m********h
发帖数: 60 | 1 对于bivariate normal distribution,我们可以用 probbnrm.
但是想计算 probability of 3-dimension multivariate normal distribution，不知
道SAS里面有没有function可以用的？或者有什么办法可以计算的用SAS。
多谢！ |
|
B******5
发帖数: 4676 | 2 我怎么觉得(x1,x2,x3)还是joint normal呢？
)都 |
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D*****a
发帖数: 2847 | 3 so what.
a degenerate normal density..
x3 |
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s******u
发帖数: 21 | 4 谢谢tamuer兄：）
如果说covariance matrix of (x1,x2,x3) is definite positive, 那结论一定成立吗？
如果(x1,x2),(x1,x3), (x2,x3) 都是一样的normal distribution,结论又成立吗？
不知道有没有相关的参考书？ |
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t****r
发帖数: 702 | 5 如果X1,X2,X3是独立的Normal分布的话，他们的联合分布也是
联合正态的,至少你的推论在这种特殊情况下是对的。不过要证明你的猜想的话，恐怕还
不是一个trival的问题。
吗？ |
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p****l
发帖数: 23 | 6 x and y are i.i.d normal, left-truncated at 0, with mean \mu and variance \
sigma. Is x+y normally distributed with mean 2\mu, variance 2\sigma and left
-truncated at 0?
thanks. |
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w********u
发帖数: 328 | 7 the sample size is extremely small but the population is very large, for
example, the frequency of some cancer is extremely low.so it doesn't make
sense to say that the sample follows normal dist.
my question is
1 at least how many sample roughly i need to conduct a power analysis or
what's the lowest frequency to conduct a power analysis
2 the proc power in SAS is for normal dist.power analysis, so which method
could be used in this case, SAS preferred.
Thank you! |
|
w********u
发帖数: 328 | 8 I want to calculate the POWER.
SAS code:
proc power;
onesamplemeans
mean = 8
ntotal = 150
stddev = 40
power = .;
run;
This method makes sense when it follows normal dist., but my case is that
the sample size is extremely small but the population is very large, i can't
say that it follows normal dist., i assume it doesn't follow any particular
dist. but i haven't got the data yet, i wonder which method could be used
in this case and what's the sample size needed to conduct any analysis. for
examp |
|
j******1
发帖数: 62 | 9 I am trying to predict the freshmen graduate rate. I applied the
discrimimant analysis, denpendent variable is degree (graduate or not),
independent variable is hsgpa (high school gpa).
hsgpa is not normally distributed. Please see the attachment for QQplot of
hsgpa.
I applied the box-cox transformation to hsgpa to make it normal and below
is the result.
Transform | L [95% Conf. Interval] Skewness |
|
j******1
发帖数: 62 | 10 Thanks a lot for your reply.
But Test of Homogeneity of Within Covariance Matrices shows that with-in
covariance matrices will be used in the discriminant function. That means I
need to use quadratic discriminant functions. Qudratic rule is sentitive to
departures from normality. So it would be good to transform hsgpa to nearly
normal. |
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F****r
发帖数: 151 | 11 Usually, it is assume for normality so that valid inference can be drawn
upon parameters; when there is outlier, some inference may be invalid based
on the normal assumption... |
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f**********t
发帖数: 1001 | 12 嗯，感谢大家的回复们。
个人感觉只看到过error的Normal distribution assumption，没看到过数据的Normal
distribution assumption。呵呵 |
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c*******n
发帖数: 300 | 13 y|X是normal. linear regression并不要求error follow normal distribution.但是
，常见的估计方法却需要这个假设。 |
|
D*********2
发帖数: 535 | 14
nope，是Y normal。
如果X是fixed variable, Y|X没意义。
如果X是random variable，其实在simple linear regression的数理推理中需要的是（
Y,X） bivariate normal. |
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d******e
发帖数: 7844 | 15 应该把你打回去重学。
如果是random design, linear regression的要求是，E(Y|X)是linear function of X
和Var(Y|X)是normal。更一般的要求是monoment condition, Var(Y|X) = 0和Var(Y|X)
joint normal只是一个特例罢了 |
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b*****n
发帖数: 685 | 16 Y也是normal的没错，只不过此normal的mean是X的function而已。 |
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p******r
发帖数: 1279 | 17 y=a0+ a1*X1 + a2*X2
y是continuous变量
做完regression发现 residual的normality assumption test fail了。
除了对变量做transform，还能干什么呢？
如果transform了后，normality assumption test还是fail呢？ 还有其他招儿吗？谢
谢！！ |
|
z**********i
发帖数: 12276 | 18 这个是OUTCOME,BMI, BODY MASS INDEX, 有个文章说它不是NORMAL,但取了倒数,就
NORMAL了.所以,我取了倒数.
