t*f
发帖数: 7 | 1 no problem. get a large invetor made for rvs, and use lcd monitors rather
than crt monitors. |
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n***s
发帖数: 1257 | 2 Let X be a Random Variable and f be a Borel measuable function from R1 to R1
. What's the condition for X and f(X) to be independent?
Thanks |
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n**p
发帖数: 35 | 5 我现在在RVS读一些美国文学、艺术之类的课。其它课都修完了。我朋友说她是2年前的
价格300多，在ACC读的。真够便宜的，估计现在没有这个价格了。 |
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z*******9
发帖数: 167 | 6 下面是一道金融版里的题目和解答，挺有意思的，不过那个答案有严重的
逻辑错误。金融版上好像没人指出来，看来他们的数学学得的确不怎么样。
看看物理版的童鞋们如何。
请找出解答中的error(s).
Two RVs, X1 and X2, and you need to decide which one is larger. Apparently,
if you don't know X1 and X2's
values, then you have probability 0.5 to be correct by randomly guessing,
and you cannot do anything
better than that.
Now, if you are told the X1's value, say X1 = a, do you have a better
strategy to win with probability better
than 0.5?
At first it sounds unlikely, but as pointed out by others |
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f*********1
发帖数: 117 | 7 谢谢findle!
你的意思是the average of a sequence of iid RVs?
a sequence of iid random variable |
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j****e
发帖数: 140 | 8 what is the simplest way to generate 2 uniform random vaiables of given
correlation? |
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h*****r
发帖数: 1052 | 10 thanks, but what I mean is the tail distribution, it seems there are many
definitions about tail distritubion outside.like right tail distribution,
heavy-detail distribution, or long-tailed distribution
http://en.wikipedia.org/wiki/Heavy-tailed_distribution
I am wondering which one is easier for binomial RVs to have a close form. |
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l******y
发帖数: 507 | 11 3 RVs have same pairwise correlation rho, what could rho be? |
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s***e
发帖数: 267 | 12 Generalization to n RVs, the range of rho will be
rho >= - 1/(n-1) |
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s***e
发帖数: 267 | 13 画图对于3个RV相对容易理解，对于多个可能不是那么直观了。我的理解是：
sample correlation converge to rho, so just consider sample correlations of
3 RVs. When each sample vector of
norm 1, then sample correlation is essentially the cosine of their angle.
The maximum angle you can get for 3 points on a unit sphere is 120 degree,
so you just compute the range
of cosine(alpha), alpha from 0 - 120 degrees.
The algebraic way of computing the determinant is in fact quite easy, if you
find out the right way. The
general formula for n RV |
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s***e
发帖数: 267 | 14 这个以前大家讨论过，题目叙述很简单，但是觉得非常有意思。
Two RVs, X1 and X2, and you need to decide which one is larger. Apparently,
if you don't know X1 and X2's
values, then you have probability 0.5 to be correct by randomly guessing,
and you cannot do anything
better than that.
Now, if you are told the X1's value, say X1 = a, do you have a better
strategy to win with probability better
than 0.5?
At first it sounds unlikely, but as pointed out by others already, it is
possible to win by the following
approach:
====
Gener |
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A*****s
发帖数: 13748 | 15 证明的过程中用到了P(S_n <= 1-X_n+1) = (1-X_n+1)^n/n!
如果有了这个结论这道题都不用证了啊，直接把X_n+1=0，结论就出来了
这不是用一个更general的结论来证一个narrow的特例么？ |
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k*******d
发帖数: 1340 | 17 you are right. we should prove the more general result:p(Sn \leq 1-t ) = (1-
t)^n / n! using the same idea |
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A*****s
发帖数: 13748 | 18 归纳法从n推倒n+1的时候，用了比论题更general的结论 |
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A*****s
发帖数: 13748 | 19 怎么用the same idea证more general result?
1- |
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k*******d
发帖数: 1340 | 20 用数学归纳法，用积分求概率，方法和书上一样，我以前推过，可以推得出来 |
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z***e
发帖数: 5600 | 21
what does the LHS mean?
