Why market sizing becomes challenging
Publicly available data is not always sufficient, especially in emerging industries, niche segments or specific geographies. Definitions may vary, data may be outdated, and key segments may not be reported separately. In such situations, it is important to combine multiple approaches and validate assumptions.
A two-direction approach
I use a combination of top-down and bottom-up approaches to arrive at a reasonable estimate and cross-check the results.
Top-down approach
- Start from a larger, well-reported market (e.g., industry reports, government data).
- Apply relevant filters and assumptions to narrow down to the target segment.
- Helps set an initial range.
- Useful when direct data is limited.
Bottom-up approach
- Estimate the number of potential buyers or users.
- Consider purchase frequency and average pricing.
- Helps validate and refine the top-down estimate.
- Useful when ground-level information is available through conversations.
Documenting key assumptions
It is important to clearly document all assumptions, including sources, definitions, conversion factors and any ranges used. This makes the analysis transparent and easier to review or update later.
- Definition of the target market and segment.
- Data sources and their reliability.
- Conversion factors and calculation logic.
- Reason for using a specific range or estimate.
Validating through market conversations
Conversations with industry participants, including manufacturers, distributors, channel partners and customers, can help validate assumptions, understand ground realities and identify factors that may not be visible in public data. These conversations provide practical insights on pricing, demand, competitive landscape and future outlook.
Present a range, not a single number
In many cases, it is more appropriate to present a range with clear assumptions rather than a single point estimate. This reflects the inherent uncertainty and provides a more realistic view for decision-making.
Key takeaways
- Use both top-down and bottom-up approaches.
- Document assumptions and sources.
- Validate estimates through market conversations.
- Present a range with well-defined assumptions.
- Focus on practical, decision-relevant insights.