z**********i
发帖数: 88 | 1 I will appreciate any input you may give.
I am runing glm procedure, but I get one more test significant in contrast
than in pairwise multiple comparison. I don't know why. Below is the code
and output.
proc glm data=out.final;
class dx;
format dx dx4x.;
model &v =dx;
lsmeans dx;
means dx/tukey;
contrast "demented vs normal" dx 1 0 -1;
contrast "demented vs mci" dx 1 -1 0;
contrast "mci vs normal" dx 0 1 -1;
run;
1. Least Squares Means;
Least Squares Means
Q1_PARTAPP
dx ... 阅读全帖 |
|
x******a
发帖数: 6336 | 2 A question regarding using PCA to capture the pairwise covariance matrix.
Suppose I have 10 times series and 250 data point for each time series in
the format of a matrix. Let's call it A of shape 10*250,Let us call the
covariance matrix COV and it is a 10*10 nonnegative defined matrix.
I would like to capture this matrix COV with a one-factor model,
0.Is PCA the right direction on this?
1.Assuming 0. is right. We find the largest eigenvalue lamdbda_M and the
correponding vectors v_M of COV. The... 阅读全帖 |
|
m*****f
发帖数: 1243 | 3 常常见到的是给定sum, 找array中的pair, 现在变化一下
Given a list of numbers, A = {a0, a1, ..., an-1}, its pairwise sums P are
defined to be all numbers of the form ai + aj for 0 <= i < j < n. For
example, if
A = {1,2,3,4},
then
P = {1+2, 1+3, 1+4, 2+3, 2+4, 3+4} = {3, 4, 5, 5, 6, 7}.
Now give you P, design an algorithm to find all possible A. |
|
s*******y
发帖数: 558 | 4 Given n points and an integer k, how to find k point out of these n
points, such that the sum of the pairwise distances of these k points
are the maximal?
I guess this is an NP-hard problem. Are there any approximation algorithms
in the literature with error analysis?
thanks |
|
l*****k
发帖数: 587 | 5 new to sas...
I have a category variable that have 10 levels, a numerical
variable evalue.
Is there an easy way to generate pairwise ttest among the 10
levels of category using evalue?
Thanks |
|
m**********r
发帖数: 122 | 6 请问pairwise t-test 和 paired t-test是一回事吗？ |
|
x******m
发帖数: 736 | 7 一组数据9个group，比较每两个group的difference，
我先用t test，然后用p.adjust for multiple testing。
另外一种方法用pairwise.t.test.
这两种方法理论上是一样的，为啥结果会差很多？ |
|
g**********t
发帖数: 475 | 8 multiple sequence alignment也是可以用来算pairwise distance的。multiple
sequence alignment理论上应该比pairwise alignment准确。multiple sequence
alignment一般的策略是先进行pairwise alignment，然后再把结果“合并”起来。为
什么要把序列掐头去尾？末端序列测的不准？“接下来A和C就没法接着对比了”是虾米
意思？程序报错了？
sequence
A |
|
C******o
发帖数: 116 | 9 求助牛人，帮我看看这个题目是要干嘛的？题目都看不懂，谢谢了
2，An election is held using the method of pairwise comparisons. Suppose
that X is the winner of the election under the method of pairwise
comparisons, but due to an election irregularity, there is a reelection. In
the reelection, the only changes are changes that favor X and only X (
specifically, you can interpret this to mean that the only changes involve
voters who move X up in their ballot without altering the relative order of
any of the other candidates). Expl... 阅读全帖 |
|
D**u
发帖数: 204 | 10 The R^3 analogue of Hopf fi bration is indeed surprising.
Here is my thoughts on the new question "how to partition R^3 into pairwise
non-parallel lines?".
We know that the hyperboloid of one sheet
(x^2/a^2 + y^2/b^2 - z^2/c^2 = 1)
can be partitioned with pairwise non-parallel lines.
