question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I'm trying to devise a prior for a model parameter $x$ about which I know the following things:</p>
<ol>
<li>It is strictly positive.</li>
<li>There is a maximum possible value $x_m$.</li>
<li>Larger values are less likely than smaller ones.</li>
</ol>
<p>In terms of a probability distribution $P(x)$, I interpret ... | g65509 | [
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<p>I would like to ask you about methods of converting a discrete time Markov chain, represented by a fully known transition matrix, into a relatively small set of transition rules.</p>
<p>For example, let there be a transition matrix:</p>
<p>$$
\left(\begin{array}{cccc}
1-m & m & 0 & 0 \\
u & 1-u-m &... | g65510 | [
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<p>I am using <a href="http://scikit-learn.org/stable/modules/generated/sklearn.metrics.confusion_matrix.html" rel="nofollow">confusion matrix</a> to check the performance of my classifier. </p>
<p>I am using Scikit-Learn, I am little bit confused. How can I interpret the result from </p>
<pre><code>from sklearn.met... | g24105 | [
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<p>I want to learn Gibbs sampling for a Bayesian model. How can I sample the variable from the conditional distribution?<br>
<img src="http://i.stack.imgur.com/ca6T4.gif" alt="a Bayesian model"><br>
In this example, arrow means dependent; for example, <code>Grade</code> depends on <code>Difficulty</code> and <code>Int... | g65511 | [
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<p>As detailed on its Wikipedia page, <em>Mutual information</em>, $I(X,Y)$, can be bounded by the Jensen inequality to show that it is always positive. Also, one can show that
$$ I(X,Y) = H(X) - H(X|Y). $$
Together this implies that
$$H(X|Y) < H(X). $$
If seen through Bayes Rule, this implies that information on $X... | g65512 | [
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<p>This is maybe annoyingly easy for some, but I am completely new to regression.</p>
<p>As an example, I shall use the data set in R, called <code>mtcars</code>. I am interested in the columns <code>cyl</code>,<code>drat</code>,<code>gear</code> and <code>carb</code>, and will try to model <code>cyl</code> using Pois... | g65513 | [
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<p>I've inherited a survey from an old employee that consists of 27 questions. We have on the order of 500 respondents but not all of them answered every question as some questions are of the type 'if yes then please answer this'. The survey has an overall reported margin of error of +/- 4% at the 95% confidence interv... | g65514 | [
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<p>This is a model that is used to model soccer scores, so $i$ and $j$ are, respectively, home and away teams. Random variables $(x,y)$ are the goals scored by the home and away teams, respectively. Parameter $\lambda$ is a known mean goals scored by the home team and $\mu$ is the mean goals scored by the away team. I ... | g65515 | [
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<p>I have the data from 12 patients and I know the responders and the non responders. I already have calculated some markers from each one and plotting histograms and pdfs it seems that they can be distinguished (histograms of responders are shifted to the left, which I was expecting).</p>
<p>I also calculated some st... | g65516 | [
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<p>I'm building a mixture model consists 2 normal distribution:</p>
<p>\begin{equation}
X_1 \sim \mathcal{N}(\mu_1,\sigma_{1}^{2}), \quad X_2 \sim \mathcal{N}(\mu_2,\sigma_{2}^{2})\end{equation}</p>
<p>while</p>
<p>$$pdf(x) = p_1 N(x, \mu_1, \sigma_1^2) + p_2 N(x, \mu_2, \sigma_2^2)$$</p>
<p>where $p_1+p_2=1$, </p>... | g65517 | [
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<p>I want to design a web application which would show whether a person is busy or not. For this, I already have data with the user-name, the busyness factor and the time stamp.
I have data for 10 people every 10 minutes. I am a student and it is for my department. We have a big display in the common area and the visua... | g65518 | [
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<p>In R, when I have a (generalized) linear model (<code>lm</code>, <code>glm</code>, <code>gls</code>, <code>glmm</code>, ...), how can I test the coefficient (regression slope) against any other value than 0? In the summary of the model, t-test results of the coefficient are automatically reported, but only for compa... | g65519 | [
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<p>I have collected data for 3 decades for 5 things. I want to see if there is a change in these five things over the period of three decades. For example if A was 20 out of 80 in decade1, 40 out of 120 in decade 2 and 50 out of 70 in decade 3. now i want to check if the change in A was statistically significant over ... | g65520 | [
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<p>I have some questions about the notations used in Section <em>9.2 Lack of Inherent Superiority of Any Classifier</em> in Duda, Hart and Stork's <em><a href="http://books.google.com/books?id=YoxQAAAAMAAJ&q=duda+pattern+classification&dq=duda+pattern+classification&hl=en&sa=X&ei=3Jo2T4eMM8bZ0QHm4pS... | g24119 | [
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<p>I have recordings of intensities of two fluorescent antibodies on a 2d image $2^{10} \times 2^{10}$ pixels in size, giving me $2^{20}$ pairs of numbers. </p>
<p>What is the best way to find the best straight line approximation in the plane, in the sense that the sum of squares of Euclidean distances from the points... | g65521 | [
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<p>So first, sorry if I use non-standard vocabulary, since I am not an expert. Please feel free to correct.</p>
<p>I would like to know if a set of genes in a patient cohort are mutated by a mutually exclusive manner. While one can observe this easily by eye, it is unclear to me how to test this in a statistical rigor... | g65522 | [
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<p>I realize this error message has been posted before, but the solutions previously provided does not work for me, so here goes:</p>
<p>I am working with a data.frame, which looks like this:</p>
<pre><code>> str(jiz)
'data.frame': 306256 obs. of 24 variables:
$ supremacy : Factor w/ 6 levels "-1.5","-1","... | g65523 | [
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<p>I have made a call for the KS-test function on python to compare 12 features, to see which ones help more to discriminate one population group from another (I am showing only two in the example: size and duration), and I am kind of lost in explaining the output. Here is my code:</p>
<pre><code>from scipy.stats impo... | g24122 | [
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<p>I am trying to fit GLMM's to my data using the glmer function available in R's lme4 package. The data is available at: <a href="https://onedrive.live.com/redir?resid=1B727FC7180E87DF%21118" rel="nofollow">https://onedrive.live.com/redir?resid=1B727FC7180E87DF%21118</a></p>
<p>I keep getting warning messages. Can an... | g65524 | [
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<p>Imagine the following type of dataset: I have a dependent variable Y, two independent variables X and Z, and a variable that can separate the dataset in two smaller datasets.</p>
<p><img src="http://i.stack.imgur.com/Tp2Qt.jpg" alt="enter image description here"></p>
<p>I estimated 2 identical OLS regressions for ... | g65525 | [
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<p>According to the literature, for temporal correlation modeling the trend should be removed from the time-series data. We choose differencing for removing the trend.</p>
<p>I would like to know:</p>
<p>When we perform the differencing the data completely change and subsequently the predictions will be changed.
