LFD Book Forum  

Go Back   LFD Book Forum > Book Feedback - Learning From Data > Chapter 1 - The Learning Problem

Reply
 
Thread Tools Display Modes
  #1  
Old 04-17-2012, 03:39 AM
rohanag rohanag is offline
Invited Guest
 
Join Date: Apr 2012
Posts: 94
Default question target distribution

In the lectures, we take a deterministic target function and add noise to it to make a target distribution. This is what we have done in the programming assignment too. But is it advisable to introduce noise in a data set which is handed to you? Maybe the data set handed over to you already has noise, maybe not?

One more question, in the lecture, we said noise = y - f(x) ,
Noisy target = deterministic target f(x) = E(y|x) + Noise (y - f(x) )

I do not get the above equation, shouldn't
Noisy target = deterministic target + Noise
Noisy target = f(x) + Noise ( y - f(x) )
Noisy target = y

This is really confusing me.
Reply With Quote
  #2  
Old 04-17-2012, 02:02 PM
cnknd cnknd is offline
Junior Member
 
Join Date: Apr 2012
Posts: 2
Default Re: question target distribution

My understanding is that Noisy target = y, but we want to decompose this noisy target into the deterministic component and the noise. The equations from the lectures simply measure the noise component as the difference between the noisy target and the deterministic target (i.e. y - f(x)). We can't really say much more about what the noise is because it depends on the situation in which you're applying the learning algorithm.

As for the examples in the lectures and the assignment where we have to add noise to a deterministic target function, we're only doing so because the sample data that we generated are from the deterministic target function and would therefore not contain any noise. But I don't think any real world situations would present a training set with no noise. We need to manually add noise to the "ideal" data we generated ourselves in order to mimic real world data.
Reply With Quote
Reply

Tags
target distribution

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 06:35 AM.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
The contents of this forum are to be used ONLY by readers of the Learning From Data book by Yaser S. Abu-Mostafa, Malik Magdon-Ismail, and Hsuan-Tien Lin, and participants in the Learning From Data MOOC by Yaser S. Abu-Mostafa. No part of these contents is to be communicated or made accessible to ANY other person or entity.