question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have two basic models $M_1$ and $M_2$. They each have a likelihood function;
$L_{M_1} = f(\mathbf{X}|\mathbf{\theta_1})$ and $L_{M_2} = f(\mathbf{X}|\mathbf{\theta_2})$ (here $\mathbf{X}$ is the data set, and $\mathbf{\theta_i}$ are the parameters for the model). The models are nested since model $M_1$ parameter'... | g63042 | [
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<p>Let's say I want to perform an AB-Test with the following properties:</p>
<ul>
<li>We assign unique visitors to each group, not the requests (so each trial corresponds to a unique visitor as long as e.g. the cookie is not deleted)</li>
<li>We want to measure "items viewed" per unique visitor (side note)</li>
</ul>
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<p>Disclaimer : I am not a math/stats major. Please pardon & feel free to correct non-standard words I may use.</p>
<p>Following is an arrangement I currently have with me,</p>
<p>I have a matrix r x c where value of each cell is a binary 0/1. This r x c matrix is "connected" to further r matrices. Such a connect... | g63043 | [
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<p>I have timeseries like this:</p>
<p><img src="http://i.stack.imgur.com/2oNmT.png" alt="enter image description here"></p>
<p>as you can see there are changes regarding the amplitude. Is there a test to check this kind of changes? </p>
<p>Important annotations:</p>
<ol>
<li>I do not know if the series have change... | g609 | [
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<p>I am using a generalized linear model in SPSS to look at the differences in average number of caterpillars (non-normal, using Tweedie distribution) on 16 different species of plants. </p>
<p>I want to run multiple comparisons but I'm not sure if I should use a Sidak or Bonferroni correction test. What is the differ... | g20511 | [
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<p>I have count data (demand/offer analysis with counting number of customers, depending on - possibly - many factors). I tried a linear regression with normal errors, but my QQ-plot is not really good. I tried a log transformation of the answer: once again, bad QQ-plot.</p>
<p>So now, I'm trying a regression with Poi... | g39703 | [
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<p>I draw a random vector of dimensionality $k$, each dichotomous element of which taking on a value in $\{0,1\}$. The probability that any element will be $1$ is captured in the $k$-dimensional parameter vector $\bf{p}$, the elements of which are in $[0,1]$ and sum to $1$ (or are normalized as such prior to use). A sp... | g63044 | [
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<p>I have some data that measures how a substance decays over time. At each time point I have 4 measurements. At time points where there is a lot of substance I use the standard error for error bars and this seems standard practice. However, when the amount of substance nears zero and I have a lot of variability in the... | g219 | [
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<p>I have a few bins of data. From each bin(which has a few thousand data points), I can compute the total number of data points, the mean of the data points, etc.. I can probably compute any/most statistical entities(mean, median, etc.) of each bin(computationally easy). However, I want to find the 95th percentile of ... | g63045 | [
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<p>I have data that consists of 10 repetitions of a measurement per person, for all repetitions there is one control value and one test value (after conditioning). This data will be reproduced in multiple people.</p>
<p>I am now thinking how to introduce the intra-individual variance into the statistical test. Without... | g63046 | [
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<p>I am considering two types of systems - which might have more appropriate names:</p>
<p><strong>Recommender systems:</strong> These recommender systems are based on collaborative filtering methods, both model-based and memory-based. They take a partially filled user/item matrix of ratings of items by users, and try... | g8262 | [
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<p>Simple question: How to specify a lognormal distribution in the GLM family argument in R?
