A powerful, easy-to-use multi-criteria decision and evaluation tool

If you make decisions using numbers you need Tetra

What is Tetra?

Tetra is the only software for evaluation, measurement and decision making that is based on sound mathematical foundations.

Why is it needed?

There are logical and mathematical errors at the foundations of decision theory, game theory, economic theory, psychology, and other social science disciplines — see Mathematical Foundations of Decision Theory. These errors can be avoided by using Tetra.

How does it work?

Tetra constructs preference scales using a user’s (or users’) criteria weights and alternatives’ ratings.

  • The user specifies the alternatives to be considered, the criteria and sub-criteria on which the alternatives are rated.
  • Alternatives are rated on the criteria in a simple and intuitive manner and the criteria are weighted by their relative importance.
  • Tetra then rates the alternatives on a scale that takes into account all these pieces of information.

Tetra is easy-to-use, intuitive, and powerful. No mathematical knowledge is required from the user (the heavy math is “under the hood”).

Tetra is also available as a service (SaaS). Contact us for details.



NEW: Spectral Algorithm

NEW: Linear Equations Challenge

Supply and Demand Equilibrium and Debreu’s Theory of Value

Economic Theory’s Curves

Demand, Barter, and Exchange

And the Math is Incorrect

The Foundations

Decision Theory

Utility Theory


Download Tetra

Tetra Quickstart Guide

Tetra Online Documentation




An Elementary Demand Theory Error

Ordinal Utility and Indifference Curves

Von Neumann's Error

Game Theory: Whose Values?