inferTIC

Resources · Method

Published methods, cited to the page.

Three principles the code enforces: every number originates in the engine; every number carries provenance; nothing is derived from a closed-box estimator’s content. This page states the method those principles serve.

The calculation chain

Each step is a pure function. The trace object shown to the user is the record of these calls, in order, with inputs and outputs at each step.

  1. Sizing parameterUser input per item — area, volume, power, duty. A warning if it lies outside the correlation’s validity range.
  2. Purchased costFrom the library correlation at its base year and base CEPCI, or a vendor quote that bypasses the correlation and is tagged as such.
  3. Material and pressure factorsFrom the library record; multiplicative on purchased cost.
  4. EscalationCEPCI from the correlation base year to the estimate cost date. The index table is user-editable and the rows used are snapshotted into the estimate file.
  5. Location factorThe library ships the US base location; any other location is a company row or a user override with a required note.
  6. CurrencyUser-set FX rate and date.
  7. Installed costSelectable: Lang, Hand, Guthrie bare-module, or user-defined percentages.
  8. Indirects, EPCM, owner’s costPercentages, defaults by class, editable.
  9. ContingencyPercentage, default by class from a cited source, editable.
  10. Total and Monte Carlo bandTriangular or PERT per line or group, seeded; the seed is stored.

Class 3 method

AACE 18R-97 describes Class 3 as semi-detailed unit costs with assembly-level line items, prepared from preliminary quantity take-offs. The tool implements exactly that and nothing more. A bulk line carries a discipline, a quantity and a unit; quantities arrive by import of a line list or MTO, by manual entry, or by geometry from user-entered coordinates and rack polylines. Unit rates and labour norms come from a versioned company set, every row sourced, or from a public seed flagged as such. Labour is hours times craft rate times a productivity factor that the estimator states with a note.

Class 3 is claimed only when the user-stated definition level is within the Class 3 band and at least one line is quantity-priced. There is no library threshold on the quantity-priced share of cost; the share is reported so a reviewer can judge it.

AACE class bands

Rendered from the library’s class table, the same record the app reads. The class is assigned from the definition level the estimator states. No class better than 3 is ever presented or implied.

AACE 18R-97 classes as stored in the methods library (classes.json)
ClassProject definitionExpected accuracy
Class 50–2 %-50 % / +100 %
Class 41–15 %-30 % / +50 %
Class 310–40 %-20 % / +30 %

The definition levels were checked against a printed reprint of the classification table; the accuracy percentages rest on the recommended practice as stated in the project brief and are noted in the record as not yet verified against a printed page of the RP itself.

Published sources

Equations and coefficients are implemented as methods, presented in the library’s own structure, and cited by edition, table and page. Publishers' typeset tables and figures are not reproduced. A record may carry an open item while a value is untranscribed; the release gate fails on any. The registry below is rendered from the library.

A new edition, an annual index update or a standards revision enters the library by superseding, never by overwriting: an issued estimate keeps computing on the records it names. Second reads and open items are listed in the library changelog.

What it deliberately does not do

Questions

Write to hello@infertic.com. The product is built by Vantis Project Intelligence Ltd.