- Thread starter Sniper King 2020
- Start date
I stopped reading when you got to the calculus. Two years of that shit, plus a semester of differential equations, is enough for me.STDEV.S is the correct method. End of story.
The difference between the two (open google--cause statisticians don't use those terms, there is standard deviation (STDEV.P)--statisticians use sigma and then there is ESTIMATED standard deviation,(STDDEV.S) which is known a 's'.
Its like your measured values is "x" and the mean is "mu"
English variables mean "measured" and greek variables are "intrinsic"--properties of the distribution
Standard Deviation is the width on a Normal or Gaussian Distribution. The formula is:
View attachment 8323682
sigma is the Std Dev. mu (the u thingy) is the mean).
Its a complicated formula, but just know that sigma controls the width, and mu controls the location:
View attachment 8323683
That's pretty standard stuff, but that's pure THEORY (egads a running gag in my own posts). When you MEASURE something you are sampling from that theoretical distribution (you get points at random, from a random distribution). Assuming your distribution is normal (not always safe), you can estimate the TRUE Standard Deviation by using the Estimated Standard Deviation, s. They key here is there is some unknown TRUE sigma which we try and estimate by taking samples. The Estimated and True will only begin to approach equal once the number of samples becomes very very large.
So the TLDR version is STDEV.S would be the statistician's choice to ESTIMATE the standard deviation of your velocity.
Example: I ran created a distribution with mean 2800 and simga 10. I grabbed 5 samples at random, 10 times and took the STDEV.P--However, we KNOW its 10 (I made it!). Here are the results:
"True Method"
[13.275930373733024,
8.342655830573312,
7.23926247655942,
5.156843761443447,
8.550960467769086,
13.76093532000941,
3.2590625589140196,
7.783767404854264,
3.911747500033366,
7.031416934586289]
Estimated:
[14.842941390110614,
9.327372775023447,
8.09374150227517,
5.765526599966628,
9.560264439422538,
15.385193404759432,
3.6437427123280806,
8.702516519150631,
4.373466660444734,
7.861363121939068]
With the estimated std dev, you get a value that is higher (instead of dividing by num of samples, you divide by n-1 for math reasons--in reality using the "true" method induces a bias towards 0)--so you could get lucky or you could get unlucky.
OR
Based on the following random data I "sampled":
array([2794.70526224, 2816.48889134, 2797.31856425, 2785.55297754,
2791.62315356])
I would publish an s of 11.67 with 95% CI of (4.07, 14.80) meaning I am 95% sure the TRUE sigma lies on the interval 4.07 to 14.80
You use confidence intervals : since I have to publish shit for the dreaded peer review, I would say my estimated std dev is 10.4 (4.07, 14.80)
So I read that as a sample size of 5 means dick either way. But "s" is the correct method.
Also statisticians don't use excel, they use R, which is a filthy language.
I teach data science/AI so I use python:
Go to google colab and reproduce my results. I prob made a mistake, but I fuck it. That's how you think of this as a "statistician"
spaces are important in the code btw Due to RNG, your number may vary slightly from mine. I'm, not getting into psuedo-random numbers with howler monkies.
Google Colaboratory
colab.research.google.com
[FONT=courier new]import numpy as np p=[] s=[] n=10 size=5 for i in range( n ): x =np.random.normal(loc=2800, scale=10.0, size=size) p.append(np.std(x)) tmp = (x-x.mean())**2 tmp = tmp.sum() tmp = 1/(size-1) * tmp tmp = np.sqrt(tmp) s.append(tmp) import matplotlib.pyplot as plt plt.scatter(np.linspace(0,9,10),p,label="True") plt.scatter(np.linspace(0,9,10),s,label="Estimated") plt.legend() plt.show() sigma=[] for i in range(100): tmp = np.random.choice(x,5,replace=True) print(tmp) sigma.append(np.sqrt((((tmp-tmp.mean())**2).sum())/4)) print(np.percentile(sigma,95)) print(np.percentile(sigma,5)) print(np.sqrt((((x-x.mean())**2)/4).sum()))[/FONT]
By the vaxxed
When it comes to the maths that require more than fingers and toes I defer to someone else. I’ll sit up on a branch with the rest of my howler monkey brethren and do what we do best
Who the fuck are you, again?I forgot to mention that I am proud to live rent free in your mindsgood stuff kids. Keep it up!