How... | g4788 | [
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<p>I've recently run into an interesting and rather odd problem with cross validating a multiclass SVM that I can't figure out. Basically, I have a timeseries to predict and have created a dataset of what I believe are relevant predictors (also timeseries). I've done some preprocessing (reduced the example size of the ... | g65526 | [
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<p>I have a data set consisting of a number of variables: all are Boolean true/false type. Can I simply count the R correlation coefficient between two variables substituting 0 and 1 to get correlation matrix?</p> | g49727 | [
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<p>Suppose you are analyzing a huge data set at the tune of billions of observations per day, where each observation has a couple thousand sparse and possibly redundant numerical and categorial variables. Let's say there is one regression problem, one unbalanced binary classification problem, and one task of "find out ... | g24126 | [
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<p>I'm analysing data with a nested structure with the lmer-function of the Lme4 package in R. I'm interested in the estimation of the confidence intervals of the random effects (is the score of class1 higher than class2 nested within school A).</p>
<p>I found very small standard errors using ranef(mod, postVar=TRUE),... | g65527 | [
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<p>My dataset is made of a label, $y_{t}$, which is the dependent variable, and about 20 columns of independent numeric variables, $X_{t}$, $t=1,2,...,T$.</p>
<p>These samples are time series and my goal is to classify $y_{t}$ according to $X_{t}$.</p>
<p>The dependent variable can get just two labels: "$0$" or "$1$"... | g65528 | [
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<p>I have a conceptual problem to understand the standard error of the ratio of two random variables after error propagation.</p>
<p>Let $X$ and $Y$ be two random variables with means $\bar x$ and $\bar y$ and standard errors $se_x = \frac{\sigma_x}{\sqrt{m}}$ and $se_y = \frac{\sigma_y}{\sqrt{n}}$, where $m$ and $n$ ... | g65529 | [
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<p>So I have data elements such as rent price, late payments, unit type and location. I haven't done statistical analysis since my university time where I majored in industrial engineering 2 years ago</p>
<p>anyways my approach is to look for different metrics to look at such as avg rent price, occupancy rate (look a... | g65530 | [
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<p>I know the interval for a unconditional forecast. However, my question is:</p>
<p>How do you estimate a forecast interval for a conditional forecast?</p>
<p>Can anyone give me a hint?</p> | g65531 | [
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<p>I have a data set that includes a primary dichotomous independent variable (e.g., smoking), a primary dichotomous dependent variable (e.g., chronic back pain), and several covariates (e.g., diagnosis of several mental disorders, age, sex). I have calculated propensity scores for smoking using the covariates of inter... | g65532 | [
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<p>I'm somewhat new the world of statistics, or at least it has been years since I last used it and basically the only program I know generally how to work with is SPSS. However, for my Master thesis I need to analyse a dataset I made, so there's no escaping it now. </p>
<p>My research is about whether there is a diff... | g24128 | [
-0.0026864223182201385,
-0.039196986705064774,
-0.021059231832623482,
-0.05401405692100525,
0.012587944976985455,
-0.003932231571525335,
0.054912544786930084,
0.0632479190826416,
0.005302988458424807,
-0.030349452048540115,
0.031648632138967514,
0.020136792212724686,
0.02558256685733795,
-... |
<p>This paper discusses some of the dangers of using stepwise variable selection procedures:</p>
<p><a href="http://www.auburn.edu/~tds0009/Articles/Whittingham%20et%20al.%202006.pdf" rel="nofollow">http://www.auburn.edu/~tds0009/Articles/Whittingham%20et%20al.%202006.pdf</a></p>
<p>I'm struggling to understand Figur... | g24130 | [
0.07879400253295898,
-0.05198800563812256,
-0.008666726760566235,
-0.033122945576906204,
0.06518393009901047,
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0.04713936150074005,
0.022661825641989708,
-0.03629016876220703,
-0.005469298921525478,
-0.0161074697971344,
-0.02347002737224102,
0.013930295594036579,
0.0... |
<p>In COX PH, how can I know the model, I have, is robust? AIC and -2LL will only tell me relatively the goodness of model.
Also, is there a way to compute (in R) the relative log hazard scale as opposed to cumulative? </p> | g65533 | [
-0.007619153708219528,
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0.013325363397598267,
0.05048888921737671,
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0.028709325939416885,
0.016993483528494835,
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0.003883873112499714,
0.0010544477263465524,
0.06259673088788986,
0.11271155625581741,
-0... |
<p>I am running a simulation. One of my parameters is sampled from a normal distribution. I would like to perform a sensitivity analysis using a right skewed distribution.</p>
<p>This is what I had hoped to do: specify a log normal distribution, with a leftward translation so that it has the same cumulative density be... | g4436 | [
-0.018392402678728104,
-0.0461093932390213,
-0.005987969227135181,
-0.014207044616341591,
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0.01231315080076456,
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0.017259128391742706,
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0.015193927101790905,
-0.0354112833738327,
0.011994029395282269,
-0.014389771036803722,
... |
<p>Consider the following data and the code</p>
<pre><code>% The data
x = [4 4.5 5 5.5 6 6.5];
y1 = [0.000159334114311,0.000184477307337,0.002931979623674,...
