question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a question regarding Monte Carlo simulation (direct simulation), applied to propagation of uncertainties.</p>
<p>From what I understand Monte Carlo accepts random numbers of each input variable of the model.</p>
<p>These random numbers are generated with the mean, standard deviation and type of PDF (normal,... | g66992 | [
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<p>I am doing some Kernel density estimation, with a weighted points set (ie., each sample has a weight which is not necessary one), in N dimensions. Also, these samples are just in a metric space (ie., we can define a distance between them) but nothing else. For example, we cannot determine the mean of the sample poin... | g46771 | [
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<p>What non-/semiparametric methods to estimate a probability density from a data sample are you using ?</p>
<p>(Please do not include more than one method per answer) </p> | g66993 | [
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<p>From <a href="http://en.wikipedia.org/wiki/Ancillary_statistic" rel="nofollow">Wikipedia</a></p>
<blockquote>
<p>Given a statistic $T$ that is not sufficient, an ancillary complement is a statistic $U$ that is <strong>ancillary to $T$</strong> and such that $(T, U)$ is sufficient. Intuitively, an ancillary comple... | g66994 | [
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<p>When one wants to compute the correlation of two vectors of a continues variables, one uses pearson (or spearman) correlation.</p>
<p><strong>But what should (can) one use for the case of two vectors with 2 (or 3) ordered levels only? Is spearman enough, or does it require another method?</strong></p>
<p>I rememb... | g7099 | [
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<p>I was given a reduced form VAR model, where the dependent variable is inflation, and independent variables include inflation lagged by four periods (L.Inflation) and other exogenous variables.</p>
<p>The lagged part is the AR component of the model. Shouldn't the AR include L1.Inflation, L2.Inflation, L3.Inflation ... | g66995 | [
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<p>A (non-statistician) colleague has been encountering meta-analyses in papers he reviews for medical journals and is looking for a good introductory level treatment so he can educate himself. Any recommendations? Favorites? Books, monographs, nontechnical survey articles would all be fine.</p>
<p>(Yes, he's famil... | g49773 | [
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<p>We know that due to LD, we can get significant p-values for markers near a causal marker (or a marker closes to the causal region) in <a href="https://secure.wikimedia.org/wikipedia/en/wiki/Genome-wide_association_study" rel="nofollow">GWAS</a> studies. I've seen <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC... | g66996 | [
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<p>The distribition of the rank-sum statistic U is assumed to be normal for large number of samples being considered. What is the exact distribution? I want to compare and sometimes fuse results from various tests wherein some tests might not have large number of samples. I want to have a the exact distributions in cas... | g26315 | [
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<p>How can I generate events using the Poisson distribution in R? The events could be the occurrence of floods in the next 1000 years at a given rate of occurrence per year.</p> | g66997 | [
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<p>I've seen some statement where I got the impression that SVM with a quadratic loss is no more than having a kernel matrix where a multiple of the unit matrix is subtracted from the kernel. It was shown that in the dual problem the L2 loss constant can be merged into the kernel. But it wasn't clear to me. So the ques... | g66998 | [
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<p>Within my logistic regression models I use cross-national data in order to say something about individual soft drug tolerance. In total I have 29 countries with 37.000 individuals.
My supervisor wants me to find some theoretical fundament to the rule of thumb I have used (and she proposed), namely the fact that for... | g66999 | [
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<p>I am looking for references about the theory of linear regression or regression in general. More specifically, I am interested in knowing under what circumstances an estimated regressor is going to give accurate solutions with certain probabiltiy. For now, I am looking for the basic classical results, nothing too fa... | g46778 | [
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<p>it is straight forward to search for purely additive models using the rfe function in caret. Is it possible to include all interactions as part of the search?
In the train method, we can simply say train(Y~.^2, data) to include interactions, but I have not found a way to do this in rfe.</p>
<p>I could probably just... | g67000 | [
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<p>I have a binary logistic regression model with a DV (disease: yes/no) and 5 predictors (demographics [age, gender, tobacco smoking (yes/no)], a medical index (ordinal) and one random treatment [yes/no]). I have also modeled all the two-sided interaction terms. The main variables are centered and there is no sign of ... | g26319 | [
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<p>I'm applying a Hierarchical Agglomerative Clustering (HAC) for grouping my data and I need to determine the number of the cluster automatically. To determine the optimal number of cluster, I obtain the the <a href="http://www.cc.gatech.edu/~hpark/papers/cluster_JOGO.pdf" rel="nofollow">best cluster combination</a> w... | g37428 | [
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<p>For a finite population I have two data sources A and B with variables (X, Y) and (X, Z), respectively. The first data source is actually a full sample, the second is a simple random sample. The items in B cannot be identified precisely using X alone.</p>
<p>I want to combine these data sets using the common variab... | g26321 | [
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<p>I often read the Matthews correlation coefficient is one of the most generally used validity estimates of confusion matrices in machine learning.</p>
<p>However, I couldn't find a reference which states what a good value of this coefficient should be. What is the status on that issue?</p> | g67001 | [
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<p>We have measured reading speed in patients with diabetic eye disease. What we have found is that reading speed is faster in younger patients and in those who has better vision as you would expected. However, we have developed an novel measurement which is much faster to do than measuring reading speed. Both reading ... | g46782 | [
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<p>I want to learn the multiclass boosting technique. I have a basic understanding of binary boosting and also have seen some working examples on this. I have also read about the basics of multiclass boosting algorithms. But I have not been able to search for any examples in multiclass boosting. Can anyone please guide... | g37451 | [
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<p>My friend and I are working on a project on distributed datastructures. We were wondering how much is nearest neighbor information used in modern recommendation systems and whether it would be worthwhile to work on a distributed datastructure (say a kd-tree) for that purpose.</p>
<p>Thanks</p> | g67002 | [
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<p>I have a series of 100 points</p>
<p>My dataset can be found <a href="https://dl.dropbox.com/u/2387762/anomaly.dat" rel="nofollow">here</a> . Each row is a data series. The plot for 90th row is </p>
<p><img src="http://i.stack.imgur.com/yLkq5.png" alt="enter image description here"> </p>
<p>It's easy to detect ou... | g67003 | [
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<p>I have this side project where I crawl the local news websites in my country and want to build a crime index and political instability index.
