/sqt/ - stupid questions thread

How do I find out wether this is normal distribution (in excel) ?

Other urls found in this thread:

en.wikipedia.org/wiki/Normality_test
1728.org/kepler3a.htm
math.columbia.edu/~woit/
math.columbia.edu/~woit/QM/qmbook.pdf
en.wikipedia.org/wiki/Quaternion
gamelab.mit.edu/games/a-slower-speed-of-light/
youtube.com/watch?v=KMwhGE0vd-w
bbc.co.uk/news/technology-36494150
google.com/#q=random molecules in something do some polar shit and it causes them to all line up or attract
chemistry.stackexchange.com/questions/1289/how-do-non-polar-substances-dissolve-in-non-polar-solvents
en.wikipedia.org/wiki/Two-mass-skate_bicycle
twitter.com/SFWRedditImages

Take mean, median and mode. Are they all the same? Its normal because central limit theorem.
Chi-square goodness-of-fit test to see if it's a normal distribution.
Whatever other unneccessary tests you wanna try.

Compute

m := E[x]
v := E[(m-x)^2]

and plot

C · exp(-(m-x)^2/2v)

for the C that makes the quadratic error the smallest and you got yourself a Gaussian fit

en.wikipedia.org/wiki/Normality_test

but to be real for a second: normality tests are almost entirely useless. any real-world situation where you might want to perform a normality test, you're either going to find that it's definitely not normal (which is probably an obvious result) or that it's close enough to normal that no one will ever give a shit if you just assume normality

during the biographical parts of my big TOE, did Tom eliminate substances in order to achieve altered states or just to make sure that nothing could fuck with his research?
The way he describes cutting off alcohol, drugs, and food additives is unclear.

when you inhale a strong scent, why does the exhale never have a scent to others?

>never
i am sure never is a strong word, but it's most certainly diminished

there is olphactory neurons in your nose mucosa that actually chemically might break down some of the smell chemicals, also, they probably get stuck around your respiratory path in other ways

>I don't want to turn Veeky Forums into my personal homework help, but I've been getting confused with the statistics for my dissertation and my supervisor is a fucking idiot qualitative researcher who just shrugs and ignores me whenever I ask him for help, so wondering if anyone could help me out

I used a questionnaire to measure a certain personality construct (X), which can either be conceptualised as a single higher-order construct or five separate facets (X1, X2... X5). My results show low intercorrelations between these facets, so I think it's best to go with them rather than the higher-order construct. Scores for each of these are on a continuous scale between 1 and 7.

I want to see if any of these are associated with performance at two timepoints (Y1, Y2), also measured on a continuous scale. Furthermore, I've also measured the use of two techniques (Z1, Z2), also on a continuous scale. Oh, and just in case it wasn't complicated enough already, I also have a covariate (C) which is likely to have the greatest impact on Y1 and Y2.

Basically, what I want to find out is (a) whether X1, X2, X3, X4 and/or X5 are associated with high performance at Y1 and Y2 (after controlling for C), and (b) whether Z1 and/or Z2 mediate this effect.

(1/2)

However, my data isn't being too kind to me and I'm getting fucking confused trying to work it out. For the first hypothesis, I tried two multiple linear regression models with Y1 or Y2 as the outcome variable, and then having C as my first predictor 'block', then X1, X2, X3, X4 and X5 as additional predictors in the second block. Both times, the ANOVA for the overall model, but none of the individual predictors were significant. Anyone know why this has happened and what I should do next? Should I report it as an insignificant finding, or is it weak but significant? Or have I likely made some mistake somewhere that I need to correct?

I thought maybe I was making it too complicated, so just loaded all of my variables into a correlation matrix to try and understand the data better. This made a bit more sense, and I found some of the expected results (e.g. C was strongly correlated with Y1 and Y2 - Z1 and Z2 were correlated with Y1, Z1 only was correlated with Y2 - X4 and X5 were correlated with Y1, X3 and X5 were correlated with Y2). I now have a general idea of what's going on, but is this enough in terms of statistical analysis? Would I need to do any further tests in order to return to my original hypotheses?

Thanks in advance for any help on this, because I'm really confused and the staff at my university are fucking useless and refuse to help. I'm convinced that there is some easy method to do this, but it goes beyond the scope of what I learned in my stats modules, and at the moment I'm stuck.

(2/2)

Guy who is too retarded to do the math himself here.

Could you use a cannon on the moon to shoot something into orbit?
I suppose the answer is yes. If so, how big does that cannon/gun has to be?
Lets assume a 200kg orbiter here.
Could it get into orbit without additional maneuvers? Could you shoot it in a way, that it will safely return to earth?

