# 1.4 Machine learning lecture 5  (Page 9/15)

And it turns out, generative learning algorithms often do surprisingly well even when these modeling assumptions are not met, but one other tradeoff is that by making stronger assumptions about the data, Gaussian discriminant analysis often needs less data in order to fit, like, an okay model, even if there’s less training data.

Whereas, in contrast, logistic regression by making less assumption is more robust to your modeling assumptions because you’re making a weaker assumption; you’re making less assumptions, but sometimes it takes a slightly larger training set to fit than Gaussian discriminant analysis. Question?

Student: In order to meet any assumption about the number [inaudible], plus here we assume that PFY = 1, equal two number of. [Inaudible]. Is true when the number of samples is marginal?

Instructor (Andrew Ng) :Okay. So let’s see. So there’s a question of is this true – what was that? Let me translate that differently. So the marving assumptions are made independently of the size of your training set, right? So, like, in least/great regression – well, in all of these models I’m assuming that these are random variables flowing from some distribution, and then, finally, I’m giving a single training set and that as for the parameters of the distribution, right?

Student: So what’s the probability of Y = 1?

Instructor (Andrew Ng) :Probability of Y + 1?

Student: Yeah, you used the –

Instructor (Andrew Ng) :Sort of, this like – back to the philosophy of mass molecular estimation, right? I’m assuming that they’re PFY is equal to phi to the Y, Y - phi to the Y or Y - Y. So I’m assuming that there’s some true value of Y generating all my data, and then – well, when I write this, I guess, maybe what I should write isn’t – so when I write this, I guess there are already two values of phi. One is there’s a true underlying value of phi that guards the use to generate the data, and then there’s the maximum likelihood estimate of the value of phi, and so when I was writing those formulas earlier, those formulas are writing for phi, and mew0, and mew1 were really the maximum likelihood estimates for phi, mew0, and mew1, and that’s different from the true underlying values of phi, mew0, and mew1, but –

Student: [Off mic].

Instructor (Andrew Ng) :Yeah, right. So maximum likelihood estimate comes from the data, and there’s some, sort of, true underlying value of phi that I’m trying to estimate, and my maximum likelihood estimate is my attempt to estimate the true value, but, you know, by notational and convention often are just right as that as well without bothering to distinguish between the maximum likelihood value and the true underlying value that I’m assuming is out there, and that I’m only hoping to estimate.

Actually, yeah, so for the sample of questions like these about maximum likelihood and so on, I hope to tease to the Friday discussion section as a good time to ask questions about, sort of, probabilistic definitions like these as well. Are there any other questions? No, great. Okay.

can someone help me with some logarithmic and exponential equations.
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
a perfect square v²+2v+_
kkk nice
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
rolling four fair dice and getting an even number an all four dice
Kristine 2*2*2=8
Differences Between Laspeyres and Paasche Indices
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
is it 3×y ?
J, combine like terms 7x-4y
im not good at math so would this help me
yes
Asali
I'm not good at math so would you help me
Samantha
what is the problem that i will help you to self with?
Asali
how do you translate this in Algebraic Expressions
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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