N(x) where N is the standard normal distribution? Then no such c
exists because if x-> -infinity, LHS=1 and RHS=0
Again, what do x(1),..,x(n) mean? The joint density function of
n independant RVs X1...Xn is, by definition,
g(x1,x2,..,xn)=f1(x1)...fn(xn)
where fi are the density of xi. In your case all fi=f, there should be
no n! factors here.
-Z. |
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p********a
发帖数: 5352 | 22 ☆─────────────────────────────────────☆
jejune (孑孓) 于 (Wed Nov 7 12:47:17 2007) 提到:
what is the simplest way to generate 2 uniform random vaiables of given
correlation?
☆─────────────────────────────────────☆
sir ( 郎 ) 于 (Wed Nov 7 18:22:27 2007) 提到:
it is hard to get the simplest one
a simple one is generate independent x and y
and use x, x+ay, where a is a parameter to adjust
☆─────────────────────────────────────☆
jejune (孑孓) 于 (Thu Nov 8 09:49:55 2007) 提到:
but if x,y ~ uni |
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x***x
发帖数: 3401 | 23 I dont think variance of the ratio of two RVs has simple formula as that,
unless your X and Y has some special distribution - I might be wrong.
The usual way to go is to use delta method to approximate.
I dont quite understand 1). what is that about? |
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D******n
发帖数: 2836 | 24 MUTUAL INFORMATION for discete RVs |
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K******S
发帖数: 10109 | 26 there's a company making RVs on top of Unimog. It was featured on Travel
channel. :) you can probably camp anywhere. |
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r********e
发帖数: 33 | 30 Just FYI –
Here is the link to sign up Groupon with any of your email adresses
http://www.groupon.com/r/uu26487619
After signup, you could purchase $7 for $15 Ebay gift card offered
from Groupon –
http://tinyurl.com/4zw4zpn
or
http://www.groupon.com/deals/ebay?
utm_medium=afl&utm_campaign=361116&utm_source=rvs
I paid $7 and bought a $15 Ebay gift card yesterday (they sent a gift
card electronically to me later). I have already used it for buying
accessories for my computer :--) It works fine fo... 阅读全帖 |
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w*******y
发帖数: 60932 | 32 Link:
http://www.graveyardmall.com/sylvani-motion-activated-led-guide
It looks like these are selling for $40 on Amazon...
Product Description
Gone are the days of fumbling for a light switch in the dark. The Sylvania
LED Stair & Hallway Lighting Kit has a motion sensor that automatically
turns LED lights on when movement is detected. An adjustable 'on-time' can
be set to automatically shut-off 20, 40 or 60 seconds after motion is no
longer sensed.
The built-in photocell makes LEDs active only i... 阅读全帖 |
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w*******y
发帖数: 60932 | 33 Schumacher XM1-5 1.5 Amp Fully Automatic Power Charger and Maintainer:
http://www.amazon.com/Schumacher-XM1-5-Automatic-Charger-Mainta
quote
Product Features
Great for maintaining small and large batteries kept in storage such as
motorcycles, classic cars, RVs, boats and more
Unique automatic battery charger maintains both 6 and 12 volt batteries
keeping them at full charge using float-mode monitoring
LEDs indicate Connected, Charging and Charged
Reverse-h... 阅读全帖 |
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g*******n
发帖数: 12458 | 34 刚刚打这个电话来着,说已经disconnected.
竟然还看见了这个规定,呵呵.看来沙滩上也不能玩排球什么的嘛.
BEACH RULES - Ball-throwing, frisbees, and other sports are not allowed
while the Beach Patrol Guards are on duty between 9:00 a.m. and 5:30 p.m.
daily from May 30 to September 15.
RV PARKING is available at the Kitchen Restaurant on Wicomico Street for a
fee. RVs and oversized vehicles (6'8" wide or wider, and/or 21'2" long or
longer), may not be parked on municipal streets or parking lots from June 1
until September 15. However, limite |
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