I have already covered the information retrieval part of the project. My plan is to do:</p>
<ul>
<li>Unsupervised topic extraction.</li>
<li>Near duplicates detection.</li>
<... | g26328 | [
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<p>I would like to plot two time-series on a same graph. One series takes much larger values than the other, so I thought a semilog scale might be appropriate (i.e. linear X (dates) and log Y). However, both series take on negative and positive values. Does it still make sense to use a log scale? If so, should I transf... | g67004 | [
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<p>About simple regression:</p>
<p>It's well known that usual OLS estimators of $β_{0}$ and $β_{1}$ have minimum variance of all unbiased linear estimators. </p>
<p>I wonder if there are popular biased linear estimators which have smaller variance or unbiased nonlinear estimators or biased nonlinear estimators which ... | g45678 | [
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<p>I'm currently using R to find the best approach to solving a machine learning problem. Once I've got the approach sorted, I will need to build this into an application which can be used by end users. My background is as a .NET developer. I see there are a few questions related to this, but my question is more about ... | g67005 | [
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<p>Let's imagine we have one variable (factor.to.explain) that we want to explain by 10 other variables using 10 linear model (no interactions computed). We should correct for multiple testing. It is possible that one, some or several of them affects the factor.to.explain.</p>
<p>Note: TP = True Positive, FN = False N... | g67006 | [
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<p>I want to cluster a set of time series regarding their pairwise correlation. If I normalize the series by subtracting their average value and then scaling to a standard deviation of one, the correlation coefficient (Pearson's r value) between original series is the same as the dot product of the normalized counterp... | g26331 | [
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<p>I'm trying to compare a few regression models for my data. For linear regression everything is quite understandable, but robust and quantile regressions are not so obvious. I could not find almost anything about calculating confidence interval for these regression models unless I looked for something wrong.</p>
<p>... | g45694 | [
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<p><a href="https://en.wikipedia.org/wiki/Hilbert_curve" rel="nofollow">Hilbert Curves (Wikipedia)</a> are space-filling curves said to "fairly well preserve locality".</p>
<p>Do you know any <em>theoretical</em> results here, such as bounds that neighbors within a radius of $\varepsilon$ are preserved with probabilit... | g67007 | [
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<p>I'm stuck with a regression modeling problem. I have panel data where the dependent variable is a probability. Below is an excerpt from my data. The complete panel covers more countries and years, however it is unbalanced. What I can observe is the number of events and the number of trials. The event probability was... | g67008 | [
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<p>I have a data set of 13 attributes where some are categorical and some are continuous (can be converted to categorical). I need to use logistic regression to create a model that predicts the responses of a row and find the prediction's accuracy, sensitivity, and specificity.</p>
<ul>
<li>Can/Should I use cross vali... | g46791 | [
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-0.019399477168917656,
-0.0018507124623283744,
0.05899317190051079,
-0.05482251197099686,
-0.005768836475908756,
0.01882403902709484,
0.016106940805912018,
0.05962169170379639,
-... |
<p>I have seen the terms "frequent pattern mining", "subspace clustering", and "biclustering". They all pertain to finding clusters using subsets of the data attributes. What's the difference?</p> | g26334 | [
0.06238781660795212,
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0.034365974366664886,
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0.03964238986372948,
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0.013833390548825264,
0.004730080720037222,
0.10075981169939041,
-0.025... |
<h3>Background</h3>
<p>I am writing a systematic review and meta-analysis of the association of exposure to X with the outcome Y. I have identified ten studies that report on this subject. This will be a meta-analysis of the published literature, not of individual participant data. I want to report the overall mean ag... | g7170 | [
-0.008414171636104584,
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0.04684235155582428,
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0.0601106695830822,
0.0... |
<p>Does sample size influence the underlying distribution of population, i.e., the bigger the sample you generate the more it resembles whatever distribution of the population it's drawn from?</p>
<p>What would you say are the key factors for measuring the quality of a given sample with regards to its fitting to the d... | g67009 | [
0.02017691358923912,
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0.051608260720968246,
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0.04541872441768646,
... |
<p>To strengthen my understanding of fundamental probability theory, I am working my way through <a href="http://www.dgp.toronto.edu/~hertzman/ibl2004/" rel="nofollow">Professor Aaron Hertzmann's <em>Introduction to Bayesian Learning</em> course notes</a>. Section 3.8 of these course notes includes the following exerci... | g37533 | [
0.022946931421756744,
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0.001082386588677764,
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0.02414834499359131,
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0.04626292362809181,
0.011849735863506794,
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-0.011889806017279625,
-0.006288575474172831,
0.02936595305800438,
0.030238816514611244,
0.... |
<p>I am looking at the Wikipedia entry for <a href="http://en.wikipedia.org/wiki/Empirical_Bayes_method" rel="nofollow">empirical Bayes</a>, but it's a bit confusing - it seems to me the solution must apply only to the case in which there's only $n=1$ sample $y$ for each $\theta$ and the "sample mean" that's referred t... | g67010 | [
