Posts tagged with ‘R’

  • Netflix Prize and Injury Prediction Prize

    By Mladen Jovanovic on 13/03/2017

    The Netflix Prize was an open competition for the best collaborative filtering algorithm to predict user ratings for films, based on previous ratings without any other information about the users or films, i.e. without the users or the films being identified except by numbers assigned for the contest. Which made me think – why don’t the “rich” clubs, such...

  • Thoughts on Injury Prediction

    By Mladen Jovanovic on 08/12/2016

    In the following article, I am discussing the famous “J” curve in injury prediction, as well as simulate some data to show how that curve is estimated. I also show the distinction between association and prediction, as well as how to make training decisions based on the different costs of committing false positive and false negative errors.

  • The Dowry Problem

    By Mladen Jovanovic on 18/10/2016

    In this video I am solving the famous dowry problem using the simulation in R. It is interesting to see how we can test the assumptions and heuristic easily with simulations.

  • Individualizing Training Using Clustering Algorithms

    By Mladen Jovanovic on 10/06/2016

    The goal of this blog post is to present simple solution to “grouping” individuals based on their needs, characteristics and/or goals.

  • Masked Relationships and Multicollinearity

    By Mladen Jovanovic on 04/05/2016

    In this video and R workbook I am “playing” with linear regression and I am trying to explain the concept of “controlling” for one variable (this is common in statistics, but I had hard time understanding it until I visualized the problem), masked relationships and multicollinearity.

  • [Playbook] Converting Just Jump to Smart Jump

    By Mladen Jovanovic on 23/04/2016

    Coaches and athletes sometime change measurement/testing equipment. The problem is that the estimates from different equipment might differ (and they usually do). There are couple of soutions to this problem...

  • What Is Propensity Matching and How Can We Improve Validity of Causality Claims?

    By Mladen Jovanovic on 19/03/2016

    Researchers usually try to randomize correctly, but sometimes the effect is not in the treatment, but maybe in the difference between group (pre-treatment) or during the treatment (for example volume of training) which should be similar/same so we can judge the effects of something else of interest (for example novel periodization). The solutions are to involve covariates in the…

  • R Playbook: Injury Prediction using Random Forest

    By Mladen Jovanovic on 02/11/2015

    This is the problem I have been wrestling with for some time and I tried to solve it using Bannister model. I even asked for help on Twitter and couple of data scientists suggested taking a look into “functional data analysis” or creating summary variables and performing regression/classification (which I did here).

  • Workbook: Change Point Analysis of HRV Data

    By Mladen Jovanovic on 02/08/2015

    What is Change Point Analysis and why and how can you use it to help you out to make sense of your monitoring data? Find out more….

  • R Playbook: Introduction to Multilevel/Hierarchical Models

    By Mladen Jovanovic on 09/07/2015

    I wrote about mixed-level models before and I want to expand on it here. I sort-of finished Andrew Gelman’s Data Analysis Using Regression and Multilevel/Hierarchical Models and will continue to play with it. As far as I know Andrew uses the term multilevel models and avoids the terms fixed and random effect. This is a great book to have.

    My…

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