Well I'm gonna miss him.
10/10
Would trash again.
and somedays I do just wanna sit and fling poo with the other monkeys
10/10
Would trash again.
and somedays I do just wanna sit and fling poo with the other monkeys
Beat me to it, damn it.
Or this
the best part is he thinks we need to be mad to make fun of him, bitch this is a sport.
Imma thinkin he doan know nuddin much. Jus hope ya’all ain’t clickin on his shit.
I forgot to mention that I am proud to live rent free in your minds
Dunno who that cat is. We were talking about that Brian Z feller. Now Brian, he craved attention. Wonder what happened to him?
Oh well. This is now a howler monkey thread anyways. Mo’ better
Oh yeah, it’s also a Spider-Man thread
You are not wrong. Not even a little bit.
Shit slinging, hoping to hurt that last feeling.
I 've had most of my feelings burned out and a few surgically removed. But, yes, the sport continues.
Some of this reminds me of working with my old friend, Lee. We would eat a nice lunch on Fridays (working construction) at a mom and pop diner where you could (around the turn of the century) eat yourself into a coma for about 8 dollars, including a nice tip from each of us.
We would go back to work and Lee would say, "I feel full and totally useless."
I would ask, "How do we tell the difference between now and before lunch?"
Can you feel the love in the room?
It’s funny how the idiot @Sniper King 2020 things we’re crying while we are having fun mocking his idiocy. An ego so large that he can’t tell laughing from crying? A bad case of cranial rectal inversion? Or just a plain idiot?
Stayed tuned for more exciting nothingness from the mock-king of idiots after these commercials.
Stayed tuned for more exciting nothingness from the mock-king of idiots after these commercials.
Y’all doing well! Major proud of you I am (Yoda grammar). Keep crying libs!
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Okay, I’ll give you the benefit of the doubt. Tell me your name so I can assess your stats competence. If you’re the real deal, email me your CV.
Thanks lib
Thanks triggered lib
Thanks triggered lib
LOL. Your credentials in mathematics are going to be assessed by a social scientist.
Triggered lib
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Honestly didn’t know that the forum was full of crying fragile leftist libs. Guess I shouldn’t have been so surprised
Just sad.
Learn how to post a meme.
1/10 on substance and skills.
Try harder.
R
Thanks for making my point you fagile lib. You remind me of a liberal “fact check” trying to invalidate anything that doesn’t comport with your narrative.
I think I’m good with concluding that this forum is full of leftists liberals. No wonder it’s full of mindless zombies. You’re renamed “Liberals Hide”
Thanks for making yourself an example of the cancel culture pushed by leftists. Now, get lost you liberal fake scum!
Lol.
Good luck on your bear pit experience.
Something tells me you'll flame out like the last few hundred dorks.
If only there was a way to turn up the heat...
R
Oh, okay liberal. Thanks for the encouragement to cancel myself. Spoken like a true lib
You hide liberals would love to simply cancel anything that doesn’t fit your narrative. Wow! Guess I shouldn’t be surprised by you liberals
This is probably one of the best implosions of someone who had a really good reputation.
The liberal “empty insult”. I’m surprised how many liberals are in the hide
I wouldn’t say you had a good rep but nice try lib
Build a thousand bridges but suck one dick, and nobody remembers anything about the bridges you built. All that statistical work down the drain because you opened your post by insulting the entirety of your target audience.
Meanwhile, you jump onto the 'Hide like:
Meanwhile, you jump onto the 'Hide like:
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