0.004321711975947,0.006269020390557,0.012537205790269];
y2 = [0.000160708687146,0.000186102543697,0.002956862489638,...
0.004356837209873,0.006325918... | g65534 | [
0.05891147628426552,
-0.058823008090257645,
0.007625410798937082,
-0.0037998680491000414,
0.031098855659365654,
0.01083048153668642,
0.05202748626470566,
0.028200337663292885,
-0.048387523740530014,
-0.018997499719262123,
-0.03892016410827637,
0.05469749867916107,
0.03219624608755112,
-0.0... |
<p>I have been reading about maximum likelihood estimation and maximum a posteriori estimation and so far I have met concrete examples only with maximum likelihood estimation. I have found some abstract examples of maximum a posteriori estimation, but nothing concrete yet with numbers on it :S</p>
<p>It can be very ov... | g65535 | [
0.05860324576497078,
-0.007330437656491995,
0.01207981538027525,
-0.01961655355989933,
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-0.04970058053731918,
0.03257441148161888,
-0.04021477326750755,
0.04773739352822304,
-0.0075949933379888535,
-0.01379583403468132,
0.02448107860982418,
0.0483... |
<p>I tried to create a neural network for regression. In order to test the concept, I created a dataset the following way:</p>
<pre><code>x1 = random('Normal',0,5,500,1);
x2 = random('Normal',0,5,500,1);
y = x1 + 2*x2;
X = [x1 x2];
</code></pre>
<p>So x1 and x2 are vectors of random numbers with mean value 0 and stan... | g65536 | [
0.006298375781625509,
0.0057958513498306274,
-0.01446374598890543,
0.013086791150271893,
0.022413598373532295,
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0.12011328339576721,
0.08473960310220718,
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-0.019849885255098343,
-0.018371282145380974,
0.0853210911154747,
-0.002402547048404813,
0.02... |
<p>Basic problem but I can't seem to figure out how to think about this:</p>
<p>In a simple OLS problem the estimate of parameter $\beta$ is $\beta^*=(X'X)^{-1}X'Y$.</p>
<p>Then, the standard error of $\beta^*$ is $s (X'X)_{jj}^{-1/2}$.</p>
<p>But $s^2$ is uncertain. It has a probability distribution. Let's assume ... | g24142 | [
0.013644467107951641,
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-0.01256049145013094,
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0.01884293556213379,
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0.005279510747641325,
0.012494686059653759,
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0.01210749614983797,
0.015060065314173698,
0.052006348967552185,
-0.0038312976248562336,
... |
<p>Can anybody recommend me a good book on Computational Statistics? I am new to this subject so I am not sure how to be more specific.</p> | g24148 | [
0.054825309664011,
0.07222411036491394,
0.027138132601976395,
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0.011279270052909851,
0.02786300890147686,
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0.0010100569343194366,
0.006077730096876621,
0.03560518100857735,
0.06133238598704338,
-0.01527... |
<p>This is a very basic question, but I haven't been able to get an answer with my google-fu.</p>
<p>In the following sentences:</p>
<blockquote>
<p>We regress W on Z </p>
<p>We performed a regression of W on Z</p>
</blockquote>
<p>I'm unsure what <strong>of</strong> and <strong>on</strong> denote. Do I read ... | g24703 | [
0.03754713386297226,
-0.0030210295226424932,
-0.026479527354240417,
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0.08508875221014023,
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0.032519057393074036,
0.053253307938575745,
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-0.05086608976125717,
-0.01392152439802885,
0.0865287259221077,
0.03808851167559624,
0.... |
<p>I now have a problem with effect size of LMM. Someone insisted that I should have effect sizes after p values. I then thought that I can use 'estimate' in the output of pairwise comparison using lsmeans function. He is not convinced by using estimate and suggested me to use cohen's d. Then I look at the calculation ... | g49511 | [
-0.010227339342236519,
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0.018089067190885544,
-0.08863998204469681,
0.0012333340710029006,
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0.029935678467154503,
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-0.03165096417069435,
-0.02141408808529377,
0.027921270579099655,
0.02707027830183506,
0... |
<p>I have 34 input random variables and one output random variable, named <code>R</code>.</p>
<p>From 33 input random variables and some dataset I determined the best predictive regression model.</p>
<p>Based on this model I can predict <code>R</code> from any values of the input random variables.</p>
<p>I also dete... | g65537 | [
-0.013523165136575699,
-0.0763058140873909,
-0.005005599465221167,
-0.01168049219995737,
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-0.0041039856150746346,
-0.01420620083808899,
0.035829681903123856,
-0.08088398724794388,
-0.028652064502239227,
-0.02984219789505005,
0.03990562632679939,
0.02305038645863533,
0... |
<p>I have a linear regression problem $$Ax=b$$ My initial approach that helped to solve some of my questions was using <strong>SVD</strong> and obtaining the chi-square and some other values that I am interested but it is breaking down for some cases for instance if my regression problem is as following :</p>