0.0032331182155758142,
0.00807495228946209,
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0.019570617005228996,
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-0.009147688746452332,
-0.04113737866282463,
0.035922594368457794,
-0.01323827262967825,
... |
<p>I'm reading through Fan's <a href="http://orfe.princeton.edu/~jqfan/papers/01/penlike.pdf" rel="nofollow">SCAD paper</a> and I feel like I'm not getting a simple step. On page 1354 where he is talking about quadratic approximations to a penalty function he has</p>
<p>$$\left[\rho_\lambda(|\beta_j|)\right]' = \rho'_... | g67011 | [
0.042163047939538956,
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0.00628989702090621,
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-0.00837593711912632,
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0.04221915453672409,
0.006766429170966148,
0.... |
<p>I was was wondering about where to track down implementation details for SAS: I have certain outputs (depending on small amounts of data) which I would like to understand better by trying to check against a theoretical solution. I'm looking at something pretty specific (how standard errors on predicted probabilities... | g26340 | [
0.040708690881729126,
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-0.08543602377176285,
0.011383486911654472,
0.008081561885774136,
0.08555097132921219,
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<p>I'm using GPML (Gaussian Processes for Machine Learning) v3.2 in Matlab.</p>
<pre><code>meanfunc = @meanConst; hyp.mean = 0;
covfunc = @covSEard; ell = 1.0; sf = 1.0; hyp.cov = log([ell*ones(1,size(xtr,2)) sf]);
likfunc = @likGauss; sn = .1; hyp.lik = log(sn);
inffunc = @infLOO;
hyp = minimize(hyp, @gp, -4*40, inff... | g49345 | [
0.0022200215607881546,
0.002391439862549305,
0.0006863392773084342,
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0.0660056620836258,
0.02662505954504013,
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0.024526355788111687,
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-0.023634381592273712,
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0.02660350501537323,
0.06689271330833435,
0.066... |
<p>I have many articles and they have headlines and body text. I am trying to deduce a way to identify with some (ideally)high degree of probability if 2 articles are about the same thing. </p>
<p>One example of a probable match here would be two news articles from two separate publications discussing a natural disast... | g7177 | [
0.07337090373039246,
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0.010913711041212082,
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<p>I am doing a project where I would like to predict some characteristics from large data set and I am expecting that I would should use some Machine Learning techniques, but not sure how to proceed.
I have a background in Econometrics, but I have not really done projects like this before.</p>
<p>I have a large data ... | g67012 | [
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0.0494987778365612,
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0.0849362388253212,
0.05... |
<p>I want to sample from mixed normal distribution, first one is $N(1,2)$, second one is $N(5,4)$. I used <code>rnorm(100, c(mean=c(1,5), sd=c(2,4)))</code>. Is this correct?</p>
<p>The problem I am trying to solve is sampling from the 2 distribution above, first one with 75%, second one with 25%. Am I on the right t... | g67013 | [
0.02636897563934326,
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0.013169392943382263,
0.034323763102293015,
0.010233161970973015,
0.005611995700746775,
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<p>I'm coding up a monte-carlo analysis; I've got a deterministic model that depends on parameters that are uncertain. One of those uncertain parameters is a partially-observed vector of prices by country -- I want to predict missing values in a manner similar to what is used in multiple imputation via chained equatio... | g67014 | [
0.022735122591257095,
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0.0016420455649495125,
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0.00720912916585803,
0.0795351192355156,
... |
<p>I am running kmeans to identify clusters of customers. I have approximately 100 variables to identify clusters. Each of these variables represent the % of spend by a customer on a category. So, if I have 100 categories, I have 100 variables such that sum of these variables is 100% for each customer. Now, these varia... | g26345 | [
0.007397353183478117,
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0.011842196807265282,
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0.03448519483208656,
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0.0355701744556427,
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0.016513962298631668,
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0.015690328553318977,
0.020339354872703552,
0.0... |
<p>Can someone give me detailed instructions how to install and use fGarch? Eg. I would like to find the MLE parameter estimates for a skew normal dist using it - could someone give me instructions up to that point?</p> | g26346 | [
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0.0014778261538594961,
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<p>I want to check if a new equipment improves a score compared with the older equipment. My database contains the score with the old equipment, and the scores with each new equipment. I googled, userR'd, checked similar journal articles and saw that <a href="http://onlinelibrary.wiley.com/doi/10.1111/anae.12075/full" ... | g13869 | [
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... |
<p>I am learning about building linear regression models by looking over someone elses R code. Here is the example data I am using:</p>
<pre><code>v1 v2 v3 response
0.417655013 -0.012026453 -0.528416414 48.55555556
-0.018445979 -0.460809371 0.054017873 47.76666667
-0.246110341 0.092230159 0.05743596... | g49310 | [
0.008535681292414665,
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0.05377371609210968,
0.028070198372006416,
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-0.02655281312763691,
-0.027192270383238792,
0.05133362486958504,
0.059331364929676056,
... |
<p>I just ran an extended SVC gridsearch in libsvm on about 9000 multi-dimensional vectors representing a time series. Here are the highest scoring results:</p>
<pre><code>[local] 3 -7 72.4729 (best c=0.5, g=0.5, rate=76.9618)
..
