So what are considered some of the best tests for PMF (product market fit)? Rachleff writes that “You know you have fit if your product grows exponentially with no marketing. That is only possible if you have huge word of mouth. Word of mouth is only possible if you have delighted your customer.” Tying together the concepts, Rachleff also shares that entrepreneurs too often confuse product/market fit with growth in what Ries calls vanity metrics (“numbers or stats that look good on paper, but don’t really mean anything important”). So what does? Rachleff suggests Net Promoter Score (NPS) as a great tool to predict the magnitude of customer love for one’s product/service — ideally a score of 40 or higher “to know you’re on the right track.” However, while NPS is a pretty good proxy for likely fit, it is “not nearly as accurate as having market feedback in the form of purchases.” People vote with their dollars, after all.
Marc Andreessen writes: “In a great market — a market with lots of real potential customers — the market pulls product out of the startup.” Ideally in the easiest stages of a product development process pull is happening organically (i.e., without any advertising spending).