Line 59: Line 59:
 
== Questions and comments==
 
== Questions and comments==
  
If you have any questions, comments, etc. please post them On [[Upper_Bounds_for_Bayes_Error_Questions_and_comment|this page]].
+
If you have any questions, comments, etc. please post them On [[Bayes_Rule_for_Minimizing_Risk_Questions_and_comment|this page]].

Revision as of 14:03, 12 April 2014


Bayes Error for Minimizing Risk
A slecture by ECE student Dennis Lee

Partly based on the ECE662 Spring 2014 lecture material of Prof. Mireille Boutin.


Introduction


Bayes rule for minimizing risk


Example 1: 1D features


Example 2: 2D features

Fig 1: Data for class 1 (crosses) and class 2 (circles). In all cases, Prob($ \omega_1 $) = Prob($ \omega_2 $) = 0.5. Misclassified points are shown in red. Values of $ \mu_1 $, $ \mu_2 $, and $ \Sigma $ are given in Eqs. (------) - (----------). As the figures show, the separating hyperplanes shift depending on the values of $ c_{12} $ and $ c_{21} $.

Summary and Conclusions

In this lecture we have shown that the probability of error ($Prob \left[ Error \right] $) when using Bayes error, is upper bounded by the Chernoff Bound. Therefore,

$ Prob \left[ Error \right] \leq \varepsilon_{\beta} $

for $ \beta \in \left[ 0, 1 \right] $.

When $ \beta =\frac{1}{2} $ then $ \varepsilon_{\frac{1}{2}} $ in known as the Bhattacharyya bound.


References

[1]. Duda, Richard O. and Hart, Peter E. and Stork, David G., "Pattern Classication (2nd Edition)," Wiley-Interscience, 2000.

[2]. Mireille Boutin, "ECE662: Statistical Pattern Recognition and Decision Making Processes," Purdue University, Spring 2014.


Questions and comments

If you have any questions, comments, etc. please post them On this page.

Alumni Liaison

Basic linear algebra uncovers and clarifies very important geometry and algebra.

Dr. Paul Garrett