Why the spreadsheet is never the decision
Every deal eventually passes through a spreadsheet.
Numbers are projected, assumptions layered, scenarios stretched and compressed. The model becomes the focal point of discussion, the object that appears to justify the decision. It gives structure, discipline, and a sense of control.
And yet, despite the time and effort invested in it, the spreadsheet is almost never where the decision truly lives.
What the spreadsheet is good at
The spreadsheet is an organising tool. It forces clarity. It translates complexity into something comparable and communicable. It helps align conversations around a shared set of expectations. In many cases, it does exactly what it is supposed to do: it makes trade-offs visible.
What it does not do is decide which trade-offs are acceptable. That judgement exists outside the model.
The illusion of precision
One of the spreadsheet’s greatest strengths is also its most subtle danger: precision.
Numbers with two decimal points create the impression of accuracy, even when they rest on assumptions that are inherently fragile. Small changes in growth, timing or behaviour can materially alter outcomes, yet the structure of the model suggests stability. This is not a modelling flaw. It is a psychological one.
Precision reassures. It gives decision-makers something solid to hold onto in an environment defined by uncertainty. But reassurance is not the same as understanding.
Where judgement quietly enters
Judgement enters the process long before anyone looks at the final outputs.
It shapes:
Which assumptions are considered reasonable
Which scenarios are labelled “conservative”
Which risks are stressed, and which are left untouched
Two teams can build technically sound models from the same information and still reach very different conclusions. The difference is rarely mathematical. It lies in what each team is willing to believe.
The model as a narrative
Every spreadsheet tells a story. Not explicitly, but through its structure. What is included signals what matters. What is excluded signals what can be lived with. The sequence of cash flows, the choice of comparables, the framing of downside scenarios, all of these are narrative decisions disguised as technical ones.
This is why models are often adjusted not to change the decision, but to align the story with a decision that is already forming.
Again, this is not deception. It is interpretation.
When numbers are used defensively
As a deal approaches approval, the role of the spreadsheet often shifts.
It becomes less about exploration and more about defence. The question changes from “What are we learning?” to “Can we justify this?”
At this stage, the model provides comfort. It offers arguments. It helps reduce exposure if things go wrong. But it rarely reopens the fundamental question of whether the risk is one we genuinely want to take.
Why better models don’t fix this
The instinctive response to this reality is to build more complex models. More scenarios. More sensitivity analysis. More layers.
This can be useful. But it doesn’t solve the underlying issue.
Uncertainty cannot be eliminated; it can only be understood and accepted. No amount of sophistication removes the need for judgement. It only changes where that judgement is applied.
Seeing the decision clearly
Recognising that the spreadsheet is not the decision is not an argument against rigour. It is an argument for honesty. It allows us to ask better questions:
What assumptions are doing the real work here?
Which risks are we comfortable living with, and why?
What would make us walk away, even if the numbers still “work”?
These questions sit outside the model. They always have.
Why this matters
When decisions are framed as purely numerical, it becomes harder to learn from outcomes. Success is attributed to intelligence. Failure to bad luck or flawed assumptions.
But when we acknowledge the role of judgement, incentives and narrative, the process becomes more transparent. Not simpler, but more real.
Finance compounds through decisions made under uncertainty, not through spreadsheets optimised in isolation.
Understanding that distinction is central to The Compound Thinking.