<pre><co... | g24150 | [
0.04682719707489014,
-0.040992721915245056,
0.0027444332372397184,
-0.008967842906713486,
0.0260938573628664,
-0.014905080199241638,
0.03734323009848595,
0.04682505875825882,
-0.007845408283174038,
-0.012709848582744598,
0.001662005903199315,
0.0317845419049263,
0.04657734930515289,
0.0493... |
<p>For example: if my dataset contains (A, B), but does not contain (B, A). Then the algorithm may generate the rule A -> B, but will not generate the rule B -> A.</p>
<p>Is there an association rules algorithm, or variation of an algorithm, that respects the order of items in this manner?</p> | g65538 | [
0.05565726011991501,
0.034887488931417465,
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0.014847863465547562,
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-0.026539558544754982,
0.0401943139731884,
-0.04594290256500244,
-0.0335499532520771,
0.02156493254005909,
-0.01971837691962719,
0.010456058196723461,
0.0094... |
<p>What is the standard notation for specifying nested factors, for example, if I am estimating a parameter $\large{\beta{{_\text{site}}_i}}$ for the effect of $i=1\ldots m$ sites, and $\large{\beta{{_\text{tr}}_j}}$ for $j=1\ldots n$ treatments, assuming that there are no treatments that occur at each site (except the... | g44167 | [
-0.008311263285577297,
-0.026745237410068512,
-0.03252215310931206,
-0.05006451532244682,
0.04483848065137863,
-0.053111035376787186,
0.05992557108402252,
0.08568671345710754,
-0.0026454951148480177,
-0.0025753944646567106,
-0.04287049546837807,
0.02661115676164627,
0.053918659687042236,
0... |
<p>I'm trying to analyze a pre/post study with 4 treatment groups. The Dependent Variable, <strong>Speed</strong>, measures how quickly a person's facial expression reaches peak intensity; this measure is normally distributed after log10 transformation. Another variable, <strong>Intensity</strong> of emotional expres... | g24156 | [
0.011933231726288795,
-0.08135265856981277,
-0.02568862959742546,
-0.048831675201654434,
-0.02352331578731537,
-0.023874999955296516,
0.06932367384433746,
0.04093091934919357,
-0.03856619819998741,
0.010286495089530945,
-0.011314908042550087,
-0.03542729839682579,
0.014983666129410267,
-0.... |
<p>I was tutoring a Stat student taking a probability course and I came across a problem dealing with variance of exponential that has left me confused.</p>
<p>$X \sim \mathrm{Exp}(\mathrm{rate}=\lambda)$ so $E(X)=1/\lambda$ and $\newcommand{\Var}{\mathrm{Var}}\Var(X)=1/\lambda^2$</p>
<p>Customers enter a store at a ... | g24157 | [
0.01909993402659893,
0.013328242115676403,
-0.016703614965081215,
-0.023670848459005356,
0.02835896424949169,
0.010516057722270489,
0.018231775611639023,
-0.05049732327461243,
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0.014973645098507404,
-0.022566113620996475,
0.03800605237483978,
0.03093191236257553,
0.012... |
<p>I am working with a dataset containing data from 15 different surveys. The surveys were presented all as one battery to participants, with questions from all surveys essentially placed into a pool and then presented to participants at one of 30+ 'random' assortments. Most of these surveys measure the DVs in which we... | g65539 | [
0.01582508720457554,
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-0.0008043517591431737,
-0.030892353504896164,
0.028615552932024002,
0.01893535442650318,
-0.019389044493436813,
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-0.0017655094852671027,
0.03187860548496246,
0.05882025510072708,
-0.037259720265865326,
0.024624088779091835... |
<p>I am using chi squared for feature selection in text classification.</p>
<p>However when I compute it I sometime have very big values. Like 100, 1000 or even 20000.</p>
<p>Is this normal ?</p>
<p>I wonder because I read that if the Chi Squared score equals 10.83 then the p-value is 0.01.</p>
<p>So we know at 99.... | g65540 | [
-0.03330808877944946,
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0.004025282803922892,
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0.04559949040412903,
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0.07525613158941269,
0.05690871179103851,
-0.0313141755759716,
-0.007416143547743559,
-0.04250430315732956,
0.05693410709500313,
0.033860113471746445,
0.022489... |
<p>I'm trying to make sense of a question which uses a zero-inflated poisson model given by:</p>
<p>$$
f(x; \lambda,\omega) = \begin{cases} \omega + (1-\omega)e^{-\lambda} &\mbox{if } x = 0 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (1) \\
\frac{(1-\omega)e^{-\lambda}\lambda^x}{x!} & \mbox{if } x = 1,2,3,\dots... | g65541 | [
-0.018991200253367424,
0.0006028025527484715,
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0.04178323224186897,
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0.048620663583278656,
0.04798710346221924,
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-0.04751533269882202,
-0.06915682554244995,
0.028134657070040703,
0.05914132297039032,
0.000... |
<p>I recently received a review of a paper from a Bayesian Statistics Journal. The Associate Editor wrote this mini-review (quoted below in full).</p>
<blockquote>
<p>The paper is talking about Bayesian modeling of DNA sequences.