接下来,想用PROC MIXED,想看看它和其他VARIABLE的关系,比如,DIETRAY, PHYSICAL ACTIVITY,以及一些地域的VARIABLE,国家...建个MODEL.
多谢答复! |
|
A*******s
发帖数: 3942 | 19 Y是不是normal的没关系，conditional normal就行
fit了之后，看看residual
ACTIVITY,以及一些地域的VARIABLE,国家...建个MODEL. |
|
e*****t
发帖数: 642 | 20 你是在说QTL吗？
normalization是在比较不同background的数据时用的。你为什么要normalization，没
看明白。那些local trends也许可以看作noise。
至于用什么test pvalue，取决你的y是什么，比如是case control，可以用chi-square
test，如果是什么continous variable，可以用likelihood ratio test。 |
|
o******e
发帖数: 1001 | 21 假定(X,Y)和(Y,Z)分别为bivariate normal distribution, 我们可以证明(X,Z)也是
bivarate normal distribution.
证明过程如下：令u,s,v,t为独立标准正态分布。
从 (X,Y) 为bivarate,我们有：
Y=a_y*u (我们省略均值)
X=a_x*u+b_x*s
从 (Y,Z) 为bivarate,我们有：
Y=c_y*v
Z=d_z*v+e_z*t
因为Y为同一变量，我们有u=v,因此，
X=a_x*u+b_x*s
Z=d_z*u+e_z*t
(X,Z)^T=(a_x,b_x,0;d_z,0,e_z)*(u;s;t)
(X,Z)是独立标准正态分布的线形转化，所以为bivarate.
但是奇怪的是，我从来没有在书上或paper上看到讨论bivarate 的transitivity,我的
证明有错吗？谢谢！ |
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d******e
发帖数: 7844 | 22 Covariance Matrix Rank deficient.
举个简单的例子，x服从N(0,1), y = x，那么(x,y)服从正态分布。但是这个协方差矩
阵rank只有1。无法求逆，自然也无法算density。其实Rank deficient的情况很多，常
用的PCA的假设就是covariance是low rank的。
正态分布的定义是
A random vector is said to be multivariate normally distributed if every
linear combination of its components has a univariate normal distribution.
并不是由density function来定义的。 |
|
f*********8
发帖数: 165 | 23 sample1 sample2 sample3....sample100
var1
var2
var3
.
.
.
var1000
我想quantile normalize 这100个sample,得到一个reference distribution。 以后有
新的sample，就用这个reference distribution做quantile normalization。
请问版上牛人，这个reference distribution怎末整出来，能给个R code 的例子吗？
多谢。 |
|
g**********t
发帖数: 475 | 24 You mean the residual is not normally distributed? You may try to transform
your response variable to make the residual fit normal distribution better. |
|
y*****u
发帖数: 224 | 25 It is well known that w test can be used for normality test of a set of data
without pri knowledge of the norm distribution of the data.
My question is if the norm distribution parameter (mean, var) is known,
given a set of data, how to test the normality. Any clue? |
|
l**********8
发帖数: 305 | 26 Linear reggresson is fairly robust for validity against non-normality, but
it may not be most powerful test available for a given non-normal
distribution.....