If we partition R^3 into hyperboliods
x^2/a^2 + y^2/a^2 - z^2 = 1 (0
PLUS the z-axis,
and then partition each hyperboliod with line, then these lines should be
pairwise non-parallel. |
|
s*******z
发帖数: 83 | 11 之前在这个版上看到的问题, 百思不得其解:
有一个0/1的矩阵, 找到里面的两行使得它们有最多的位置相同的0/1
比如: 00010与00100 有三个相同的. 当时同学说面试的阿三不允许pairwise的比较.
类似的题目还有：
给一个sentences的list, 找其中两个句子, 它们有最多的common words.
这类的题目觉得总避免不了pairwise的比较, 不知道有什么更好的方法 |
|
wh
发帖数: 141625 | 12 问问门德尔松算浪漫还是古典呀？还是中间过渡的？我其实吃不准我感觉最通俗的是不
是仲夏夜之梦的片段，里面还用了他的string symphony no. 5 in b-flat major，用
了其中的andante和presto两段；还用了song without words op. 109 for piano and
cello. 说不定我觉得通俗的是后面这几个作品。记不清是哪个了。他十七岁就能创作
经典作品，莫扎特年纪更小；画画、写作都没有那么小而有成熟作品的，音乐创作不那
么需要经验积累、更讲天赋天才吗？他们去世都好早啊，就像英国那几个浪漫主义诗人
，一个比一个死得年轻。浪漫主义就是命不长。
还有我发现，音乐评论真难看懂啊。我把音乐系学生写的介绍抄在这里，看得我似懂非
懂，术语很多。文学评论好像没那么难看懂。艺术（音乐、画画、舞蹈等）评论可能都
比文学评论更专业、更难懂：
……He originally composed the Overture as a piano duet before orchestrating
it in 1827. After a brief sequ... 阅读全帖 |
|
wh
发帖数: 141625 | 13 另外再问问：门德尔松算古典到浪漫的过渡人吗？我其实吃不准我感觉最通俗的是不
是仲夏夜之梦的片段，里面还用了他的string symphony no. 5 in b-flat major，用
了其中的andante和presto两段；还用了song without words op. 109 for piano and
cello. 说不定我觉得通俗的是后面这几个作品。记不清是哪个了。他十七岁就能创作
经典作品，莫扎特年纪更小；画画、写作都没有那么小而有成熟作品的，音乐创作不那
么需要经验积累、更讲天赋天才吗？他们去世都好早啊，就像英国那几个浪漫主义诗人
，一个比一个死得年轻。浪漫主义就是命不长。
还有我发现，音乐评论真难看懂啊。我把音乐系学生写的介绍抄在这里，看得我似懂非
懂，术语很多。文学评论好像没那么难看懂。艺术（音乐、画画、舞蹈等）评论可能都
比文学评论更专业、更难懂：
……He originally composed the Overture as a piano duet before orchestrating
it in 1827. After a brief seque... 阅读全帖 |
|
M***7
发帖数: 2420 | 14 Hi there,
The table is like
ID1 ID2 similarity
1 2 95%
1 3 80%
...
1 10000 60%
2 3 70%
...
Suppose there are 10000 distinct IDs, and the table stores all pairwise
similarities. Now I want to retrieve a subset of IDs and make sure that the
pairwise similairity between every two IDs in the subset is in a specific
range (e.g. 70~85%).
Anyone help me out. Thanks. |
|
M***7
发帖数: 2420 | 15 I want a subset of IDs, like
-------------------------
ID
1
3
4
.....
------------------------
that having all pairwise similarities between 70~85%.
The way you suggested is not working since it eliminates certain possible
pairwise comparison between IDs in the subset.
70 |
|
M***7
发帖数: 2420 | 16 First, the original table contains all possible pairwise similarities.
It is possible to get more than 1 subset. So I would want to get a whole subset, for example, 2000 out of
10000 while all possible pairwise similarities in the 2000 IDs are in the range, then use some other constraints to trim it down.