However, the model uncertainty is not taken into account in Bayesian
inference; the... | g24163 | [
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0.005291794426739216,
0.011300741694867611,
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0.007364301010966301,
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0.04434884339570999,
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0.015843642875552177,
0.015581285580992699,
-0.01924019493162632,
0.043642546981573105,
-0... |
<p>I'm looking for an implementation of FNN (or better yet, a SOFNN as described by <a href="http://www.neural-forecasting-competition.com/.../43-NN3_kuremoto-resubmission%20only%20documentation.pdf" rel="nofollow">Forecasting Time Series by SOFNN with Reinforcement Learning</a>). Any language, though preference is J... | g30472 | [
0.016339905560016632,
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0.016903351992368698,
-0.0453476682305336,
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0.01409014593809843,
0.0216600950807333,
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-0.032064780592918396,
0.024225205183029175,
-0.005638372618705034,
0.029903922230005264,
0.031... |
<p>I'm a new R user and had just tried running friedman on non-normal and heteroscedastic data on seagrass. I am testing whether biomass is significantly different between sites across years. R (<code>friedman</code> function from <code>agricolae</code> package) returned result like this:</p>
<pre><code>Friedman's T... | g24165 | [
-0.006583570037037134,
0.00003125847069895826,
-0.013089822605252266,
-0.015964796766638756,
0.06751362234354019,
-0.04802340269088745,
0.061617810279130936,
0.03570696339011192,
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-0.02145310491323471,
0.007455719634890556,
0.02707247994840145,
0.04672970250248909,
0.0... |
<p>This question is prompted by <a href="http://stats.stackexchange.com/q/3556/159">discussion elsewhere</a>.</p>
<p>Variable kernels are often used in local regression. For example, loess is widely used and works well as a regression smoother, and is based on a kernel of variable width that adapts to data sparsity.</... | g65542 | [
0.07193686068058014,
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0.016600672155618668,
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-0.014823940582573414,
0.050800006836652756,
-0.004748024512082338,
0.029882246628403664,
... |
<p>trying to read a large dataset in R the console displayed the follwing errors:</p>
<pre><code>data<-read.csv("UserDailyStats.csv", sep=",", header=T, na.strings="-", stringsAsFactors=FALSE)
> data = data[complete.cases(data),]
> dataset<-data.frame(user_id=as.character(data[,1]),event_date= as.character... | g30502 | [
0.015035147778689861,
0.03701353818178177,
-0.031472425907850266,
-0.05852259323000908,
-0.027749378234148026,
-0.004878386855125427,
0.03992602974176407,
-0.021683456376194954,
-0.0369420200586319,
-0.023915058001875877,
0.04225689172744751,
-0.024750467389822006,
0.04895230755209923,
0.0... |
<p>In my data, the RT (gaze) of individuals (ID) is examined as a function of a visual conditions, the factor size (small, medium, large).
Base model:</p>
<pre><code>print(Base <- lmer(RT ~ Size + (1|ID), data=rt), cor=F)
</code></pre>
<p>Random effect:</p>
<pre><code>print(NoCor <- lmer(RT ~ Size + (0+Size|I... | g65543 | [
-0.004632449243217707,
-0.01738104782998562,
-0.007671669591218233,
-0.05451050028204918,
0.0035501576494425535,
0.015418692491948605,
0.06887588649988174,
0.029531551524996758,
-0.007756005506962538,
-0.04246455058455467,
0.004565802402794361,
0.03134676441550255,
0.06257489323616028,
0.0... |
<p>I have a great prediction yet I am unsure how to uncover how the results were generated?</p> | g65544 | [
0.03792791813611984,
0.020486051216721535,
-0.004372152499854565,
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0.03427431732416153,
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0.04103783518075943,
0.02838512510061264,
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-0.0905103012919426,
-0.05796798691153526,
-0.011636684648692608,
0.06684376299381256,
0.0191... |
<p>I have two questions about output of hierarchical clustering and improving the output.</p>
<p>I'm trying to learn more about performing hierarchical clustering in R so I started looking at a simple dataset I created of sushi rolls at a <a href="http://www2.beyondmenu.com/22361/hicksville/blue-fish-hicksville-11801.... | g733 | [
0.08235210180282593,
0.03149392828345299,
0.0012858735863119364,
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0.011091732420027256,
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0.01752428710460663,
0.05129365622997284,
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-0.02811933308839798,
0.014006965793669224,
0.029637876898050308,
0.08416463434696198,
0.03891144... |
<p>My name is Abhi and I trying to teach myself logistic regression by solving some of the problems available on the internet. I am using R and RStudio as the development environment</p>
<p><strong><em>Problem Statement</em></strong>
<br>
Given the age, sex, class(first,second,third), ticket_id for each passenger can ... | g65545 | [
-0.018323490396142006,
-0.10045420378446579,
0.020769082009792328,
0.024003757163882256,
0.03952813148498535,
0.037422019988298416,
0.08036162704229355,
0.018480192869901657,
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-0.01951112039387226,
-0.02532208524644375,
0.03318050876259804,
0.053617727011442184,
-0.018... |
<p>I found an equation that says the standard error of the sampling distribution of the mean is:</p>
<p>$$\sigma_{\bar{X}} = \sigma \cdot \sqrt{\frac{1}{n}-\frac{1}{N}}$$</p>
<p>And when the population size is very large, the factor $1/N$ is approximately equal to zero; and the standard deviation formula reduces to:<... | g24173 | [
0.005317057482898235,
0.0157390758395195,
-0.03752757981419563,
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0.029861824586987495,
0.008553534746170044,
0.044107116758823395,
0.03220625966787338,
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-0.024614958092570305,
-0.06482696533203125,
0.019282689318060875,
-0.008591463789343834,
0.000... |
<p>Let's say I have a dataset with 1000 observations in 10 variables, "A" through "J." I have 1000 responses/measures for each of the first 8 variables, through "H," but only the first 500 observations for "I" are not missing, and only the last 500 observations for "J" are not missing -- there are no observations for w... | g24175 | [
0.020813584327697754,
-0.019301502034068108,
-0.00009644762758398429,
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0.019934244453907013,
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0.060297541320323944,
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-0.0031886242795735598,
0.010195426642894745,
-0.010168943554162979,
0.036409635096788... |
<p>If given probability of $A$ is $a$ and probability of $B$ is $b$, how do I find min/max probability of intersection? Max value of intersection would be $\min(a,b)$, how do I find the min? </p> | g65546 | [
0.00917096808552742,
-0.026788631454110146,
0.005788156762719154,
0.039737291634082794,
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0.04651014879345894,
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-0.0253971666097641,
0.026299670338630676,
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0.0330684632062912,
0.0... |
<p>I'm trying estimate an autoregressive model with an exogenous variable. It's about the impact of changes in oil prices on the economy. I'm planning on regressing gdp growth rate on its own lagged values and lagged values of oil price.</p>