确？ |
|
h***i
发帖数: 3844 | 27
sigma2)
-----这句错了
由此可以推得y也必须iid服从正态分布N(X*beta, sigma2)。
-----即使上句对了，这句也错了
X*
在不知道每一个y对应的mean的前提下，对y做Normality检验的结果是没有意义的。
换句话说，假设Linear Regression的model成立，y服从正态分布N(X*beta, sigma2)。
-----这句错了,同第一句
但如果X*beta本身的skewness很大，可以想象y的skewness也会很大，
------这句不知所云，难道你在讨论X的分布？
此时对y做Normality检验，检验结果显然是false的。
-----这句错了, 你没想如果x是常数会怎么样么？ |
|
c********d
发帖数: 253 | 28 Gauss-Markov theorem already indicates that no normality assumption is
required. But if the errors follow normal distribution, you can prove that
the OLS estimator is the same as MLE, thus it can share the efficiency
gained by MLE. |
|
c********d
发帖数: 253 | 29 Gauss-Markov theorem already indicates that no normality assumption is
required. But if the errors follow normal distribution, you can prove that
the OLS estimator is the same as MLE, thus it can share the efficiency
gained by MLE. |
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w*****n
发帖数: 375 | 30 也说一下为什么需要normalization, 对什么normalization |
|
w*******y
发帖数: 60932 | 31 Logitech has their Logitech QuickCam Communicate Deluxe Dented Box special
for $24.99 normally $79.99.
Logitech QuickCam Communicate Deluxe - Dented Box $24.99 normally $79.99
Technical Specifications
1.3-megapixel sensor with RightLight2 Technology
Built-in microphone with RightSound Technology
Video capture: Up to 1280 x 1024 pixels (HD quality) (HD Video 960 x 720
pixels)
Frame rate: Up to 30 frames per second
Still image capture: 5 megapixels (with software enhancement)
USB 2.0 certified
Opt |
|
|
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w*******y
发帖数: 60932 | 34 There are a handful of Authentic NFL jersey's on sale at Eastbay for $49.99.
I am not sure if this is a price mistake, but these are the jersey's that
typically sell for more than $250. They don't have my team but the deal is
for active players.
Cowboys | Tony Romo | Blue
Buccaneers | Josh Freeman | Red
Panthers | Steve Smith | Black
Patriots | Tom Brady | Navy
Falcons | Matt Ryan | Black
Bills | Cj Spiller | Navy
Texans | Andre Johnson | Navy
Rams | Steven Jackson | Navy
Chiefs | Matt Cassel... 阅读全帖 |
|
w*******y
发帖数: 60932 | 35 Just got an e-mail for Free Darcus Tori Simulated Ruby or Amethyst Heart
Shaped Earrings! Just in time for Valentine's Day!
Retailed at $59.99 each, yours free + shipping after code(s).
Ruby earrings free after code 0704: Link:
http://darcustori.com/StoreFrontProfiles/DeluxeSFItemDetail.asp
#.TysWa4EbEpA" rel="nofollow" target="_blank" onclick="_gaq.push(['_
trackEvent', 'thread', 'click', '3898120 - free-darcus-tori-ruby-or-amethyst
-heart-shaped-earrings-shipping-normally-59.99-each']);">http:... 阅读全帖 |
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m*******r
发帖数: 4 | 36 have a feeling that i could use quaternions for better normal interpolation,
but how do i do that? since normals are just vectors, but quaternions
are rotation representation ...
thanks a lot |
|
b********n
发帖数: 38600 | 37 Robin Williams death: The difference between depression and normal sadness
http://www.foxnews.com/health/2014/08/12/robin-williams-death-d
Here are some facts about depression:
•Although major depression can strike people of any age, the median
age at onset is 32.5, according to Washington University School of Medicine
in St. Louis.
•Depression is more common in women than in men, according to
Washington University.