Thanks |
|
D**g
发帖数: 739 | 17 第一，你得确认试验数据符合正态分布，如果每组样本量很小，或者有文献说response
value不是正态的，应该用non-parametric方法或者把原始数据做transformation.最
常见的是取对数，然后用ANOVA.不然，应该用ANOVA的non-parametric version:
Kruskal Wallis test
第二，ANOVA或者K-W test 如果p-value > 0.05, POST HOC pairwise test 就可以免
了。因为前面一个p>0.05的意思就是：考虑进multiple comparison的因素并调整TYPE
I 错误（没有区别却错误地认为有区别的概率）以后，没有任何一对比较会是显著的。
有很多方法调整multiple comparison，但前面的p保证了无论你用什么方法，没有一种
会给你一个显著的比较结果。
第三，如果p-value <0.05, 就值得做pairwise的比较。最简单的是用0.05/所有可能的
比较总数作为显著性CUT OFF值。如果你前面用的K-W test, 这里应该用Wilcoxon-Mann
- |
|
|
m**z
发帖数: 787 | 19 pairwise coupling? if you use free energy for your activity, then the
pairwise coupling free energy = AB-(A+B). In your case, the number will be
97.
If your number refers to a binding constant, for instance, then the coupling
free energy=-RTln(AB/(A+B))=-RTln(100/3)
This is what I used in these cases. But don't know whether that fits your
case...
3. |
|
s*****0
发帖数: 357 | 20 Step 1: one-way ANOVA
| |-->如果不显著，STOP.
|
|-->如果显著,说明至少有两组间存在显著性差异，GOTO Step 2。
Step 2: Multiple comparison, 必须控制overall significance level (假设0.05）
。很多选择，比如Bonferroni，Scheffé, Tukey等等。各自都有各自的适用情况和优
缺点，懒得费笔墨，自己翻翻书或者网上搜搜吧，比如Bonferroni在comparison增多的
情况下会太严苛，Tukey最适合pairwise comparison(在你的例子中即4选2,会有6个对
照).
Step 2会得到你想要的答案，既那些组存在显著性差异。
设每组100只老鼠。然后所有检测值都满足equal variance和normal distribution。
（2
。这种设计应该用one-way ANOVA pairwise comparison吧？有些文章用的是t test。
2vs1, 3vs1, 4vs1,然后 |
|
j*********j
发帖数: 124 | 21 Please check the following list:
http://en.wikipedia.org/wiki/List_of_sequence_alignment_softwar
but I think what you want is not MSA tool, but pairwise alignment tool (I
think you want to align all query sequences to one reference sequence and
order them according to the sequence identity?). So you may want to use one
in the pairwise alignment section in the list. |
|
s******h
发帖数: 539 | 22 I'll give you an example that says x, y, z are marginally normal and
pairwise independent but jointly can have infinitely many possible
situations.
Consider (X, Y, Z) with the following density function (don't mess those '{'
,'}'):
f(x, y, z;theta)
= 1/sqrt{2*pi}^3*exp{-(x^2 + y^2 + z^2)/2}*
{1 + theta*xyz*exp{(x^2 + y^2 + z^2)/2}*I{-1<= x, y, z <= 1}},
theta can be any real number such that theta < exp{-3/2}.
