90 useful models

Posted on by Brandon Klein


    (1) Systems Thinking — “By taking the overall system as well as its parts into account systems thinking is designed to avoid potentially contributing to further development of unintended consequences.” (related: causal loop diagrams, stock and flow, Le Chatelier’s principle, hysteresis — “the time-based dependence of a system’s output on present and past inputs.”)
    (1) Scenario Analysis — “A process of analyzing possible future events by considering alternative possible outcomes.”
    (1) Power-law — “A functional relationship between two quantities, where a relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one quantity varies as a power of another.” (related: Pareto distribution; Pareto principle — “for many events, roughly 80% of the effects come from 20% of the causes.”, diminishing returns, premature optimization, heavy-tailed distribution, fat-tailed distribution; long tail — “the portion of the distribution having a large number of occurrences far from the “head” or central part of the distribution.”; black swan theory — “a metaphor that describes an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight.”)
    (1) Normal Distribution — “A very common continuous probability distribution…Physical quantities that are expected to be the sum of many independent processes (such as measurement errors) often have distributions that are nearly normal.” (related: central limit theorem)
    (1) Sensitivity Analysis — “The study of how the uncertainty in the output of a mathematical model or system (numerical or otherwise) can be apportioned to different sources of uncertainty in its inputs.”
    (1) Cost-benefit Analysis — “A systematic approach to estimating the strengths and weaknesses of alternatives that satisfy transactions, activities or functional requirements for a business.” (related: net present value — “a measurement of the profitability of an undertaking that is calculated by subtracting the present values of cash outflows (including initial cost) from the present values of cash inflows over a period of time.”, discount rate)
    (3) Simulation — “The imitation of the operation of a real-world process or system over time.”
    (3) Pareto Efficiency — “A state of allocation of resources in which it is impossible to make any one individual better off without making at least one individual worse off…A Pareto improvement is defined to be a change to a different allocation that makes at least one individual better off without making any other individual worse off, given a certain initial allocation of goods among a set of individuals.”


    (1) Lateral Thinking — “Solving problems through an indirect and creative approach, using reasoning that is not immediately obvious and involving ideas that may not be obtainable by using only traditional step-by-step logic.”
    (1) Divergent Thinking vs Convergent Thinking — “Divergent thinking is a thought process or method used to generate creative ideas by exploring many possible solutions. It is often used in conjunction with its cognitive opposite, convergent thinking, which follows a particular set of logical steps to arrive at one solution, which in some cases is a ‘correct’ solution.” (related: groupthink)
    (2) Critical Mass — “The smallest amount of fissile material needed for a sustained nuclear chain reaction.” “In social dynamics, critical mass is a sufficient number of adopters of an innovation in a social system so that the rate of adoption becomes self-sustaining and creates further growth.”
    (2) Activation Energy — “The minimum energy which must be available to a chemical system with potential reactants to result in a chemical reaction.”
    (2) Catalyst — “A substance which increases the rate of a chemical reaction.”
    (2) Leverage — “The force amplification achieved by using a tool, mechanical device or machine system.”
    (2) Crowdsourcing — “The process of obtaining needed services, ideas, or content by soliciting contributions from a large group of people, especially an online community, rather than from employees or suppliers.” (related: wisdom of the crowd — “a large group’s aggregated answers to questions involving quantity estimation, general world knowledge, and spatial reasoning has generally been found to be as good as, and often better than, the answer given by any of the individuals within the group.”, collective intelligence)
    (3) The Structure of Scientific Revolutions — “An episodic model in which periods of such conceptual continuity in normal science were interrupted by periods of revolutionary science. The discovery of “anomalies” during revolutions in science leads to new paradigms. New paradigms then ask new questions of old data, move beyond the mere “puzzle-solving” of the previous paradigm, change the rules of the game and the “map” directing new research.” (related: Planck’s principle — “the view that scientific change does not occur because individual scientists change their mind, but rather that successive generations of scientists have different views.”)


    (1) Scientific Method — “Systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.” (related: reproducibility)
    (1) Proxy — “A variable that is not in itself directly relevant, but that serves in place of an unobservable or immeasurable variable. In order for a variable to be a good proxy, it must have a close correlation, not necessarily linear, with the variable of interest.” (related: revealed preference)
    (1) Selection Bias — “The selection of individuals, groups or data for analysis in such a way that proper randomization is not achieved, thereby ensuring that the sample obtained is not representative of the population intended to be analyzed.” (related: sampling bias)
    (1) Response Bias — “A wide range of cognitive biases that influence the responses of participants away from an accurate or truthful response.”
    (2) Observer Effect — “Chang