[local] -1 -5 71.79 (best c=8.0, g=0.5, rate=77.4432)
..
[local] 15 -11 73.0326 (best c=2... | g67015 | [
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0.006489538121968508,
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0.027509275823831558,
0.03729640692472458,
-0.0006374984513968229,
0.038782477378845215,
... |
<p>I was wondering how ML is defined when the parameter does not completely specify the model. More concretely, suppose $X_1, X_2, \cdots, X_n$ are drawn iid such that $P(X_1=i)=\theta_i$, $ 1 \leq i \leq k$. I want to find the ML estimate of $\phi= \max_{1 \leq i \leq k} \theta_i$. To me it is not even clear if the ML... | g67016 | [
-0.011858079582452774,
0.0020704271737486124,
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0.036339692771434784,
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0.023415319621562958,
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0.023012612015008926,
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0.001928777084685862,
0.04409858211874962,
0.... |
<p>Frequently I see artificial neural networks compared by their "classification error rates" or "error rates", particularly for multi-class problems like CIFAR-10. What does this error rate actually refer to? Hamming loss? How is it calculated?</p> | g23480 | [
0.015497726388275623,
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0.004608497954905033,
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0.028440067544579506,
0.12897048890590668,
0... |
<p>In the mixed Poisson regression model, with vector of random effects $w \sim N(0, \Sigma)$, how are the parameters in $\Sigma$ estimated? Is it the same REML method as in the linear mixed model?</p> | g23481 | [
0.023766858503222466,
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0... |
<p>I am trying to better understand the connection between the power law distribution and Zipf's distribution (law). There is a neat explanation in [1].</p>
<p>The article suggests that as we can derivate the power law function from Pareto's law, combined with the relationship between Pareto's law and Zipf's law, the ... | g67017 | [
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0.050457440316677094,
0.... |
<p>I have two linear regression models (with the same predictors) that try to estimate two different (although related) features of the same population. I am analyzing the hypothesis that these predictors are not as good for the second feature as they are for the first.
Indeed, the RMSE of the second model is 7% worse ... | g26352 | [
0.05589648708701134,
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-0.02201569452881813,
0.050467487424612045,
0.03354113548994064,
0.060420673340559006,
0.011... |
<p>I am doing an analysis of items (I1, I2, I3, etc.). The items could be either correctly answered (1) or incorrectly answered (0). Visually, most of the participants answered the items correctly. I want to know whether each of the items was different from 1. I thought to run a Wilcoxon signed rank test for each of th... | g67018 | [
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0.0054028332233428955,
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0.004074591677635908,
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0.00981848780065775,
-0.006386118941009045,
0.04700417444109917,
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... |
<p>I have been looking for a function that can make recursive window out-of-sample forecasts, but seems there is none. So I'm thinking about about making a function that can be used for recursive window forecasting in an ARIMA model. However I know little about programming, so I'm seeking for help.</p>
<p>What I want ... | g26354 | [
0.017551645636558533,
0.008746507577598095,
0.025375021621584892,
0.007215564139187336,
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0.018046053126454353,
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0.028403248637914658,
0.057331882417201996,
0.058627400547266006,
0.041688863188028336,
0... |
<p>After burn-in, can we directly use the MCMC iterations for density estimation, such as by plotting a histogram, or kernel density estimation?