In this case, f(x,y), f(x, z), f(y,z) are all normal densities with x, y, z
pairwise i |
|
x**g
发帖数: 807 | 23 你可以在Excel里把小点.转化成999，然后再SPSS在Variable View里将999 标示成缺失。
missing values中三个选项： exclude cases listwise/
exclude cases pairwise/
report values
都不是最好的处理缺失数字的办法，会导致不同程度的误差。根据你的数据分析模型，
你可以采用multiple imputation 或者Maximum Likelihood处理缺失数据。
listwise
pairwise |
|
c****y
发帖数: 94 | 24 It sounds like that you did a pairwise comparisons among those methods. You
need to apply adjustment. You actually should have 10 pvalue (5x4/2). If you
want to use Bonferroni Correction, it may be too conservative.In sas, you
can use proc multtest with hommel option (different way to control family
error rate). Hope it can work for you. If adjusted p-value is not
significant, it just means there are not significant difference between the
methods (2 methods compared). Actually, you should do ANO... 阅读全帖 |
|
A**H
发帖数: 4797 | 25 谢谢
我根据这里的方法做的clustering
http://www.statmethods.net/advstats/cluster.html
用的其中的Partitioning这一节，我得到了一个"Within groups sum of squares"
versus "Number of Clusters" plot. 从这个plot里面我选了clusters = 5，然后做下面
fit <- kmeans(mydata, 5) # 5 cluster solution
# get cluster means
aggregate(mydata,by=list(fit$cluster),FUN=mean)
# append cluster assignment
mydata <- data.frame(mydata, fit$cluster)
我得到了哪个项目应该归到哪一类里面
感觉到这里，似乎就已经做完了。。。。。我知道了哪些项目应该编排到一起
然后，我再根据下面这个
http://www.stat.columbia.edu/~martin/W2024/R3.pdf
做anov... 阅读全帖 |
|
f**d
发帖数: 768 | 26 这是一本计算神经科学的优秀著作，全文拷贝这里（图和公式缺），有兴趣的同学可以
阅读
如需要，我可以分享PDF文件（－－仅供个人学习，无商业用途）
From Computer to Brain
William W. Lytton
From Computer to Brain
Foundations of Computational Neuroscience
Springer
William W. Lytton, M.D.
Associate Professor, State University of New York, Downstato, Brooklyn, NY
Visiting Associate Professor, University of Wisconsin, Madison
Visiting Associate Professor, Polytechnic University, Brooklyn, NY
Staff Neurologist., Kings County Hospital, Brooklyn, NY
In From Computer to Brain: ... 阅读全帖 |
|
l*******m
发帖数: 1096 | 27 I think your distance function was defined in a wrong way. Here is an
example
def test_pyfunc_metric():
def dist_func(x1, x2, p):
return np.sum((x1 - x2) ** p) ** (1. / p)
X = np.random.random((10, 3))
euclidean = DistanceMetric.get_metric("euclidean")
pyfunc = DistanceMetric.get_metric("pyfunc", func=dist_func, p=2)
D1 = euclidean.pairwise(X)
D2 = pyfunc.pairwise(X)
assert_array_almost_equal(D1, D2)
I didn't know it before, just checked source codes for you.
... 阅读全帖 |
|
r*****s
发帖数: 184 | 28 the statistical approach is not perfect. But can you have a perfect pairwise
comparison method at all? by the way, your conclusion is worse than the
author's.
Please read carefully
"a new statistical approach summarizing the reproductive performance of ....
(for peer-reviewed publication)"
" But whatever statistical analyses might or might not be used, the data are
always the same and open for everybody to see. This study gives <<
first indication >>>>that the stacked event MON 810xNK603 le |
|
s******s
发帖数: 13035 | 29 你什么也不懂。 不是statistical approach的问题， 而是根本不能这样做比较。
说句你这样外行能听懂的话：就算两组是完全一样的，一起抽出几十组数据分开
比较， 也能有几组显示statistical significant的不同。 统计学家是不能根据
这个做结论的。
pairwise
..
are |
|
T**********e
发帖数: 29576 | 30 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.p
Abstract
We found a relative preference for pinker genital images with redder
genitalia rated significantly less sexually attractive. This effect was
independent of raters' prior sexual experience and variation in female
genital morphology.
Results
We found that men presented with images digitally manipulated to show a
gradation in colour from light pink to red, rated the reddest shade least
attractive. Colour exerted a significant ... 阅读全帖 |
|
q****k
发帖数: 1023 | 31 我也看不大懂。
不确定性 = coefficient of variation (CV) = mean / SD?
参数A,B,C中都是用来预测别的变量，还是三个中一个参数（C?)是被预测或被回归（
dependent variable)?
”大小“说的是平均值？ mean(B) ~ mean(A)/10000?
