, while complaints can seem like a threat to reputation.
Many business leaders therefore assume that brand advocates buy more from the brand than critics do.
But a rigorous new study* – set to appear in the International Journal of Research in Marketing (2025) and led by professors from the US, Germany, and Australia – has revealed striking and reliable findings that challenge long-held assumptions.
Analysing thousands of customers of a large European online retailer, the researchers combined survey responses, social media activity, and actual purchase records—all at the individual level—to uncover what happens after a customer praises or criticises a brand in public.
And the findings turned conventional wisdom on its head:
- Advocacy: Customers who publicly praised the brand reduced their purchase frequency by up to 36%.
- Criticism: Frequent buyers who criticised the brand increased their purchase frequency by approximately 4%.
The customer psychology behind this is fascinating—something we can unpack another day. For now, here are two key takeaways:
- Flip the common assumption: Advocacy isn’t always a predictor of future purchases—and criticism isn’t necessarily a predictor of customer loss.
- Value your complainers: They’re making the effort to hold your brand to account. That signals they’re still invested and want the relationship to improve.
It’s a compelling reminder that the customers who highlight what you’re doing wrong—or could do better—might just be the ones who care the most.
Does this contradict NPS?
I’d say: Yes and no. The findings of this new research partially contradict the assumptions behind Net Promoter Score (NPS) – particularly when it comes to what advocacy actually tells us about a customer’s own future behaviour.
NPS rests on a core belief: that likelihood to recommend is a reliable indicator of customer loyalty and future behaviour.
But it can’t be said with certainty:
- That intent to recommend actually leads to recommendations. Numerous studies show gaps between what customers say and what they do.
- That those who say they’re likely to recommend are also likely to spend more. This study, based on actual behaviour, suggests otherwise.
- That critics are necessarily detractors. In fact, this study shows that complaints, especially from loyal or high-value customers, can reflect ongoing commitment – not a desire to churn.
Other research** shows that the correlation between NPS and actual retention or recommendation behaviour varies significantly by industry and company.
In short: Likelihood to recommend is not always a reliable indicator of loyalty or future behaviour.
Where NPS and this research do align
Despite the differences, one key area of alignment stands out.
Both NPS and this study acknowledge that engaged customers influence business outcomes.
- There’s clear business value in having customers who actively recommend the brand on social media.
- There’s also clear business value in listening to, and looking after, customers who are critical.
Both groups are engaged customers.
So what?
In sectors like banking and short-term insurance – where NPS is commonly used – these findings prompt some important questions:
- Are we undervaluing customer complaints and the potential loyalty of complainants?
- Could a high NPS be masking underlying issues that only critics are highlighting?
- How can we better leverage negative feedback to strengthen customer retention?
Let’s not overlook the power of complaints – and the customers who care enough to speak up.
Do social media fans walk their talk? The impact of advocacy and criticism on own purchasing – ScienceDirect link * Kristensen & Eskildsen (2014): Is the NPS a trustworthy performance measure? – Link