My concern is that the MCMC iterations are not necessarily independent, although they are at most identically distributed. </p>
<p>What if we further apply thinning to the M... | g67019 | [
0.03275454416871071,
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0.002193760359659791,
-0.00704145897179842,
0.0027560291346162558,
0.0924774706363678,
0.0... |
<p>I am looking for regression techniques which are similar to Kriging/Gaussian process regression, in that no explicit model needs to be specified. (Discounting the prior over functions) I have three independent variables and one dependent variable to which I want to apply such a procedure. The independent variables s... | g67020 | [
-0.002332765841856599,
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0.01756485365331173,
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-0.042505279183387756,
0.05955248698592186,
0.0029708375222980976,
0.0393999889492988... |
<p>I have a response variable and 10 predictor variables (all ordinal). I wanted to see if there was any evidence of a relationship between the response and predictors. I used a two proportion z-test to see if there was a significant difference in my predictor at the two different levels of my response. I did this for ... | g26356 | [
0.019989371299743652,
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0.015055887401103973,
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0.023324599489569664,
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-0.05715959519147873,
0.06106363981962204,
-0.019028110429644585,
0.06833762675523758,
0.... |
<p>If I have data of length <code>n</code> and want to generate a random sample of length <code>N</code>, does the following use of the <code>prob</code> argument make each observation equi-probable? </p>
<pre><code>random.sample = sample(mydata, N, replace=TRUE, prob=rep(1/n, times=n))
</code></pre>
<p>As an exam... | g26357 | [
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0.07219935953617096,
0.0... |
<p>I have data from about 250 self-injurers and would like to cluster analyze their reported motivations for self injury (and then explore cluster membership vis-a-vis various psychological measures). I have scores on 9 motivation scales which are likert-type but non-normal ($\log_{10}$-transformations yield <1 skew... | g67021 | [
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-0.01016659289598465,
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0.012210811488330364,
0.04660681262612343,
-0... |
<p>I'm reading Hayashi's "Econometrics", and in Chapter 2, page 101 he discusses the following white noise process:
<img src="http://i.stack.imgur.com/BncMb.png" alt="enter image description here"></p>
<p>I understand the calculations for the expected mean and variance, but I can't understand why the covariance would ... | g67022 | [
0.03931247070431709,
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0.03928398713469505,
0.004844664596021175,
0.0423... |
<p>I am trying to improve accuracy of my logistic regression model by selecting the best features. I did an FPR test and ranked the features based on their F-score. </p>
<p>The problem is that selecting the best say 3 features doesn't perform as well due to what I suspect is a cross correlation between these features.... | g29509 | [
0.012615814805030823,
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0.028214475139975548,
0.002519358182325959,
-0.05090641975402832,
-0.01601053774356842,
0.029591750353574753,
0.0033357723150402308,
0.022943466901779175,
-0... |
<p>Is anyone aware of propensity score matching methods for when there are more than 2 treatment groups? I am working on a project with 4 treatment groups: </p>
<ol>
<li>A</li>
<li>B</li>
<li>A and B</li>
<li>Neither A nor B</li>
</ol>
<p>Calculating propensity scores using multinomial logistic regression might work,... | g67023 | [
0.01225878857076168,
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0.03758344426751137,
-0.0009554391144774854,
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0.... |
<p>If I have a binomial maximum likelihood function</p>
<p>$$ L(\theta | k) = \Pi_i^N p(\theta)^{k_i}(1-p(\theta))^{(n_i-k_i)}$$ </p>
<p>I know that the index terms can be made into a sum, simplifying the expression for calculation purposes. I have a model which predicts the probability of success as a function of a ... | g46827 | [
-0.02111845277249813,
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0.015367774292826653,
-0.05862698704004288,
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0.01857423596084118,
... |
<p>the likelihood of a model is defined as the probability of data given model:</p>
<blockquote>
<p>Likelihood(Model) = p(DATApoints | Model)</p>
</blockquote>
<p>which is equivalent to the product of all p(datapoint | Model) for each datapoint in DATApoints.</p>
<p>so, to get the likelihood of a model given norma... | g589 | [
-0.013649126514792442,
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0.01546502485871315,
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-0... |
<p>I've been asked to replicate a study that models an accelerated failure time survival model with a log-logistic distribution and gamma distributed frailty (a 'log-logistic shared gamma frailty model') estimated with the streg command in Stata [1]. We have made some changes to the original model and now want to estim... | g67024 | [
-0.04939409717917442,
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0.04836132749915123,
0.00... |
<p>Asking a question essentially for a colleague, since it's far enough afield of what I do that I want to make sure I don't lead her astray:</p>
<p>Assume a study with 5 factors and 3 dependent variables - we'd like to test the effect of interaction between any two factors on a given dependent variable (for Factor A ... | g26368 | [
0.0036139485891908407,
0.003926772158592939,
0.020866218954324722,
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0.012851176783442497,
0.004439209122210741,
-0.020520642399787903,
... |
<p>I have two groups A and B, each of which consists of 5 samples. Each sample is described in a vector of length (>1000) of continuous numeric values (characteristics). I want to test if the sample in the first group varies between each other more than the sample in the second group. </p>