No. You can't get it to orbit because any unpropelled object will have a trajectory that passes through to its original location(In a 1 body system). But you can get it to earth I believe.

Anyone know where I could download a PDF copy of Physics in Minutes by Giles Sparrow? I've looked everywhere but can't seem to find it....

buy it

Also, I would say that many (smelly) chemicals will get into your metabolism so extinction will happen with a delay and over a longer period of time. Sulfides (which are what makes rotten eggs smell) are systemic.

What's the point of localization? (Commutative Algebra) What problem motivated the definition?

you could use a cannon that shoots a smaller cannon that puts the object into orbit

fucking vapers

Oh shit. I kind forgot about this problem. But if I shot it from a tower on the biggest mountain of the moon, I'm sure this wouldnt be a problem.
So how much of a gun do I need? Or better: what would be the orbital velocity I would need to archieve in a single impulse?

1728.org/kepler3a.htm

i wish i could, but i can't order from ebay or amazon, nor can i buy it in my country, so i'm fucked, it's neither expensive nor anything

thanks

Can someone explain to me the meaning of this sentence?

"I don't believe in empirical science. I only believe in a priori truth."

"I am a cunt"
Took me 4 years of grad school to decipher that one, lemme tell ya.

I've got a wisdom tooth coming in on the top left side of my mouth and it's starting to be a bother. While it was growing in, it didn't really stick out or hurt, but now that it's basically done, I'm feeling some irritation. Is it okay to leave it be, or am I gonna have to get it removed?

Go to a dentist.
He'll probably order an X-ray and later analyze it.
Each case is different. Don't gamble with your health.

Cartesianism.

Okay dad...

I'm not sure how to word this, but I've seen other people make the same observation that I have: math and physics books tend to be written in different styles.

All the math textbooks I've read in undergrad (with the exception of non-rigorous calculus) are very careful about what is an axiom/definition/assumption vs theorem, and how one thing follows from the next. Before throwing out an equation, it is always careful to frame things: "Let G be a group, suppose H is a normal subgroup of G, ... "

On the other hand, physics books (in my limited experience) tend to just throw around equations with lots of variables and integrals over various volumes with little explanation. I'm not saying I don't know what each symbol means, but it can get confusing to follow the logic along, and leaves me feeling a bit more shaky than with math.

Does anyone know of physics books that are written in a style more friendly to math students? Particularly quantum mechanics, but knowing EM and classical mechanics books like this would be good too.

is the wiki page not clear enough? it comes from the geometry but becomes formalized into a universal property

test&*&*(

I'm not too knowledgeable on this butyou might want to look for books/notes written by people on the math/physics interface, i.e. someone like Peter Woit

math.columbia.edu/~woit/
math.columbia.edu/~woit/QM/qmbook.pdf

Why is it that poor people reproduce so much more than wealthy people? You would think it would be the opposite since they already have it hard enough without the added complication of added mouths to feed. I know if I asked /pol/ they would probably say something about welfare checks but you see the same thing in developing nations without any such systems in place so that can't be all it is, and a Veeky Forums answer would be more interesting.

>they would probably
Go ask /pol/ faggot. There some cross posters there. But over there they can espouse their political incorrect views.

My professor posed the following question:

"How many integer non-negative solutions are there to x1 + x2 + x3 +
x4 + x5 = 28? what if we assume that all solutions are positive?"

I understand the first question and know that it is C(32,28) or 35,960, but does anyone know what he means by assume all solutions are positive?

he means now you should also exclude zero as a possible value for the x_i to take.

Oh gotcha. I thought maybe that's what he meant, but just wanted to make sure. Thanks

Is it safe to say that Galois' work that gave the connection between intermediate field extensions L/M/K and subgroups of Gal(L/K) was the first problem solved by looking at it through a sort of different mathematical lens/transferring what is trying to be solved to a very different setting? Kind of hard to word but I hope I'm getting my question across, it just seems like he genuinely had a revolutionary way of thinking

How does carrier mediated transport work to eliminate a drug? In the notes I took I wrote that the process is essentially only active if the drug is a substrate for carriers. I know that's wrong, hit please explain?

fags on g were too retarded to help me and this is beyond my maths knowledge or interest. However, I need it for a coding project of mine.

let's say a point O with a direction (probably just a unit vector I guess) as a 4x4 matrix. (3 angles and translation vector).
now I have a second vector v that points from O to a point P.
now I rotate O by some arbitrary direction.
if I now multiply v with the rotation Quaternion of O do I get the rotated vector v~?

h-help?

...

By the way I've never taken any form of class relating to this. I know how the drug is active or passive depending on if it's energized but how does it work to eliminate levels of a drug?