相关分析不能导出因果关系“C是从B来”。但可以估计C的变动（variance）有多少百
分比是跟B有关的（R^2)。
也许可以试试Pearson correlation
or
Spearman correlation.
把数据画出来？
Pairwise scater plot？ |
|
t****r
发帖数: 702 | 32 it's called Multicolinearity. It is probabily because some columns of the de
sign matrix (age, sex, age*sex) have strong correlations (linearly dependent
),
which inflates standard errors of the coefficient estimator, leading to
insiginificant p-values. In otherwords, age*sex may have contained similar
information as those in age and sex, hence once you include age*sex, then
age and
sex become redundant. You can check pairwise correlations between age, sex
and age*sex to see if there is strong c... 阅读全帖 |
|
t****r
发帖数: 702 | 33 it's called Multicolinearity. It is probabily because some columns of the de
sign matrix (age, sex, age*sex) have strong correlations (linearly dependent
),
which inflates standard errors of the coefficient estimator, leading to
insiginificant p-values. In otherwords, age*sex may have contained similar
information as those in age and sex, hence once you include age*sex, then
age and
sex become redundant. You can check pairwise correlations between age, sex
and age*sex to see if there is strong c... 阅读全帖 |
|
|
I*******l
发帖数: 203 | 35 Are there any additional conditions? If no, then it seems you can not do
this in o(n^2) time. This is because you can construct an array such that
all the pairwise differences are distinct, so there are \theta(n^2) numbers
to output. For example, 1,2,4,8,.... |
|
p*****2
发帖数: 21240 | 36 下边这道题，我优化了半天也不行。有标准求common divisor的快速算法吗？
By 2312 there were n Large Hadron Colliders in the inhabited part of the
universe. Each of them corresponded to a single natural number from 1 to n.
However, scientists did not know what activating several colliders
simultaneously could cause, so the colliders were deactivated.
In 2312 there was a startling discovery: a collider's activity is safe if
and only if all numbers of activated colliders are pairwise relatively prime
to each other (two numbers a... 阅读全帖 |
|
c***7
发帖数: 315 | 37 一个很大的文件 怎么去掉duplicate，怎么回答
hash很耗memory啊，pairwise的话又太慢 |
|
s*******r
发帖数: 2697 | 38 两轮 phone interview
第一轮
亚裔面试官，很nice，很详细问了当前project，问到许多细节的处理
算法题 reverse words in a string.
"It is good"--------->"good is It"
很简单，写完的时候有个bug，让我检查 发现了改了
然后又提示把reverse string的函数单独提出来
follow question问能不能处理 string 前后中许多空白
我说可以 他觉得不可以 我们一块走了一遍code 可以
结束了
第二轮
面试官烙印，交流有问题，至少两处都要求重复了两三遍才听懂
先一个一个的让介绍自己的project 大概20分钟 基本都是我在说
然后开始算法题
Q1
find longest palindrome in a string leetcode原题
解释思路，对每个character 从中间向两边扫 找最长的 他说ok
开始写 写到一半 考虑到偶数的情况，说还要考虑从中间两个character往两边扫
code，然后继续写 还没写完就被烙印打断 说u r on the right trac... 阅读全帖 |
|
s*******r
发帖数: 2697 | 39 两轮 phone interview
第一轮
亚裔面试官，很nice，很详细问了当前project，问到许多细节的处理
算法题 reverse words in a sentence.
