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# Prediction Accuracy And Error Measures

## Contents

However, it can be very time consuming to implement. Figure 2.18: Forecasts of the Dow Jones Index from 16 July 1994. Many modeling procedures directly minimize the MSE.Mean Absolute Error (MAE) is similar to the Mean Squared Error, but it uses absolute values instead of squaring. credit rating? check my blog

Rule Induction: Sequential Covering Method 43  Sequential covering algorithm: Extracts rules directly from training data  Typical sequential covering algorithms: FOIL, AQ, CN2, RIPPER  Rules are learned sequentially, each yes no yes excellent fair no no yes yes  Example: Rule extraction from our buys_computer decision-tree IF age = young AND student = no THEN buys_computer = no IF age Chapman & Hall, 1990.  G. EDBT'96.  T. http://scott.fortmann-roe.com/docs/MeasuringError.html

## Prediction Error Definition

The mirror situation is typified by lenders who wish to cram as many bad loans as possible into the worst 10% of their file. Australasian Journal of Information Systems 5(1): 30–44.CrossRefGoogle ScholarLokan C. (2005). M. With this measure, positive errors cancel out negative ones.

The system returned: (22) Invalid argument The remote host or network may be down. Evaluating Classifier Accuracy: Bootstrap  Bootstrap  Works well with small data sets  Samples the given training tuples uniformly with replacement  i.e., each time a tuple is selected, it Understanding the Bias-Variance Tradeoff is important when making these decisions. Prediction Accuracy Measure The American Statistician, 43(4), 279-282.↩ Although adjusted R2 does not have the same statistical definition of R2 (the fraction of squared error explained by the model over the null), it is

A. Prediction Error Statistics Classification: Basic Concepts  Classification: Basic Concepts  Decision Tree Induction  Bayes Classification Methods  Rule-Based Classification  Model Evaluation and Selection  Techniques to Improve Classification Accuracy: Ensemble Methods K. The second section of this work will look at a variety of techniques to accurately estimate the model's true prediction error.

Classification: Basic Concepts  Classification: Basic Concepts  Decision Tree Induction  Bayes Classification Methods  Rule-Based Classification  Model Evaluation and Selection  Techniques to Improve Classification Accuracy: Ensemble Methods Prediction Error Psychology Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Model Evaluation and Selection  Evaluation metrics: How can we measure accuracy? At these high levels of complexity, the additional complexity we are adding helps us fit our training data, but it causes the model to do a worse job of predicting new

## Prediction Error Statistics

VLDB’96.  J. Tibshirani, and J. Prediction Error Definition Adjusted R2 is much better than regular R2 and due to this fact, it should always be used in place of regular R2. Prediction Error Formula Visualization of a Decision Tree in SGI/MineSet 3.0 September 14, 2014 Data Mining: Concepts and Techniques 28 28.

D has 9 tuples in buys_computer = “yes” and 5 in “no” 0.459 2 2 5 gini D = - æ ö çè æ - ÷ø ö 14 çè ( ) click site Sometimes, different accuracy measures will lead to different results as to which forecast method is best. What should you optimize when building an estimation model? The use of this incorrect error measure can lead to the selection of an inferior and inaccurate model. Prediction Error Regression

These squared errors are summed and the result is compared to the sum of the squared errors generated using the null model. Schapire. Please try the request again. news O.

Robust regression for developing software estimation models. Prediction Error Calculator Han, and C.-W. International Journal of Forecasting 8(1): 69–80.CrossRefGoogle ScholarDesharnais J (1989).

## Unsupervised Learning  Supervised learning (classification)  Supervision: The training data (observations, measurements, etc.) are accompanied by labels indicating the class of the observations  New data is classified based on

It is helpful to illustrate this fact with an equation. M. A common mistake is to create a holdout set, train a model, test it on the holdout set, and then adjust the model in an iterative process. How To Calculate Prediction Error Tan, M.

As defined, the model's true prediction error is how well the model will predict for new data. be non-zero. In fact, adjusted R2 generally under-penalizes complexity. http://bsdupdates.com/prediction-error/prediction-error-variance.php Fast effective rule induction.

We could use stock prices on January 1st, 1990 for a now bankrupt company, and the error would go down. C4.5: Programs for Machine Learning. that X is 31..40, medium income 32. 33 Prediction Based on Bayes’ Theorem  Given training data X, posteriori probability of a hypothesis H, P(H|X), follows the Bayes’ theorem X X Cong, K.-L.

Home Books Authors AboutOur vision OTexts for readers OTexts for authors Who we are Book citation Frequently asked questions Feedback and requests Contact Donation Search form Search You are hereHome » Fortunately, there exists a whole separate set of methods to measure error that do not make these assumptions and instead use the data itself to estimate the true prediction error. J. M.

Despite the existence of a bewildering array of performance measures, much commercial modeling software provides a surprisingly limited range of options. Han. Presentation of Classification Results September 14, 2014 Data Mining: Concepts and Techniques 27 27. University of Montreal.Foss T, Stensrud E, Kitchenham B and Myrtveit I (2003).

Commonly, R2 is only applied as a measure of training error. Preventing overfitting is a key to building robust and accurate prediction models. The size of the test set should ideally be at least as large as the maximum forecast horizon required. Here we initially split our data into two groups.

Yu, Direct Discriminative Pattern Mining for Effective Classification, ICDE'08  W. Yan, J. That is, it is invalid to look at how well a model fits the historical data; the accuracy of forecasts can only be determined by considering how well a model performs References (1)  C.

Share Email Chapter - 6 Data Mining Concepts an... K. As can be seen, cross-validation is very similar to the holdout method. This is quite a troubling result, and this procedure is not an uncommon one but clearly leads to incredibly misleading results.