What method would you use to approach factoring something like a 27 term polynomial of some huge degree?

If it's a one-time thing, I'd look at the graph and start with Newton method at the (27 or less) best guesses

you're a fucktard and you should piss off to /g/.
your question doesnt even make sense and sounds like a lack of understanding some extremely fundamental things.

start reading here en.wikipedia.org/wiki/Quaternion

You need to re-phrase your question in coherent English.

>be me
>27 years old
>will be 28 on July 20th
>go to college orientation
>feel out of place
>everyone at orientation was around 17-22
>They all look like fucking children

Man, is this gonna be the longest 2-3 years of my life?

lets assume we know the kinetic energy of a bullet and this bullet impacts a target. The target isnt penetrated and it moves 1,2meters in 1,2 seconds. How can you figure out the mass of the target?.
I was thinking something like using the kinetic energy of the bullet and the speed at what the target moves (1m/s). Is this correct?

Here's what I'm getting from this.

You're trying to say that an object O is set at a particular location and orientation denoted by a 4x4 matrix in the vector space. There is a vector v that points from O to some point P. Now, changing the orientation of O in the vector space, you want to know how, mathematically, the vector v would change from the perspective of the reorienting object O. Right?

2 things missing.

Does the bullet bounce off of the target? Does the target slow to stopping in that 1.2 seconds or does it move at a constant speed after it's been hit?

Your intro classes will suck, higher level stuff will be fun though, especially if you're at a place where the classes get really small.

kinetic energy (KE) = (1/2)mv^2

At what velocity is the target moving initially? That gives you the value of v in the expression for how much KE it had to start with.

At what velocity is the target moving immediately after impact? That gives you the value of v in the expression for how much KE it had after the bullet hit.

The difference between those two is mow much KE is gained from the bullet, which is given to you. After plugging the bullet's KE and the values for v in, you should be left with only one variable, m, which you can solve for using algebra.

If I traveled faster than the speed of light, would I be running in darkness?

Don't listen to this fucker.
Shapiro-Wilk test it is.

Faster than light, at least through undistorted space, is a nonsense concept. As you can see from my comprehensive professional totally non-simplified diagram obtained through years of study and research, time moves slower as things move faster. At the spatial speed 0, time moves at its maximum speed. At the spatial speed c, time stops. Any speed faster than c just doesn't exist in the spacetime domain.

saw this earlier
y(y´(x)) = x solve for y

so i assume you would need to find y s.t. y´ = inverse of y. the only function i can really think of that has that property is y(x) = 0. how far off am i?

Serious question here. Is there a consensus about the fundamental principle of the universe? All particles need to be made out of something else in order to exist. Does science believe that this system is infinitely recursive? Is it even possible for a real fundamental particle to exist?

There's a really cool game that's free to download to show you just that

gamelab.mit.edu/games/a-slower-speed-of-light/

Wait hold up...

So based off that graph, we can go back in time?

Sure; you just have to go at a negative speed.

So they built a bike which eliminates the caster effect and the gyroscopic effect and it stayed upright, but have they done this in a vacuum?

How do I find the inverse laplace of the function F(s) shown in the picture?

1. L(𝛿(t-T))=e^(-Ts), i.e. e^(-Ts) is the Laplace transform a unit impulse (dirac delta) delayed by T.
2. The Laplace transform is linear, i.e. L(f+g)=L(f)+L(g) and L(k*f)=k*L(f).

So the inverse is just
f(t)=𝛿(t-1)+𝛿(t-2)+3*𝛿(t-3)+𝛿(t-6)

More generally, you normally try to express the function as a sum of terms each of which has a known inverse. If that fails, you can try the Fourier-Mellin integral.

how can people justify having glass platforms and glass stairs, especially in public places like in libraries and with elevations that could kill you if you fell from that height, isn't it dangerous as fuck, like what if a heavy person walks on it or if someone steps too hard on it or if it just breaks from general wear and tear and you fall through it, and it's not just about the safety aspect, isn't it really disrespectful toward people with a fear of heights

like look at how easily the skateboard made of glass breaks at 7:30

youtube.com/watch?v=KMwhGE0vd-w

or like if someone drops some pointy object on it or walks with stilettos on it

Dentist here.
You have a chance of developing something called pericoronitis that hurts a lot.
It is advised to remove the tooth before this in order to avoid pain and complications.
The procedure is simple.

ok they seem to have wooden stairs, but i could have sworn they used to have glass stairs

You wont be the only oldfag there i can tell you that much.
Eventually you will find people that are falling behind or old as you and life will pick up from there.
The important thing is to remember that nobody gives a shit about anyone.
Dont be nervous because nobody cares.

they actually did/do have glass stairs, this pic looks weird since it doesn't look transparent/translucent (maybe they painted it or something because it freaked people out) but it does say it's a glass stair and glass floor

age shouldn't be a problem at all

>read did/do as dildo

Was disappointed when I realized my mistake.

bbc.co.uk/news/technology-36494150
Stop being a pussssssyyyy.