•Men with depression are more likely than depressed women to a... 阅读全帖 |
|
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s******n
发帖数: 518 | 39 sometimes, when you want to play a video in youtube, you may have to go
through a commercial. In general , you can click on "You can skip this in 5s
" or just finish it. But sometimes, this idiot youtube would play that
commercial sound into the normal video. So the sounds of two videos are
mixed together. |
|
|
发帖数: 1 | 41 英文混的一般叫normal? 太Chinglish, 为什么这么在电视上乱说? |
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d**********i
发帖数: 524 | 42 搞笑节目而已。又不是英语教学
：英文混的一般叫normal? 太Chinglish, 为什么这么在电视上乱说? |
|
|
发帖数: 1 | 44 把普通说成 normal，说明你们中国人死读书
善于刷题，但很多时候狗屁不通 |
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w*********r
发帖数: 42116 | 45 普通和normal基本不沾边儿，大陆人英语水准不会那么低吧。 |
|
M****u
发帖数: 17708 | 46 应该是average
：
：把普通说成 normal，说明你们中国人死读书 |
|
A***e
发帖数: 130 | 47 http://nautil.us/blog/the-present-phase-of-stagnation-in-the-foundations-of-physics-is-not-normal
Nothing is moving in the foundations of physics. One experiment after the
other is returning null results: No new particles, no new dimensions, no new
symmetries. Sure, there are some anomalies in the data here and there, and
maybe one of them will turn out to be real news. But experimentalists are
just poking in the dark. They have no clue where new physics may be to find.
And their colleagues in t... 阅读全帖 |
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M*****s
发帖数: 3436 | 48 【 以下文字转载自 NBA 讨论区 】
发信人: Mitobbs (静如处子), 信区: NBA
标 题: 昨天听完了杨安泽近7个小时的 The War on Normal People
发信站: BBS 未名空间站 (Mon Aug 19 08:22:41 2019, 美东)
杨安泽和他的别的视频之后心灵受到了很大的震撼，当时就给他捐款$50。杨安泽对亚
裔形象的提升是空前的怎么说都不过分。曾几何牙医有机会在主流媒体发声，而且获得
了左右两派的喝彩。他的影响是长远的革命性的，将影响人类几亿人的命运......
https://www.youtube.com/watch?v=MC25cPvp4zg
知乎上文章
杨安泽出生在 Schenectady NY, 在NH的Phillips Exeter Academy读中学，本科在布朗
大学读政治经济学，在哥伦比亚大学法学院获得法律博士学位。1999年毕业后杨安泽在
一家知名法律公司当了5个月律师。无法忍受无聊的工作，杨安泽开始了互联网创业。
经过数年商海沉浮，2006年杨安泽成为一家做教育培训的创业公司（ https://www.
manh... 阅读全帖 |
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m******8
发帖数: 2153 | 49 http://www.religiondispatches.org/dispatches/candacechellew-hod
According to new census figures, the number of people reporting that they
are living with a same-sex partner has risen 52 percent in the last decade.
That’s almost 902,000 people who are living all across the United States.
Even here in my own incredibly conservative state of South Carolina, the
number of same-sex couples increased and a quarter of them are raising
children.
It’s those kinds of facts that have right-wing media like ... 阅读全帖 |
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R****y
发帖数: 456 | 50 大牌林立，期待许久的电视电影《The Normal Heart》终于在HBO周日的晚间档上映了。
即使没有看过那部闻名遐迩的同名舞台剧（Tony award winning play），但依旧由于
过高的期望值导致我对虎头蛇尾的终剧不免有小小的失望。映像里只记得各种用力过度
的Mark Ruffalo和孔雀（Matt Bomer）开屏后转瞬凋零的视觉冲击。
与20年前那部同志AIDS题材的《Philadelphia》的主题类似，同样是反映80年代特殊社
会大背景下LGBT边缘群体与主流世俗社会的抗争实录。例如前晚剧中人用最高频率呐喊
着的“Fighting”就是那个时代的主旋律。只是两部电影，围绕着同样的主题，却展现
出截然不同的表现形式。在我眼里，前者的斗争事实上是与主流社会寻求和解的过程，
而后者显然是激烈冒进永不会停歇在战斗。好似Mark Ruffalo饰演的Ned，与政府、社
团、朋友、亲人、爱人，甚至与自己，永不停歇的在争斗……惟有躺在孔雀怀中，那安
宁短暂的一瞬间。
好想对他说，请你停下来歇一歇，别太执着较真，在脆弱的生命面前，一切都不过都是
浮云。 |
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