<p>I tried one-way ANOVA for... | g67025 | [
-0.015222727321088314,
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0.010153662413358688,
0.012961416505277157,
-0.01922341808676719... |
<p>I am encountering a difficulty with the following task. Have I made a mistake, or is this an inherent flaw in the notion of confidence intervals? (Other such flaws exist.)</p>
<p>Consider a random sample $X_1,\ldots , X_n$ from a Uniform($\theta$, $\theta + a$) distribution, where $\theta$ is unknown and $a$ is k... | g26369 | [
-0.011541472747921944,
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0.012027516961097717,
0.020279446616768837,
0.04083789139986038,
-0.00937966350466013,
-0... |
<p>I am trying to fit a spherical variogram to some synthetic data using the code available at <a href="http://www.mathworks.com/matlabcentral/fileexchange/25948-variogramfit" rel="nofollow">http://www.mathworks.com/matlabcentral/fileexchange/25948-variogramfit</a>. However, I have some doubts. I simulated some synthet... | g67026 | [
0.028652040287852287,
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-0.014594092033803463,
0.00020484047126956284,
0.02218448929488659,
0.02387748844921589,... |
<p>I would like to create a chart like the one on the left <a href="http://www.cdec-decoder.org/concepts/alignment.html" rel="nofollow">here</a> in order to visualize maximum probabilities:</p>
<p><img src="http://i.stack.imgur.com/0GUgv.png" alt="enter image description here"></p>
<p>Is there a name for this type of... | g26372 | [
-0.02967311628162861,
-0.00861806608736515,
-0.020058920606970787,
-0.08008788526058197,
-0.01538427360355854,
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0.004907986614853144,
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-0.06269406527280807,
0.0418173186480999,
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0.11269170045852661,
-0.0... |
<p>I found <a href="http://www.statmethods.net/advstats/cluster.html" rel="nofollow">this tutorial</a>, which suggests that you should run the scale function on features before clustering (I believe that it converts data to z-scores).</p>
<p>I'm wondering whether that is necessary. I'm asking mostly because there's a ... | g67027 | [
0.002435373840853572,
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0.009832533076405525,
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0.04150692746043205,
0.07501477748155594,
0.0168... |
<p>Please can you check if am I correct?</p>
<p>I have a random variable $X$ normally distributed with mean $\mu$ and variance $\sigma^2$.
I generate two independent sample $T_1$ and $T_2$ with $T_1 < T_2$ where
$\bar{X}_1$ and $\bar{X}_2$ are the sample means respectively.</p>
<p><strong>1)The proposed estimators... | g67028 | [
-0.0034812800586223602,
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0.0045393081381917,
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0.027653884142637253,
0.0005918421666137874,
0.018228380009531975,
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0.027659716084599495,
0.0065647270530462265,
0.04897104203701019,
-0.06520773470401764,
... |
<p>I'm using JMP to analyze some sample data to make predictions about the population. My sample is from a destructive QC test, so I obviously want to minimize my sample. I have a response (my Y) and a known factor (a very strong and consistent correlation that is measurable by non-destructive means) but the exact re... | g46836 | [
0.03500964120030403,
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0.016274070367217064,
0.019079945981502533,
-0.... |
<p>I'm designing a web service that will predict and recommend new items a user might like based on their expressed preferences on previous items (simple thumbs up/down interface). </p>
<p>I was told to look into decision trees, since they're a simple way to group things based on their characteristics, and they can be... | g26374 | [
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0.03371978551149368,
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0.013374747708439827,
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0.06568016111850739,
... |
<p>I'm currently analyzing data from a series of behavioral experiments that all use the following measure. The participants in this experiment are asked to select clues that (fictitious) other people could use to help solve a series of 10 anagrams. The participants are led to believe that these other people will eithe... | g46838 | [
-0.03525528684258461,
0.030298156663775444,
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0.0010505038080736995,
-0.003587481565773487,
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-0.02815268374979496,... |
<p>I have been working with <code>glm.nb</code> from <code>MASS</code> package for quite a while now. However, there are somethings I seem to not quite able to get my head around. Suppose I have a data that looks like this:</p>
<pre>
Expression Species timePoint Replicate
40 A T1 R1
60 ... | g26375 | [
0.026823217049241066,
-0.06737057864665985,
-0.013688495382666588,
0.01458632480353117,
0.001545635866932571,
0.02524322085082531,
0.06559165567159653,
0.009167714975774288,
-0.11038439720869064,
0.018247101455926895,
-0.06410588324069977,
0.04913022741675377,
0.028995446860790253,
-0.0153... |
<p>From my research findings/results it was clear that lecturers and students use different web 2.0 applications. But my null hypothesis result is contradicting this one of my null hypotheses is 'there is no significant difference between the web 2.0 application commonly used by students and those used by lecturers'.</... | g26377 | [
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-0.08504213392734528,
0.023352984338998795,
0.04404144734144211,
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0.06280834972858429,
0.0034073451533913612,
0.004129126667976379,
-0.058176279067993164,
0.014864829368889332,
-0.005518775433301926,
0.04526215046644211,
0... |
<p>SPSS Warning
The large number of columns in the design matrix will cause integer overflow. The large number of columns may be due to too many levels in one or more factors, or to higher-order interactions among factors with many levels. It may also be due to too many factors This command is not executed.
