I'm a high school student trying to get into doing research for machine learning in the future and this resource seems promising to me as a way to get a more solid, foundational grasp in probability.
I'm not looking to unnecessarily min-max my learning or anything. I just want to know, is this actually a good resource to begin learning probability?
I'm a high school student trying to train a model that predicts early stage ORNJ (Osteoradionecrosis of the Jaw) based on patient data. For that, I'm trying to encode a scale for a patient's T stage and N stage.
So far, it's obvious that I can put T0-4 and N0-4 on a 0-4 scale. However, to my current understanding, I'm not sure where to put TX and NX.
I know that X means the tumor/spread for T and N respectively means they cant be assessed. But what does that mean exactly in terms of size/spread? Does it mean that X is so big/spread out that it cant be measured? Or does X indicate more of like a null/missing value where it can't be measured for some other reasons. If it's the latter, what are those potential reasons?
I really appreciate your time answering a simple question like this one :)
I'm a high-school student so I expect to be very far from correct just with what I know.
Concretely, when I think of what training an ML is like (particularly when training classical ML models on SKLearn), this is what I imagine the algorithm to ideally be:
To start, read the CSV and visualize the data (especially into a table if tabular and PCA to see patterns).
Drop rows with missing targets and columns that leak targets.
Do a train-test split into training and test data.
Construct a preprocessor as a column transformer for numerical and categorical variables.
Construct a model and parameter grid.
Construct a pipeline with the preprocessor and the model.
Do a grid search using a GridSearchCV estimator, passing in the pipeline, parameter grid, etc.
Choose the best hyper parameters to fit the model with them, then predict and evaluate it against the test data.
Its performance against the test data is how well it is likely to generalize to new data. Finish!
However, I feel like it would be naive to think this is always how it's done (perhaps it is though because this description is very general). But I want to know if this is missing anything? Any nuance? Is this not always how classical algorithms are trained? What are some distinct alternatives?
I hope I can use this post to be aware of what I don't know and understand my own limits. That way, I know what to learn next :)
im a cis guy so i'm really really sorry if my ignorance or privilege causes me to disrespect anyone in the community. I mean to ask out of real desire to understand.
my question comes from me realizing that i don't actually understand why someone would come to know if they were a man, a woman, or neither. but i figure that the transgender community would be a good group to learn this from.
to my knowledge, both these ideas are false (or at least incomplete/misleading):
people realize their gender because their feelings tell them a specific gender's roles/activity make them more comfortable.
people realize their gender because their feelings tell them that a specific gender's (or sex's) biological features make them more comfortable.
but these are untrue for two main reasons. using an example, a trans man doesn't need to be doing "masculine" things to feel and be a man. likewise the same trans man doesn't need to feel uncomfortable in their female body to feel and be a man. they just need to have that feeling that they are.
of course, i would say it's valid if either two (or a mix of both) were the reason someone identified with a certain gender. but this means to me that you dont need to want a gender's social or biological expression to identify as that gender.
ive seen an argument for the fact that the label of a gender itself can resonate with people and this is what decides for someone what they identify as. but i think that someone would only find a label resonating if they felt at least one of the ideas above, so i dont think labels itself are a standalone reason.
so what are the reasons someone has that help them conclude their gender? how could the trans man in the example realize that they're trans?
in other words, where does that feeling of "this is my gender" come from? and is there any specific theory/studied sense of understanding that i can learn about this more from?
thank you for answering in advanced :)
If I have a linear transformation T(x) = Ax, where A is a matrix and x is a vector, which object are we calling the "linear transformation"?
Is it just T, A, or Ax? Or a combination of the three?
I guess this is just mostly semantics (in fact I just defined the transformation to be T, but ironically my doubt still holds). My trouble is that in my own head T out of the three makes the most sense to be called the linear transformation, since T is a function (the process itself) and a transformation is intuitively a process.
Arguably though, Ax is also a candidate in my mind because it's mathematically equal to T when you input x. But it just seems weird to call the output a transformation.
Arguably also is that A counts because the matrix actually represents the transformation by mathematically storing where unit vectors i and j land.
The reason I'm asking is because I'm doubtful of whether to think of the cross product as a linear transformation (like I've read), when it seems more like the dual vector of the matrix of it (instead of some function, output, or matrix). But I think of the dot product as a linear transformation, so it seems that a linear transformation is the output?
High school student here. In, 3Blue1Brown's Essence of Linear Algebra, he teaches that a non square matrix is visually a linear transformation from one dimension to another. So, similar to how he teaches that the columns in a square matrix indicate where the unit vectors i, j, k, etc. land, so is true for non-square matrices also.
My confusion lies in the visual and mathematical differences between some matrices.
