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So in the problem set we’re actually gonna let you play around more with this algorithm. So I won’t say too much more about it here. But to finally move on to the next topic let me check the questions you have. Yeah?

Student: It seems like you still have the same problem of overfitting and underfitting, like when you had a Q’s tow. Like you make it too small in your –

Instructor (Andrew Ng) :Yes, absolutely. Yes. So locally weighted regression can run into – locally weighted regression is not a penancier for the problem of overfitting or underfitting. You can still run into the same problems with locally weighted regression. What you just said about – and so some of these things I’ll leave you to discover for yourself in the homework problem. You’ll actually see what you just mentioned. Yeah?

Student: It almost seems like you’re not even thoroughly [inaudible] with this locally weighted, you had all the data that you originally had anyway.

Instructor (Andrew Ng) :Yeah.

Student: I’m just trying to think of [inaudible] the original data points.

Instructor (Andrew Ng) :Right. So the question is, sort of, this – it’s almost as if you’re not building a model, because you need the entire data set. And the other way of saying that is that this is a non-parametric learning algorithm. So this –I don’t know. I won’t debate whether, you know, are we really building a model or not. But this is a perfectly fine – so if I think when you write a code implementing locally weighted linear regression on the data set I think of that code as a whole – as building your model. So it actually uses – we’ve actually used this quite successfully to model, sort of, the dynamics of this autonomous helicopter this is. Yeah?

Student: I ask if this algorithm that learn the weights based on the data?

Instructor (Andrew Ng) :Learn what weights? Oh, the weights WI.

Student: Instead of using [inaudible].

Instructor (Andrew Ng) :I see, yes. So it turns out there are a few things you can do. One thing that is quite common is how to choose this band with parameter tow, right? As using the data. We’ll actually talk about that a bit later when we talk about model selection. Yes? One last question.

Student: I used [inaudible] Gaussian sometimes if you [inaudible]Gaussian and then –

Instructor (Andrew Ng) :Oh, I guess. Lt’s see. Boy. The weights are not random variables and it’s not, for the purpose of this algorithm, it is not useful to endow it with probable semantics. So you could choose to define things as Gaussian, but it, sort of, doesn’t lead anywhere. In fact, it turns out that I happened to choose this, sort of, bell-shaped function to define my weights. It’s actually fine to choose a function that doesn’t even integrate to one, that integrates to infinity, say, as you’re weighting function. So in that sense, I mean, you could force in the definition of a Gaussian, but it’s, sort of, not useful. Especially since you use other functions that integrate to infinity and don’t integrate to one. Okay? It’s the last question and let’s move on

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Machine learning. OpenStax CNX. Oct 14, 2013 Download for free at http://cnx.org/content/col11500/1.4
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