> this one didn't break so none of it will break
anal kek

>Panicked tourists stampede across bridge as 3000ft-high glass walkway shatters beneath their feet

>But last September, tourists on a different walkway in China panicked when a panel smashed. A visitor had dropped a mug. The walkway had to be closed for repairs.

dude...

>isn't it really disrespectful
muh male/thin/non-acrophobia privileges
10/10 you made me slightly upset

thats actually a nice tresher for the fat people. the mighty glass will decide if you're thin enough to deserve to live or simply die in a terrifying fatass way :^)

you are a pure genius user, why didnt i think of this

a public place funded by taxpayer money like a library should be accessible to everyone (within reason), and glass stairs and platforms is a bit ridiculous, probably costs a lot for maintenance and repairs, you have to clean the glass and check for structural damage, and it's not even all that cool in the first place, they're just fucking stairs, they should just be there to walk on, not for architecture fetishists to fap to or for creeps to take upskirt photos through the glass

i dont think they take much more maintenance than normal, but dont quote me on that. thought i do agree with the last two points.
just to make it clear, i couldnt care what they made their stuff out of as long as its structurally sound, but glass would almost never be my first material of choice for that purpose, it has its places though

Could anybody give me general study tips and advice? Specifically, I need to study and refresh myself on a lot of material before starting grad school next month.

For Statistics, I'm not sure how to approach it since I'm awful at maths and I would imagine studying maths is entirely different than anything not-maths or physics (since no equations/problems, that sort of thing.)

Otherwise, for strictly information memorization, I was going to read a certain amount every day, try to pay attention to specific important information, make flash cards to help with memorizing and retaining key terms, and I'm not sure where to go beyond there.

My chemistry teacher was telling me some shit today but I wasn't paying attention and I don't enough to google it. All I can remember is that random molecules in something do some magnetic polar shit and it causes them to all line up or attract. THe signifact fact is that its random, but on a macroscopic scale its a reliable behaviour.

Sounds cool. Maybe your textbook will say something about it.

Don't have one. I'm English, we don't need pay $80 for the latest version that contains no new information. This is a stupid questions thread, so there's no point in being salty and passive aggressive about it.

is this what you're looking for?

google.com/#q=random molecules in something do some polar shit and it causes them to all line up or attract

>everything from capacitors to hyrdogen bonding, which I know about so why the fuck would she repeat herself

This is why you were bullied in school. Its some brownian motion shit.

the first result

chemistry.stackexchange.com/questions/1289/how-do-non-polar-substances-dissolve-in-non-polar-solvents

is this not it?

Yeah yeah, that's it, the electrons. Sorry man, obviously when I was googling first time I didn't type that.

kek it's all good have fun

Thanks. Have a Sunday Sport article.

>On the other hand, physics books (in my limited experience) tend to just throw around equations with lots of variables and integrals over various volumes with little explanation. I'm not saying I don't know what each symbol means, but it can get confusing to follow the logic along, and leaves me feeling a bit more shaky than with math.

sounds like the pretension version of "hold my hand these big equations are scary looking". don't kid yourself. the reason you have trouble with the equations with "lots of variables" is not because it isn't rigorous (it isn't), but because you don't understand the equations.

Are these talking about the same thing? Where does the value of the underlined term come from?

Thanks man

This will sound stupid, but worth asking.
What are the legalities and challenges in building private, unmanned, interplanetary research craft?
Such as a rover/robot that could act as a remote lab on say, venus or mars.

Hi, Elon.

Not elon, just a lurker.

transportation would be the main challenge. unless you're filthy rich or you get funded somehow it's not gonna happen any time soon

you can tell it's normal because of the way that it is

this bicycle research seems pretty dim-witted, hap-hazard and primitive
>en.wikipedia.org/wiki/Two-mass-skate_bicycle
>The existence of the TMS and the self-stability it exhibits suggests that the design envelope of rideable bikes is larger than previously thought.[7][8][9] For example, rear-wheel steering may not be as impossible as has been claimed.
>rear-wheel steering may not be as impossible as has been claimed
no shit sherlock!

Money.
Cheapest rocker costs 5 mil in one way and only gets you to the moon.

Rocket*

Anyone here know shit about vector fields