Consider the matrix [[2, 1], [0, 0]. This can be considered as a linear transformation that shifts the unit vectors i to [2, 0] and j to [1, 0]. Visually, this collapses the plane grid to a line.
But a similar-looking transformation can be made with the matrix [[2], [1]]. In fact, I imagine they'd appear identical.
So what exactly is the difference between matrices like these? And is it wrong to conclude that their transformations geometrically look the same?
High school student here. I've come across Gauss' law for both electricity and magnetism and noticed that the amount of the field passing through a closed surface is found using the field strength for electrostatics, but the flux density for magnetism. So they're quite similar yet differently named.
Even colloquially, I hear that the magnetic flux density is informally referred to as the magnetic field in the same way that the electric field strength is informally referred to as the electric field.
Both seem to fundamentally describe their respective fields, so why are they named differently? Why isn't electric field strength called electric flux density (although I hear thats already taken by the "displacement vector") or magnetic flux density called magnetic field strength?
High school student here. I've read that the current in a capacitor in an RC circuit must be negative because the capacitor is losing charge. At first, it sounded very reasonable. But then I had a doubt.
If current is negative because a component is losing charge, then doesn't this imply current is positive because a component is gaining charge?
My issue is that this feels nonsensical. For instance, in a series circuit with a discharging capacitor and a resistor, the implication means that the resistor is gaining charge. But this doesn't make sense.
So how do I reconcile with the fact that the current in a capacitor is negative?
I am a high school student being taught uniform circular motion. Today, my teacher taught us that when a motorbike drifts to make a sharp turn, the bike tilts so that the centripetal force is provided by the normal contact force.
This confused me a bunch. Shouldn't it be friction? How can the normal contact force have a horizontal component? They explained that when an object tilts, so does the normal force. But everything I know and have read about normal forces says it must be perpendicular to the surface, so it always acts vertically up – that is correct by definition. But they say that it's not and weve been taught wrong.
However, I can't find any credible sources that back this up – just some Wikipedia, Stack Exchange, and Reddit articles. So how can I prove this definitively?
When I consider a car in uniform circular motion, I've read that when the wheels turn, a static frictional force acts perpendicular to the direction of the wheels. Because of this, it provides the centripetal force necessary to maintain that motion.
However, I don't understand that premise: how is it reasonable to say that the friction must be perpendicular to the wheels? Intuitively, it makes more sense to say that the frictional force would be against the velocity vector of the car, so what is the physics there?
Also, if the frictional force were perpendicular to the wheels, then it would not perpendicular to the velocity vector because the car and the wheels aren't aligned. Instead, it would be slightly downwards/obtuse to the velocity vector. This implies that there must be some kind of force that's slightly upwards/acute to the velocity vector to maintain constant velocity. So which force would that be?
I think this confusion is just because of my gap in knowledge about friction (considering I've read of the types of friction on a wheel while researching about this and I hardly get it), but I still can't understand. So, how does the frictional force end up perpendicular to velocity?
High school student here.
Currently, what I understand is that the TCP/IP protocol suite is a framework that outlines what protocols are used in the internet, how each protocol should work, and how each protocol should work together.
Each protocol works by enforcing a specific format for data being sent across a network to achieve a specific purpose. In TCP/IP, we group similar-in-purpose protocols into functional categories called layers.
The reason it's appropriate to call them layers is because the protocols work together by stringing together their headers so that it's like they're being "stacked" on top of each other.
In this way of understanding TCP/IP I feel that I can understand all the layers but one – the application layer.
For example, the transport layer (which is usually TCP) format enforces port addresses and a checksum in the message being sent to identify which processes are communicating with each other and for error detection.
But for the application layer (using HTTP as an example) format enforces metadata in ASCII, a body text when appropriate, etc. But how does this serve the function of the application layer? Which according to my syllabus is providing an interface of the network for the user. I fail to see the connection.
(P.S: I'm sorry for the big buildup of long text just for a simple question, I figure maybe it's important to explain my own understanding incase my misunderstanding in the general topic is affecting how I understand the application layer.)
To my understanding, by definition, the eccentricity of a conic section is the ratio of the distance between a locus point and a focus to the distance between a locus point and the directrix.
But for an ellipse, it can also be the ratio of the distance c between either foci and the center to the distance a between the vertex and the center.
I've scoured the internet for the answer but to no avail. So, how are these formulae connected?
Edit: made a typo about the definition of eccentricity haha, corrected it now.
My current thought process is that if I want to send a message to a device in another LAN, the destination IP address on the packets must be their routers public IP, since the device's IP is private. Once the packets arrive, the router forwards the packets to any device listening to the appropriate port.
However, this seems to imply that the router forwards the packet to multiple LAN devices, which I believe routers don't do; they forward the packet to the specific device I intended to send to. So is it right?
Or is the destination IP address the private IP of the device I wanted to send a message to? If so, how did my device get access to that non-visible, private IP?
