Market Sizing: Distinct Amazon Shoppers Who Post a Product Review in a Month

Estimate how many distinct people write at least one review on Amazon in a typical month. Someone who posts several reviews during the month counts only once. Explain your scoping choices, show the calculation, and check whether your result is reasonable. ```hint Count people, not reviews Reviews come from buyers, and one buyer can post many. Start from the people who shop in a month, and think about what makes some of them far more likely to review than others. ``` ### Clarifying Questions - Which marketplace should the estimate cover: the United States only, or all of Amazon's country sites? - Does a star rating left without written text count as a review, or only written reviews? - Should seller feedback and reviews of non-physical items such as digital content be included, or only product reviews? - Are we counting people or reviewer accounts, given that households often share one account? ### What a Strong Answer Covers - A clear definition of the unit (distinct reviewers in one month, deduplicated) and of the scope. - A structured equation that starts from monthly buyers and a probability of reviewing, segmented by a factor that genuinely changes review behavior. - Every input labeled as an assumption with round numbers and a short justification, and correct arithmetic. - A sanity check from a second angle, such as the implied share of orders that get reviewed. - Awareness of which assumptions the answer is most sensitive to, and a plausible range. ### Follow-up Questions - Your estimate turns out to be off by a factor of three. Which assumption is most likely wrong, and how would you check it with internal data? - Suppose the company changed how prominently it asks buyers for a review after delivery. Which inputs in your model would move, and by roughly how much? - The team wants to double the number of monthly reviewers. Which segment from your breakdown would you target first, and why?