How do I re... | g67029 | [
0.018153462558984756,
0.06790989637374878,
0.0000576956408622209,
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0.010145493783056736,
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0.046326518058776855,
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-0.057884346693754196,
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0.0030241073109209538,
0.05725478753447533,
0... |
<p>Unbiased weighted variance was already addressed <a href="http://stats.stackexchange.com/questions/47325/bias-correction-in-weighted-variance">here</a> and <a href="http://www.analyticalgroup.com/download/WEIGHTED_MEAN.pdf" rel="nofollow">elsewhere</a> but there still seems to be a surprising amount of confusion. T... | g26379 | [
0.02977941371500492,
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0.01594466157257557,
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0.009366750717163086,
0.0004803176561836153,
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-0.033871956169605255,
0.027057824656367302,
0.021859223023056984,
0.019421441480517387,
0... |
<p>I have a dataset of text messages of which I'm trying to filter out the spam from the legitimate ones. I have roughly 4600 pieces of data spread among 57 features and then their classification as spam or not. I have four 'versions' of the data, one the regular data and the other three I have applied various types of... | g26380 | [
0.04717213660478592,
-0.037908487021923065,
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0.085537388920784,
0.0012896480038762093,
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0.006166212726384401,
-0.04330821335315704,
0.0338687002658844,
0.005792043171823025,
-0.025... |
<p>Suppose we have a supervised training set $T=\{ (x_1, y_1),\dots, (x_n,y_n)\}$ where $x_i$ is an example and $y_i \in \{-1,+1\}$ is its label. Further suppose that examples are only observable through a feature extraction function $f(x;s)$ where $x$ is an example and $s \in \{s_1,\dots,s_m\}$ is an argument for fea... | g38026 | [
0.003608045633882284,
0.0013028865214437246,
0.02151687815785408,
0.025995932519435883,
0.030859967693686485,
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0.024567317217588425,
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0.0047922334633767605,
0.02060740441083908,
0.04389418661594391,
0.059666913002729416,
0.005... |
<p>Autocorrelation is defined as $\rho(\tau)=E((x_i-\mu)(x_{i+\tau}-\mu))/\sigma^2$ which should have a value between $\pm1$.</p>
<p>However, what if both $x_i$ and $x_{i+\tau}$ are significantly larger than $\mu$? Would it not be possible to have correlation greater than one? I'm particularly thinking about large lag... | g67030 | [
0.0485236793756485,
0.015960868448019028,
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-0.0001685412717051804,
0.067491814494133,
0.010694782249629498,
-0.0... |
<p>I have two sets of vectors, <code>A</code> and <code>B</code>. Vectors from set <code>A</code> live in an m-dimensional space, while those from set <code>B</code> are n-dimensional. </p>
<p>I also have a mapping <code>f</code> from <code>A</code> to <code>B</code>. I would like to learn an <code>n x m</code> matrix... | g67031 | [
-0.012087845243513584,
-0.032236840575933456,
-0.017691928893327713,
0.011226446367800236,
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-0.019169410690665245,
-0.014908741228282452,
0.015780974179506302,
0.05828153342008591,... |
<p>I'm working on a behavoural scorecard modelling exercise, and many of the decisions taken to date have been based on the experience of a consulting credit analyst (whose experience software-wise is SAS) as I am primarily in BI. So far I have:</p>
<ul>
<li>a linux pc with 32gb of ram and an i7 processor</li>
<li>an ... | g67032 | [
-0.00017247212235815823,
-0.03654095530509949,
-0.002258173655718565,
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0.024068493396043777,
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-0.03324785456061363,
0.021438756957650185,
0.012675552628934383,
0.04378565773367882,
... |
<p>False discovery rate (FDR) is defined as</p>
<blockquote>
<p>FDR = FP / (TP + FP).</p>
</blockquote>
<p>Does it estimate some population quantity, independent of sample, when the sample satisfies some condition?</p>
<p>To make it clearer, True positive rate is defined as </p>
<blockquote>
<p>TPR = TP/ (TP + ... | g26383 | [
0.051811959594488144,
0.016278449445962906,
0.002456785412505269,
-0.016035540029406548,
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-0.010885000228881836,
0.024947911500930786,
0.005584226455539465,
0.04732459411025047,
... |
<p>In order to help interpret fitted models — especially those with interaction terms and non-linear components — I've found it useful to plot predicted values of a dependent variables for what we might think of as <em>prototypical individuals</em>. I would like to know if there are existing R modules that help do this... | g26385 | [
-0.014531806111335754,
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-0.020124757662415504,
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0.014731629751622677,
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-0.011791416443884373,
0.03551670163869858,
0.017861951142549515,
0.02552621252834797,
0.... |
<p>I have two beta-distributions:</p>
<p>$H_1 = Beta(\alpha_1, \beta_1) $</p>
<p>and</p>
<p>$H_2 = Beta(\alpha_2, \beta_2) $</p>
<p>(parameters are known), and I'd like to estimate whether a new sample $D$ rather comes from $H_1$ or $H_2$.</p>
<p>It seems that Bayes factor is the solution</p>
<p>$K = \frac{\int \... | g7383 | [
-0.0050457497127354145,
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-0.02569424733519554,
0.04754660278558731,
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0.032311420887708664,
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-0.018453378230333328,
-0.050393279641866684,
0.0487181693315506,