<p>I don't know from where to start. Here's what I think so far: </p>
<ol>... | g734 | [
0.03870145231485367,
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0.020969463512301445,
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0.07679948955774307,
0.022533483803272247,
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0.01111726276576519,
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0.07293407618999481,
0.05290941148996353,
0.02... |
<p>In the MATLAB stats tutorials there is a section called <em>"Fitting a More Complicated Distribution: A Mixture of Two Normals"</em>
<a href="http://www.mathworks.com/help/stats/examples/fitting-custom-univariate-distributions.html" rel="nofollow">http://www.mathworks.com/help/stats/examples/fitting-custom-univariat... | g65547 | [
-0.0013263896107673645,
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0.008656800724565983,
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0.034506671130657196,
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0.06092597544193268,
... |
<p>I'm dealing spectral data. I want to classify 2 classes using principle components analysis. My PCA was constructed using <code>prcomp(data, center=TRUE)</code> in R. It works. My questions are: </p>
<ol>
<li><p>When using unknown data (input) to predict a classification, should the data be centered before applying... | g65548 | [
0.05863725766539574,
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0.009405306540429592,
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0.026606226339936256,
0.053235869854688644,
0.0003019753785338253,
-... |
<ol>
<li><p>How to know the data points are linearly separable from an SVM hyperplane?</p></li>
<li><p>How to get the optimal classifier during iteration process?</p></li>
<li><p>How to calculate the complexity of the SVM model?</p></li>
</ol> | g24179 | [
0.032481443136930466,
0.04797684773802757,
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0.031250130385160446,
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0.02920839749276638,
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0.0048913294449448586,
0.028502535074949265,
0.04... |
<p>I have logs with the following information:</p>
<p>date-time username view action action_data</p>
<p>These logs are generated from a web-application which consists of several views where the users can perform a variety of actions which are logged (which elements they click, if they hover somewhere, switch views et... | g65549 | [
0.002400849713012576,
0.04559297487139702,
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0.07631610333919525,
... |
<p>I have a dataset where I extract the mean and the standard deviation, I want to generate a new synthetic dataset which is lognormal distributed based on the original dataset paramaters. Like a montecarlo simulation.</p>
<p>My problem is that I need that synthetic dataset is truncated, with the maximum and minimum v... | g35645 | [
-0.006941055878996849,
0.0006249931757338345,
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0.011354568414390087,
0.03518211841583252,
... |
<p>In particular, is the $n$th cumulant equivalent to the $n$th central moment (i.e. about the mean)?</p>
<p>There's little difference I can see between MGFs (moment generating) and CGFs (cumulant generating), apart from the former gives moments about the origin while the latter yields central moments.</p> | g65550 | [
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0.016932256519794464,
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0.042837582528591156,
... |
<p>I have two independent variables: "vaccination status" and "antibody titer assessment". Vaccination is coded as 0 and 1. The other variable is supposed to explain if the person has checked that whether the vaccination has increased his antibody titer sufficiently. The second variable has two states: yes or no.</p>
... | g24182 | [
0.03750644624233246,
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0... |
<p>I have noticed it is somewhat common for people to collect data, perform a statistical test (e.g., t-test) and then also look for possible "outliers" in the data. Then they remove the outliers and also perform the test on the filtered data. </p>
<p>If it is significant in both cases it is concluded that "the outlie... | g24183 | [
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0.021808482706546783,
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0.009243682958185673,
0.0... |
<p>I'm trying to find the optimal threshold point from a ROC curve. I have two main constraints : tpr >=80 and fpr <=60. I tried three main minimization functions :</p>
<pre><code>#where, tpr=True positive rate and fpr = false +ve rate
dis= math.sqrt(math.pow((1-arr[1]), 2) + math.pow((0-arr[0]), 2))
dis= math.po... | g65551 | [
0.015358596108853817,
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0.018685031682252884,
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0.044850803911685944,... |
<p>Just when I thought I'd had a grip on how to do an analysis of variance this particular data set had me startled: it's a collection of response times (in ms) to a linguistic input. To be precise, it's part of a reading time experiment, and I'm trying to see if there's a significant effect of two factors.</p>
<p>My ... | g38664 | [
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0.004806812386959791,
0.011895738542079926,
0.05408186838030815,
0.014523573219776154,
-0... |
<p>I would like to know how to calculate the standard deviation for a measurement value $x$ when there are two separate sources of uncertainty, 1 and 2, each with known standard deviation, $\sigma_1$ and $\sigma_2$.</p>
<p>I’ll give a couple of examples.</p>
<ul>
<li><p>I measure length with a ruler. Each measurement... | g65552 | [
0.014489537104964256,
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0.0004598619416356087,
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0.007693049497902393,
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0.05796929821372032,
... |
<p>Suppose we have N independently drawn samples from an unknown random variable $X$. What is the best way to estimate the expectation of $X$?</p>
<p>For simplicity, we can assume that $X$ only returns values between 0 and 1.</p>
<p>I know this might be a stupid question: the standard way to estimate the mean is just... | g65553 | [
0.0020532384514808655,
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0.024021346122026443,
-0.004023655783385038,
-0.01735494472086429... |
<p>I am fitting my data to <strong>Weibull</strong> distribution (I would like to <strong>prove</strong>, that they follow a <strong>power law</strong>).</p>
<p>According to <a href="http://en.wikipedia.org/wiki/Heavy-tailed_distribution" rel="nofollow">http://en.wikipedia.org/wiki/Heavy-tailed_distribution</a> (and s... | g65554 | [
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<p>I tried to use <code>mlogit</code> for discrete choice modeling, but I found that I cannot estimate a model for the alternative specific variables, which are defined only for one alternative--for example, in a dataset like below:</p>
<pre><code>Num Mode Ftp
1 Bus 0
1 Walk 0
1 Car 1.0
2 ... | g65555 | [
-0.0888378918170929,
0.009131008759140968,
0.004982137121260166,
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-0.02098512277007103,
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-0.010853170417249203,
0.10133442282676697,
0.0... |
<p>I’m working on a data set in order to evaluate the impact of water stress on Rils population.
