# 1.2 Machine learning lecture 3  (Page 2/14)

You can actually take this even further, right? Which is – let’s see. I have seven training examples here, so you can actually maybe fit up to six for the polynomial. You can actually fill a model theta zero plus theta one, X1 plus theta two, X squared plus up to theta six. X to the power of six and theta six are the polynomial to these seven data points. And if you do that you find that you come up with a model that fits your data exactly. This is where, I guess, in this example I drew, we have seven data points, so if you fit a six model polynomial you can, sort of, fit a line that passes through these seven points perfectly. And you probably find that the curve you get will look something like that. And on the one hand, this is a great model in a sense that it fits your training data perfectly. On the other hand, this is probably not a very good model in the sense that none of us seriously think that this is a very good predictor of housing prices as a function of the size of the house, right?

So we’ll actually come back to this later. It turns out of the models we have here; I feel like maybe the quadratic model fits the data best. Whereas the linear model looks like there’s actually a bit of a quadratic component in this data that the linear function is not capturing. So we’ll actually come back to this a little bit later and talk about the problems associated with fitting models that are either too simple, use two small a set of features, or on the models that are too complex and maybe use too large a set of features. Just to give these a name, we call this the problem of underfitting and, very informally, this refers to a setting where there are obvious patterns that – where there are patterns in the data that the algorithm is just failing to fit. And this problem here we refer to as overfitting and, again, very informally, this is when the algorithm is fitting the idiosyncrasies of this specific data set, right? It just so happens that of the seven houses we sampled in Portland, or wherever you collect data from, that house happens to be a bit more expensive, that house happened on the less expensive, and by fitting six for the polynomial we’re, sort of, fitting the idiosyncratic properties of this data set, rather than the true underlying trends of how housing prices vary as the function of the size of house. Okay?

#### Questions & Answers

where we get a research paper on Nano chemistry....?
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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