An evidence level is a rating of how much confidence to place in an assumption, based on the strength of the evidence supporting it, from an untested assertion or rough estimate through to validated, real-world data. It turns "how sure are we?" into an explicit, comparable signal that guides where to gather more evidence before investing further.
Every strategy hypothesis rests on three kinds of assumption, and each calls for a different kind of evidence. Choices are the decisions the team controls, such as which customers to serve, what to build and how to sell it. A choice needs a commitment decision, and the evidence question is what it depends on being true. Assertions are beliefs about how others will behave: that customers have the need, that a channel partner will carry the offering, that a competitor will not respond. They are tested through research and validation. Uncertainties are quantities the team can only estimate, such as price, adoption rate or cost per unit. They are carried as ranges, and the evidence behind a range determines how wide it should be.
An evidence level rates how well supported each of those assumptions is, on a scale that runs from a rough guess to real-world actuals. What counts as enough evidence depends on the stage. Early in a venture's development, the strategy is modeled at low fidelity, the investment at stake is small, and directional or anecdotal evidence is sufficient. As the venture moves through stages, fidelity rises, the investment grows, and the evidence expected rises with it: structured research in the middle stages, and definitive, quantitative support before the venture scales. The same assumption can be adequately supported at one stage and under-supported at the next.
Paired with an assumption's impact on the outcome, the evidence level tells a team which assumptions to test first: the high-impact, low-evidence ones. It rates the evidence the team actually has, not how confident the team feels. The underlying discipline, converting assumptions into evidence before scaling investment, descends from Discovery-Driven Planning, customer development and validated learning, and from evidence-based gate decisions in Stage-Gate. Growth Forge® Software carries evidence levels through the Assumptions Manager and Evidence Gathering tools, where they prioritize tests and feed the Strategy Evaluation. For how evidence levels shape a model's input ranges, see the Modeling Uncertainty page at /supporting/uncertainty; for how evidence requirements rise across stages, see the Innovation Methodology page at /supporting/methodology. Related Terminology Index entries: Strategy Choice Assumptions; Uncertainty Assumptions; Stage Gate.
