How a decision is compiled and simulated

1 · Describe

the decision and the options you are weighing; keeping things as they are can be one of them

2 · Give your figures

for each option, a low case and a high case of monthly net result; the gap between the two is your doubt

3 · Simulate

the options run on the same simulated worlds

4 · Decide

the winning option, the bad, median and good case of each, and how sure the engine is

The chart runs both options from the same starting MRR over the same horizon. The parameters are illustrative.

A StoneIR decision is a short list of assignments, evaluated over simulated worlds and months. The line that defines cash, the monthly net flow, is mandatory.

Line 1

units = logit_choice(wtp, price, sens, alpha) * traffic

Line 2

clients = stock_flow(units, churn)

Line 3

cash = clients * (price - unit_cost) - fixed_cost - where(t == 0, investment, 0)

An expression is built from arithmetic, one comparison at a time, names and calls to a listed function. Attribute access, subscripts, lambdas and imports are refused with FORBIDDEN_SYNTAX. A name that is neither a declared figure, an option parameter nor a computed variable is refused with UNKNOWN_NAME.

The list holds elementary arithmetic and business mechanics: customer stock and flow, cohort survival, a buyer facing a price, adoption, queues and contagion.

exp, log, sqrt, abs, minimum, maximum, clip, where, floor, ceil, stock_flow, bass, logit_choice, erlang_c, mean_wait, abandon_below, scale_above, cumsum_t, sum_t, lag_t, ltv, poisson_pmf, sir_new, p_up_before_down, sbg_survival, sbg_churn, sbg_ltv, sbg_stock

The workspace of The Cairn offers 16 business functions, such as cash runway, a price change or a hire, grouped by area of the company.

The Cairn →

16 laws describe a single value, such as a range, a most likely value or a heavy tail. 12 describe a monthly path, such as a random walk, regimes, jumps or your own series resampled by blocks. A law outside the list is refused with LAW_UNKNOWN.

A validator walks the numeric leaves of the decision and asks each for one justification. A figure without one is refused by name, including a figure that looks reasonable. A number written inside the program is refused with LITERAL_NUMBER, apart from small structural constants.

A quote

the figure is copied from what the client wrote, times a declared conversion such as a percentage.

A dated source

a field of an entry in the source store, dated no later than the decision.

A declared default

a product default of the frame of the decision, such as the horizon, stated to the client.

A grid

an option parameter on a declared grid around another justified figure; a winner at the edge is flagged.

A logical bound

zero or one as the bound of a share, or as the switch that tells two options apart.

A missing figure is declared as unknown and stays a question to the client. Figures come from you, and results from the simulation. StoneIR reports count zero language model calls.

A decision can carry its date. A series point dated after it is refused, so a past result replays as it was computed.

A range that is too narrow hides your doubt, and a range that is too wide leaves no winner. The spread of your figures is separate from predictive accuracy. How we process your data is in the privacy policy.

How precision is shown →

The proof protocol →