High school student here.
In TCP/IP protocol suite, the MAC addresses are used in the link layer to send frames between devices in a LAN, ensuring that devices in the same LAN can communicate.
However, the router also assigns each LAN device with a private IP address. So how is that private IP needed? Certainly the MAC is sufficient for devices in the LAN to talk to each other, so is it for devices outside the LAN to send messages to that host? I have doubt about that, because if it's private, then no one across the internet should be able to access it. Correct?
So what is the private IP address for?
Doing AS Level Physics questions for high school, and it wants us to figure out the closest distance r an alpha particle with charge Q1 can get to some atomic nucleus with charge Q2. From what I've seen, all the kinetic energy is transferred to electric potential energy U, which by Coulombs law,
U = k * Q1Q2 / r
where k is the electrical constant.
but this equation assumes that the force exerted on alpha particle is the Coulomb force, which requires the point charge to be stationary, even though the alpha particle is being shot towards the nucleus
So why is Coulomb's law used and how is it valid? Will not the magnetic force affect the answer in some way?
High school student studying Computer Science for AS Levels. I'm struggling to understand how the internet protocol suite is applied to the internet.
Currently from what I understand, the TCP/IP layers are just different ways of viewing the same network, with the top of the stack being the highest level of abstraction.
Because of that, each layer essentially performs the "same" task of getting a message sent from one application on one device to another, however, the layers above depend on functions of the more concrete layers below to work. So, in the application layer, it's from the perspective of how the end users or software developers use network; in the transport layer, it's from the perspective of how applications use the network; in the internet layer, it's from the perspective of how the routers use the network; and in the link layer, it's from the perspective of how the directly-connected devices and media use the network.
At the same time, I'm also being taught that TCP/IP is just a stack of protocols layered on top of each other. Yet from my understanding the layers do much more than just represent the layers protocols?
Which is it? Abstraction layers or stack of protocols? I believe it's the first, but it begs the question. How are these layers implemented in practice? Is it just a lot of "API calls" from layer to layer? Or something else entirely?
Studying application layer protocols for high school computer science.
According to how I understand it, SMTP (Simple Mail Transfer Protocol) is a push protocol. Unlike a pull protocol (like POP3), an email is sent from client to server, instead of from server to client. Thus, it's a push protocol.
However, I'm reading that it's also about who initiates establishing the connection between server and client? As in, if the server initiates the connection, its push. Otherwise, it's pull.
I'm also reading that it's more about how often the client is connected to the server? As in, if they're always connected, it's push. Otherwise, it's pull.
But I don't understand, which of the 3 is right? Is there some larger idea that connects these ideas together? Also, if the protocol is connectionless, is it neither push nor pull? Lastly, in a peer to peer network, are there push or pull protocols? If so, how?
Note that I'm understanding this mainly off of SMTP, although I would like to know how push protocols function in general.
Hey guys :) I'm a co-founder of Project ReWear, a student-led initiative dedicated to reducing waste. We do this by collecting unused clothes and redistributing them within schools, universities, or communities. Incase you'd like to know, I'm a Year 12 student in Dubai (the workload is insane).
We want to find student ambassadors like us to expand.
In our first drive, we collected around 200 kg of clothes, preventing approximately 5,000 kg of CO2 emissions. We managed to do this in our school in just 2 weeks. After speaking to our principal, We’re now looking to expand across Dubai (and down the line, internationally) by recruiting ambassadors at other schools, universities, or communities.
As an ambassador, we need you to build your own team at your community, and run a clothing collection drive. Feel free to even leverage our proven results when pitching to your administration if you need to! You won’t be starting from scratch.
If you want push to for a greener earth, start where you are. We really need people who want to make real impact.
Check us out on instagram @proj.ectrewear If you or anyone you know would be interested!
Connecting two charged plates to a power supply, if I let some uncharged conductor touch one of the plates, will it immediately gain the same amount of potential as the plate? Or will it take some non-negligible amount of time? Why so/not?
I'm asking in context of a mechanical mouse trap. To set the trap, I need to pull down the lever 90 degrees, stretching a spring, before locking it in place.
If I want to figure out how much work is done on the spring, then I can model it so that the force F (which is exerted perpendicularly on the lever) I apply on the lever * the arc length that force is applied for is the work done on the spring.
However, since I am also doing work on the lever to tilt it down, is it a more accurate answer to take into account the GPE (gravitational potential energy) that the lever lost?
To do this, I can use the change in height of the lever's center of gravity * the weight of the lever, then add that to the work I had calculated earlier. This way, I can take into account the work done by the force I applied and the work done by gravity to stretch this spring.
My question though is if this is valid reasoning? Something doesn't sit right with me taking into account the GPE of the lever, even if its change was non-negligible.