"It is good"--------->"good is It"
很简单，写完的时候有个bug，让我检查 发现了改了
然后又提示把reverse string的函数单独提出来
follow question问能不能处理 string 前后中许多空白
我说可以 他觉得不可以 我们一块走了一遍code 可以
结束了
第二轮
面试官烙印，交流有问题，至少两处都要求重复了两三遍才听懂
先一个一个的让介绍自己的project 大概20分钟 基本都是我在说
然后开始算法题
Q1
find longest palindrome in a string leetcode原题
解释思路，对每个character 从中间向两边扫 找最长的 他说ok
开始写 写到一半 考虑到偶数的情况，说还要考虑从中间两个character往两边扫
code，然后继续写 还没写完就被烙印打断 说u r on the right tr... 阅读全帖 |
|
d*********4
发帖数: 5 | 40 更新：
A家今天发信让我on site？！ 可是我是intern啊，我只听说2个电话面试就可以了？什
么情况下intern需要on site？
-------------------------------------------------------------------
之前有过2通电面，后面就没有音信了，以为没戏了。1个月后突然发邮件还要进行一次
电面，刚刚面完，就是介绍一下项目经验，还有做过的东西中比较有challenging的地
方。编程题目比较简单，也都答出来了。准备的较晚，机会不多了，求大家祝福。
(1)Write a function that takes in an arbitrary length singly-linked list and
returns the pairwise reverse of that list. In other words, if I pass in the
list A->B->C->D->E->F the function should return the list B->A->D->C->F->E
(2)有10GB文件 ... 阅读全帖 |
|
e*******8
发帖数: 94 | 41 ElKamina的答案是写的有点不清楚：X[i][j], 我看他的那个表，意思好象是optimum
cost to select j furthest points from {p_1, ..., p_i}, ending at p_i. 所以i
的范围是[2,n]， j的范围是[2,k]. (The cost of a set of points is defined
as the minimum pairwise distance between the points in the set).
所以dp要填的entries有O(nk)个. 我想的实现方法，和你贴的代码差不多，所以最后时
间复杂度是O(n^2 k).
但是又考虑有的dp问题，虽然要填的table也很大，但是有比较快的填法（比如longest
arithmetic progression, 那里table大小是O(n^2), 每个entry用第归公式一个一个
算，也要O(n^3), 但是有比较聪明的方法可以在O(n^2)的时间内填完)....
这个题么，现在我只想出来j＝３的行，O(n)个entry可以在O(n)时间内... 阅读全帖 |
|
m**********j
发帖数: 610 | 42 来自主题: JobHunting版 - 求解面试题 epic，电面，第一轮
给一个2D table，每一个entry是boolean
find rows with most entries in common (could be two or more)
比如说有2行分别是011011， 011010， 在6个column里面有5个相同
没说具体复杂度要求，不过不让对每行做pairwise comparison
对面的三哥说给你半分钟思考
没想出来要hint也不给 |
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m**********j
发帖数: 610 | 43 来自主题: JobHunting版 - 求解面试题
怎么避免行之间pairwise comparison |
|
R******1
发帖数: 58 | 44 来自主题: JobHunting版 - 求解面试题 每一个entry是boolean，不用XOR吧，count多少个true不就好了，这个不算pairwise
comparison吧。 |
|
R******1
发帖数: 58 | 45 来自主题: JobHunting版 - 求解面试题 我完全看错题目了……
也只能想到XOR，肯定是pairwise operation，但不算是comparison吧…… |
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l*n
发帖数: 529 | 46 来自主题: JobHunting版 - 求解面试题 不允许pairwise是指的不能1比2，2比3，1比3这样的全组合吧。 |
|
m**********j
发帖数: 610 | 47 来自主题: JobHunting版 - 求解面试题 epic，电面，第一轮
给一个2D table，每一个entry是boolean
find rows with most entries in common (could be two or more)
比如说有2行分别是011011， 011010， 在6个column里面有5个相同
没说具体复杂度要求，不过不让对每行做pairwise comparison
对面的三哥说给你半分钟思考
没想出来要hint也不给 |
|
m**********j
发帖数: 610 | 48 来自主题: JobHunting版 - 求解面试题
怎么避免行之间pairwise comparison |
|
R******1
发帖数: 58 | 49 来自主题: JobHunting版 - 求解面试题 每一个entry是boolean，不用XOR吧，count多少个true不就好了，这个不算pairwise
comparison吧。 |
|
R******1
发帖数: 58 | 50 来自主题: JobHunting版 - 求解面试题 我完全看错题目了……
也只能想到XOR，肯定是pairwise operation，但不算是comparison吧…… |
|
