When Variable Reduction Doesn’t Work

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Um bom exemplo de como os procedimentos habituais nem sempre funcionam

Summary: Exceptions sometimes make the best rules.  Here’s an example of well accepted variable reduction techniques resulting in an inferior model and a case for dramatically expanding the number of variables we start with.

of the things that keeps us data scientists on our toes is that the well-established rules-of-thumb don’t always work.  Certainly one of the most well-worn of these rules is the parsimonious model; always seek to create the best model with the fewest variables.  And woe to you who violate this rule.  Your model will over fit, include false random correlations, or at very least will just be judged to be slow and clunky.

Certainly this is a rule I embrace when building models so I was surprised and then delighted to find a well conducted study by Lexis/Nexis that lays out a case where this clearly isn’t true.

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Chance Lecture Video Series

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Bons vídeos ainda q antigos de alguns temas em probabilidade e estatística

This page has links to:

  • 2000 Chance Lecture Video Series
  • 1998 Chance Lecture Video Series
  • 1997 Chance Lecture Video Series
  • Chance Workshop Video Lectures
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    IFORS Education Resources Project

    portal com materal sobre Investigação Operacional, otimização e SADs

    portal com materal sobre Investigação Operacional, otimização e SADs

    Welcome to the International Federation of Operational Research Societies (IFORS) Education Resources Project

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    Dictionary of Numbers

    um dicionário q associa factos a números

    um dicionário q associa factos a números

    is an award-winning Google Chrome extension that tries to make sense of numbers you encounter on the web by giving you a description of that number in human terms. Like a dictionary describes words you don’t know in terms you do, Dictionary of Numbers puts quantities you’re unfamiliar with in terms you can understand. Because “8 million people” means nothing, but “population of New York City” means everything.

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    Punk Rock Operations Research

    Um blogue com modelos e aplicações de técnicas de IO

    Um blogue com modelos e aplicações de técnicas de IO

    Punk Rock Operations Research by Laura A. McLay is licensed under a Creative Commons Attribution-NonCommercial 3.0 United States License

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    VideoLectures.Net

    montes de vídeos sobre imensos temas

    montes de vídeos sobre imensos temas

    VideoLectures.NET is a free and open access educational video lectures repository. The lectures are given by distinguished scholars and scientists at the most important and prominent events like conferences, summer schools, workshops and science promotional events from many fields of Science. All lectures, accompanying documents, information and links are systematically selected and classified through the editorial process taking into account also users’ comments.

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    Linear Optimization with Applications

    Uma boa página sobre programação linear

    Uma boa página sobre programação linear

    1. Introduction & Summary
    2. Optimization-Modeling Process
    3. Ingredients of Optimization Problems and Their Classification
    4. Linear Programming (LP)
    5. Dual Problem: Its Construction and Economics Implications
    6. Learning From the Optimal Strategy
    7. Goal-Seeking Problem
    8. Exercise Your Knowledge to Enhance What You Have Learned (PDF)
    9. Linear Optimization Solvers to Download (free-of-charge),

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    The Science of Better

    OR The Science of Better

    what is O.R.?

    In a nutshell, operational research (O.R.) is the discipline of applying advanced analytical methods to help make better decisions.

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