The experimental design is split plot augmented design and it's as follows:</p>
<p>The first factor (stressed/not stressed) is in Whole plot and there are no replicates.</p>
<p>The second factor (genotypes) is in split p... | g29170 | [
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0.03633048012852669,
... |
<p>Recently I have performed an <strong>exploratory regression analysis</strong>, using <code>lavaan</code> R package and observed the following <em>output</em> with some <strong>warning messages</strong> in it. I have the following <strong>question</strong>: What is the <strong>potential negative impact</strong>, if a... | g65556 | [
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0.032168418169021606,
0.06855104118585587,... |
<p>I have a 2 way contigency table with variables $A=\{a_1,a_2\}$ and $B=\{b_1,b_2\}$. I have the observed cell frequencies $O_1=a_1b_1$, $O_2=a_1b_2$, $O_3=a_2b_1$ and $O_4=a_2b_2$. My null hypothesis is that $A$ and $B$ are independent variables</p>
<p>I am interested to evaluate what is the probability of observing... | g24190 | [
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0.007157596759498119,
0.029745040461421013,
0.001123399124480784,... |
<p>We have 7 classification models generated from 30 subsets sampled from the same data-set (via cross-validation). We would like to know if there are significant differences among the accuracy of the 7 models.</p>
<p>Apparently, in a comment from <a href="http://stats.stackexchange.com/questions/17208/usage-of-the-fr... | g65557 | [
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0.015394894406199455,
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0.01320017222315073,
0.023623721674084663,
0.01... |
<p>I have a table as</p>
<pre><code>Date Time Energy
1/1/2008 10:30 0.89
1/1/2008 11:30 0.76
</code></pre>
<p>and so on. The data is recorded for every half an hour.
I wish to decompose this time series in R.</p> | g65558 | [
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0.008987515233457088,
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0.008058168925344944,
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... |
<p>When the confidence interval of an odds ratio includes one, can the p-value be less than 0.05?</p>
<p>For example,</p>
<pre><code>odds ratio = 0.54 confidence interval ( 0.29 - 1.01 ) and
p value is 0.039.
</code></pre>
<p>In this situation can we consider the effect to be statistically significant or not?
Or ... | g65559 | [
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0.019567985087633133,
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0.005290544591844082,
-0.0... |
<p>I think my various questions on this site about spline and polynomial regression boil down to this:</p>
<p>I have many datasets to analyze where individuals grow over time and, depending on treatment group, either plateau out or decline. Reporting that the "shapes of the curves are significantly different" won't cu... | g39227 | [
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0.015145494602620602,
0.1282002478837967,
0.0... |
<p>After doing some reading about the binomial distribution I found this about lower and upper bound probabilities</p>
<p>We can get the <strong>lower tail probability</strong> of X as:
$$P(X \leq x)=P(X=0)+...+P(X=x)$$ </p>
<ul>
<li><strong>Stata:</strong> as <code>binomial(n,k,p)</code></li>
<li><strong>R:</strong>... | g42002 | [
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0.029459618031978607,
0.02755119651556015,
... |
<p>If the distribution of the periods between an extreme event to another is a power law (as for example can be the return period of extreme earthquakes or flooding), the existence of the mean value is subordinated to the value of the exponent of the power law. In the cases where the exponent don't allow the existence ... | g39228 | [
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0.02383413165807724,
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-0.02... |
<p>I have a dilemma regarding p -value.</p>
<p>The idea is that a p value results from a comparison between a test statistic and control group such that the null hypothesis is assumed and based on this comparative score, p, we can determine the strength of the assumption that the observed results were by chance, or de... | g65560 | [
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-0.05763259530067444,
0.001194686978124082,
0.01205915492027998,
0.02986711822450161,
0.0... |
<p>I have a sample of data, and I want to know weather it is Gaussian-distributed or not. The mean of my data is not zero. </p>
<p>To check weather I'm using the K-S test correct, I generated some Gaussian-distributed data and added some bias: </p>
<pre><code>data = stats.norm.rvs(size=10000) + 1
print stats.kstest(... | g65561 | [
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0.00749701913446188,
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0.011913029477000237,
0.08105993270874023,
0.0034472967963665724,
-0... |
<p>I am running experiments for a paper and am looking for an interesting book/website to understand properly how anova and ancova work. I have a good math background so I don't necessarily need a vulgarized explanation.</p>
<p>I'd also like to know how to determine when to use anova versus ancova.</p> | g65562 | [
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0.03647279366850853,
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0.009958137758076191,
0.03208286315202713,
0.033... |
<p>This question might sound simple, but in fact I am absolutely unsure whether it is allowed to use an LRT for model comparison when the error distributions differ. </p>
<p>For example, can I compare a model with a gaussian distribution with a gamma or a log-gamma model?</p> | g10858 | [
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<p>Suppose I am modeling the sales for multiple products for multiple stores. What is the difference between:
\begin{align}
\text{Sales} &= \beta_{0}(\text{Intercept × Store}) +\beta_{1}(\text{Intercept × Product}) \\