0.05152973160147667,
... |
<p>First a note: I am not a statistician. I studied maths at university (but opted out of every single stats class), and now find myself in a job where I'm doing stats.</p>
<p>My question is a little bit philosophical, and I'm sure that I have my brain in a twist by thinking too hard about the wrong things, but I'm st... | g67033 | [
0.008420554921030998,
0.02076786756515503,
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0.027114013209939003,
-0.004107901360839605... |
<p>I conducted a GLMM analysis in SPSS with <code>y~a+b+a*b</code>. </p>
<p>The output result contains two tables: </p>
<ol>
<li><p>the fixed effects, for which the main effects and the interaction are significant; </p></li>
<li><p>the fixed coefficients, for which the significance changes according to the order of <... | g67034 | [
0.019770581275224686,
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0.0685713142156601,
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-0.02331165410578251,
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0.04127795994281769,
0.04961845651268959,
0.02007... |
<p>Consider the mean squared error $$\text{MSE}(x_0) = E_{T}(f(x_0)-\hat{y}_0)^{2}$$ $$ = E_{T}(\hat{y}_0-E_{T}(\hat{y}_0))^{2}+(f(x_0)-E_{T}(\hat{y}_0)^{2})$$</p>
<p>Is the first term after the equal sign in the second line basically saying the following: Get an estimate and find its deviation from the average estim... | g67035 | [
-0.02694234997034073,
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0.012778946198523045,
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0.07162730395793915,
0.055829960852861404,
0.0... |
<p>My task is to assess how various environmental variables affect annual population fluctuations. For this, I would use a model like:
$$
\mbox{log} ( \mu_{i,j+1} ) = \mbox{log} ( \mu_{i,j} ) + R_{j} + \sum\limits_{k} \alpha_k x_{k,j} \\
N_{i,j} \sim \mbox{Poiss} ( \mu_{i,j} )
$$
Where $N_{i,j}$ is number of observed ... | g67036 | [
-0.002431168220937252,
-0.051098961383104324,
-0.00877100508660078,
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-0.012083868496119976,
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0.0017823895905166864,
0.012449140660464764,
... |
<p>I'm using Poisson loglinear regression (from Generalized Linear models, SPSS) to analyze different patient variables that influence LNT-lymph node yield-(poisson distribution).
After removing the main effects from the model that did not influence the outcome I tried looking for possible interactions. I used the Like... | g12508 | [
0.002075781114399433,
-0.03760464861989021,
-0.016013361513614655,
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0.01750044710934162,
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0.005433418322354555,
0.0059643154963850975,
0.035795364528894424,
0.04734276980161667,
0... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/25190/naive-bayes-for-two-continuous-features">Naive Bayes for two continuous features</a> </p>
</blockquote>
<p>I've seen that Multinomial Naive Bayes classifier in <a href="http://scikit-learn.org/stable... | g49764 | [
-0.007345325313508511,
-0.036955952644348145,
0.030531860888004303,
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0.044282279908657074,
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0.012324546463787556,
0.0044541568495333195,
0.028733352199196815,
... |
<p>Suppose we have data $x_i, i=1,2,3,...n$ that are <em>dependent</em> and identically distributed with marginal $f(\cdot|\alpha)$. If we model this with the likelihood</p>
<p>$
L = c(F(x_1|\alpha),F(x_2|\alpha),...F(x_n|\alpha)|\theta)\prod_{i=1}^n f(x_i|\alpha)
$</p>
<p>and the dependence parameter $\theta$ is kno... | g67037 | [
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0.004739304538816214,
0.015100047923624516,
0.023167140781879425,
0.012375209480524063,
... |
<p>I have a model with two variables $X_1$ and $X_2$.</p>
<p>In general, I would like to create a Gibbs sampler based on the conditionals $p(X_1 | X_2)$ and $p(X_2 | X_1)$.</p>
<p>However, computing either $p(X_2 | X_1)$ or $p(X_1 | X_2)$ is intractable. Though, they can be computed up to a normalization constant.</p... | g67038 | [
0.004362547770142555,
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0.0037414636462926865,
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0.03602089732885361,
-0.019020719453692436,
... |
<p>If the distance correlation (ref. Gabor J. Szekely) $R_n(X,Y)>R_n(Z,Y)$ would the expected generalization error of a prediction model over $(Z,Y)$ be lower than $(X,Y)$ in predicting $Y$, where $Z$, $X$ are features? </p> | g67039 | [
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0.031223144382238388,
0.0339910052716732,
... |
<p>I have the following model:
$y \sim b_0 + b_1x_1 + b_2x_2 + b_3x_1x_2$.</p>
<p>$x_1$ is a factor with 2 levels (0 and 1), and $x_2$ is a factor with 3 levels.</p>
<p>I know that to calculate standard errors for the interaction term I should use
$\sqrt{\text{var}(b_1) + \text{var}(b_2) + 2\text{cov}(b_1,b_2)}$. </... | g26395 | [
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0.023113684728741646,
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0.050683245062828064,
0.003582446603104472,
-0.01... |
<p>Suppose we have a multivariate hypergeometric distribution on balls in $k$ colors. Let $n_i$ be the number of balls for the $i$-th color, so that we are drawing from $N = \sum_i n_i$ balls. Each sample for this experiment consists of drawing 30 balls from the urn. Finally, suppose we are given a function which ma... | g67040 | [
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0.0167014729231596,
0.006786363665014505,
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0.009309750981628895,
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-0.03159690275788307,
-0.06044967845082283,
0.007296318653970957,
0.06524915993213654,
0.06943... |
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