400 search results for "evaluation"

Spatial Randomness Evaluation in R: Monte Carlo Test

May 14, 2012
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Spatial Randomness Evaluation in R: Monte Carlo Test

This post is a some kind of reply to this one.So our goal is to determine whether our point process is random or not. We will use R and spatstat package in particular. Spatstat provides a very handy function for this, that uses K-function combined with...

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Are students’ teaching evaluations influenced by instructors’ looks?

August 3, 2011
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Are students’ teaching evaluations influenced by instructors’ looks?

Are students' teaching evaluations influenced by instructors' looks? ggplot2 may help find the answer.The recent release of RcmdrPlugin.KMggplot2 has made ggplot2 available to those who prefer GUI to the command line interface. With the new plugin for ...

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Forecast estimation, evaluation and transformation

November 9, 2010
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Forecast estimation, evaluation and transformation

I’ve had a few emails lately about forecast evaluation and estimation criteria. Here is one I received today, along with some comments. I have a rather simple question regarding the use of MSE as opposed to MAD and MAPE. If the parameters of a time series model are estimated by minimizing MSE, why do we

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RSI(2) Evaluation

June 28, 2009
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RSI(2) Evaluation

Despite my best efforts, it's been a month since the last post of this series. The first post replicated this simple RSI(2) strategy from the MarketSci Blog using R. The second post showed how to replicate the strategy that scales in/out of RSI(2). ...

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Predicting Titanic deaths on Kaggle IV: random forest revisited

August 23, 2015
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Predicting Titanic deaths on Kaggle IV: random forest revisited

On July 19th I used randomForest to predict the deaths on Titanic in the Kaggle competition. Subsequently I found that both bagging and boosting gave better predictions than randomForest. This I found somewhat unsatisfactory, hence I am now revisi...

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Is Bayesian A/B Testing Immune to Peeking? Not Exactly

August 20, 2015
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Is Bayesian A/B Testing Immune to Peeking? Not Exactly

Since I joined Stack Exchange as a Data Scientist in June, one of my first projects has been reconsidering the A/B testing system used to evaluate new features and changes to the site. Our current approach relies on computing a p-value to measure our confidence in a new feature. Unfortunately, this leads to a common pitfall in performing A/B...

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Evaluating Logistic Regression Models

August 17, 2015
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Evaluating Logistic Regression Models

Logistic regression is a technique that is well suited for examining the relationship between a categorical response variable and one or more categorical or continuous predictor variables. The model is generally presented in the following format, where β refers to the parameters and x represents the independent variables. log(odds)=β0+β1∗x1+...+βn∗xn The log(odds), or log-odds ratio, is defined

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How Do You Know if Your Data Has Signal?

August 10, 2015
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How Do You Know if Your Data Has Signal?

Image by Liz Sullivan, Creative Commons. Source: Wikimedia An all too common approach to modeling in data science is to throw all possible variables at a modeling procedure and “let the algorithm sort it out.” This is tempting when you are not sure what are the true causes or predictors of the phenomenon you are … Continue reading...

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Predicting Titanic deaths on Kaggle III: Bagging

August 9, 2015
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Predicting Titanic deaths on Kaggle III: Bagging

This is the third post on prediction the deaths. The first one used randomforest, the second boosting (gbm). The aim of the third post was to use bagging. In contrast to the former posts I abandoned dplyr in this post. It gave some now you see now you ...

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Sensemaking in R: A Plenitude of Models Makes for Good Storytelling

August 3, 2015
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Sensemaking in R: A Plenitude of Models Makes for Good Storytelling

"Sensemaking is a motivated, continuous effort to understand connections (which can be among people, places, and events) in order to anticipate their trajectories and act effectively."- Gary Klein, Brian Moon & Robert HoffmanMaking Sense of Sensema...

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