&\text{and} \\
\text{Sales} &= \beta_{0}(\text{Intercept × Store}\times\text{Product})
... | g35238 | [
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-0.027372805401682854,
0.014797624200582504,
-0.04002128168940544,
0.07217413187026978,
0.035275548696517944,
-0.033988773822784424,
-0.032319650053977966,
0.006184051278978586,
0.023042937740683556,
0.027246272191405296,
... |
<p>I do not understander how "thin" setting affects the number of samples in WinBUGS. Here is my case:</p>
<p>Case 1: In <code>Model --> Update... -> Update Tool</code>, I set <code>updates</code> 5000, <code>refresh</code> 100, <code>thin</code> 1, click <code>update</code>. In <code>Inference -> S... | g65563 | [
0.0394674651324749,
-0.02660047449171543,
-0.00803481787443161,
-0.03306135535240173,
0.03716295585036278,
-0.02744954638183117,
0.05278422310948372,
0.0009211368160322309,
-0.09437619149684906,
-0.038202155381441116,
-0.02059922367334366,
0.02656232938170433,
0.03218766674399376,
0.065452... |
<p>Can someone give a concise, layman's explanation of an "If-Then" rule (as in rule-based systems). I am finding this term used frequently without anyone really defining it properly.</p> | g24199 | [
0.08142261952161789,
0.09879904985427856,
-0.0009667723206803203,
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0.020298458635807037,
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-0.002618132857605815,
0.05438432842493057,
... |
<ol>
<li><p>When doing a multiple regression and testing for homoscedasticity
some people look at raw observations and others the residuals. Which
is correct?</p></li>
<li><p>Do you use raw data or residuals to test linearity?</p></li>
<li><p>Do you test the homoscedasticity for each IV against the DV or do
you put all... | g65564 | [
0.035074882209300995,
-0.04697341099381447,
-0.0001592378393979743,
0.017663899809122086,
-0.02797853946685791,
-0.035179294645786285,
-0.010589554905891418,
0.045379456132650375,
-0.05938839912414551,
-0.03798762708902359,
0.015271060168743134,
0.010816539637744427,
-0.02577027678489685,
... |
<p>Could anyone suggest a statistical technique for comparing two distributions, where the numbers in each distribution are proportions?</p>
<p>I have two distributions, each of which reports the proportion of entities in one of 12 classes. Unfortunately, I don't know much about the sample size for one of these distri... | g65565 | [
0.028541268780827522,
-0.02986971102654934,
0.012736355885863304,
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0.004004914313554764,
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0.01569867879152298,
0.014486405998468399,
-0.012720861472189426,
0.09559151530265808,
-0.042340438812971115,
0.05981928110122681,
0.0... |
<p>I am reading this paper on <a href="http://uai.sis.pitt.edu/papers/11/p736-wilson.pdf" rel="nofollow">Generalised Wishart Process (GWP)</a>. It is about modelling covariance matrix of D - dimensional gaussian processes (GP) as GWP. I fail to understand interpretation of "degrees of freedom" $\nu$ for a GP.</p>
<p>T... | g65566 | [
0.00488874688744545,
-0.025050077587366104,
-0.019329847767949104,
-0.04871148243546486,
0.027080271393060684,
0.02644547075033188,
0.08077752590179443,
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-0.02975507453083992,
-0.014109116047620773,
0.024838240817189217,
0.0401318222284317,
-0.0... |
<p>I've got a model that looks like this:</p>
<p>$$Y_{ig} = \left(\beta_{everyone} + \beta_g\right)X_{ig} + Z_{ig}'\gamma + \epsilon_{ig}$$</p>
<p>in R, this is </p>
<pre><code>library(lme4)
example = lmer(Y~ X + Z + (0 + X|g))
</code></pre>
<p>I want a conditional estimated distribution of $Y|G=g,X=x,Z=z$</p>
<p>... | g44223 | [
-0.020618850365281105,
-0.07875525206327438,
-0.015102664940059185,
-0.039324164390563965,
0.0011484331917017698,
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0.0168460700660944,
0.000238978915149346,
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-0.05516358092427254,
0.02532901242375374,
0.005005513783544302,
0.01537531241774559,
0.02... |
<p>In time series forecasting using various models like AR,MA,ARMA, etc, we usually focus on the modeling of the data in the change of time. But when we have 2 time series that <strong>Pearson correlation coefficient</strong> show they are highly correlated, is it possible to model their dependency and forecast values ... | g65567 | [
0.02567632496356964,
-0.06585600227117538,
0.022821899503469467,
-0.021761072799563408,
-0.026745762676000595,
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-0.02904743142426014,
-0.0026047141291201115,
0.014734448865056038,
-0.010180898010730743,
0.08126705139875... |
<p>I have encountered many peculiarities/misunderstandings of Vowpal Wabbit when trying to do online multiple-pass learning.</p>
<p>Specifically, I need to solve a <a href="http://en.wikipedia.org/wiki/Tikhonov_regularization" rel="nofollow">Ridge Linear regression</a> problem, with <code>N=4e6</code> points and a tot... | g10860 | [
-0.025734907016158104,
-0.032253578305244446,
-0.008575995452702045,
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0.03694737330079079,
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0.07735276222229004,
0.02797086536884308,
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-0.02708221599459648,
-0.019366100430488586,
0.0051385206170380116,
0.05925692990422249,
0.03... |
<p>The test of Kolmogorov-Smirnov (K-S) is a traditional test of normality, although Shapiro-Wilk test (S-W) is applied more frequently than K-S (<a href="http://www.grupogen.com.br/ch/prod/8045/3677/3438/bioestatistica-teorica-e-computacional.aspx" rel="nofollow">Arango, 2012</a>). </p>
<p>I am not an expert in stati... | g65568 | [
0.02284064143896103,
0.019691448658704758,
0.0046175760217010975,
0.05467655882239342,
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0.017666997388005257,
0.04619898647069931,
0.048968054354190826,
0.04164951294660568,
0.0735699... |
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