I could not find how this can be achieved. Why is lognormal (or exponential) not an option in the family argument?</p>
<p>Somewhere in the R-Archives I read that one simply has to use the log-link for the family set to gaussia... | g37791 | [
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<p>I would like to know the difference between below mentioned stopping criteria used in various gradient descent algorithm</p>
<ol>
<li>$\frac{Prev\_fun\_value - curr\_fun\_value}{Pre\_fun\_value} \le tol$</li>
<li>$Prev\_fun\_value - curr\_fun\_value \le tol*max(1,Prev\_fun\_value)$</li>
</ol>
<p>where $Prev\_fun\_... | g20517 | [
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<p>I note with interest an article which has been suggested to me over here:
<a href="http://blog.stata.com/tag/poisson-regression/" rel="nofollow">http://blog.stata.com/tag/poisson-regression/</a></p>
<p>I have the problems outlined in this blog - namely zeros (in the independent variables).
The article suggests the ... | g253 | [
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<p>This is a biological experiments question.
I compare the percentage (%; relative frequency) of mutant cells showing phenotype against wild type cell (wt) with repeated times, for example, three independent trials.</p>
<p>I: wt (0.02 = 2 out of 100) vs mutant (0.50 = 50 out 100)
II: wt (0.027 = 4 out 150) mutant (0... | g38423 | [
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<p>What analysis should I perform if I am trying to find if there is an association between socio-demographic variables and my dependent variables. All my variables are categorical nominal.</p>
<p>Also I am trying to see if there is a change in my dependent variables in my control group at baseline and follow up. Agai... | g49887 | [
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<p>I'm wondering what the best ways to compare (possibly ranked) lists when we know what the true ranking is and also the variable that decides the ranking. </p>
<p>Say this is the top 10 of a certain list, we know the ranking, and also the variable from which the ranking is obtained (Votes).</p>
<p><strong>True Rank... | g20523 | [
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<p>I'm using JAGS to run a meta-analysis and I've run into an issue. I have calculated log-response ratios and errors for about 177 studies, where studies fall into one of 8 groups. I'm interested in estimating an overall effect as well as a effects for each group. I've discovered that if I use the model</p>
<pre><cod... | g63047 | [
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<p>It seems that statisticians are usually only interested in statistical power. In other words, they are interested in the probability of correctly rejecting the null hypothesis. </p>
<ul>
<li>What if we are interested in the probability of correctly not rejecting the null hypothesis?</li>
<li>Would we change the hyp... | g63048 | [
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<p>Last year, I read a blog post from <a href="http://anyall.org/">Brendan O'Connor</a> entitled <a href="http://anyall.org/blog/2008/12/statistics-vs-machine-learning-fight/">"Statistics vs. Machine Learning, fight!"</a> that discussed some of the differences between the two fields. <a href="http://andrewgelman.com/2... | g49750 | [
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<p>i'm having a hard time finding the right model for my data. The study is about the effect of a drug (more precise: the effect of the dose of a drug) and the time on the subject (rat). So i got the following variables:</p>
<ul>
<li>Dependent Variable: Relative Change</li>
<li>Independent Variables: Dose (Levels: 1, ... | g39734 | [
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<p>I have various object vectors (PC1, PC2, PC3) representing objects ater normalisation and PCA. I also have 'axis' vectors (PC1, PC2, PC3) representing the axis that the objects were originally placed along e.g. hot/cold, like/dislike. What I would like to know is if I do a projection of the object vectors on to the ... | g39724 | [
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<p>Is there any function in R for doing variable selection (backward elimination) in a multiple logistic regression using restricted cubic splines like <strong>mvrs</strong> procedure for STATA?</p> | g8321 | [
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<p>I have been asked to look at some spatial data, which I have assumed is multi-normally distributed in 3 dimensions (and to a reasonable approximation this appears to be true). Actually, all I've been asked to do is provide a table so that someone can specify a probability and I tell them how many standard deviations... | g49073 | [
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<p>We have longitudinal data on children(n<20) in which we measure different quantities A,B,C,D (like distance walked, time spent in school etc.). These are all continuous variables. We measure these variables daily and we have been measuring them for more than one and half years. </p>
<p>Now, based on these varia... | g63049 | [
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<p>I have multiple GEE models predicting learning scores from the interactions of psychophysiological data of subjects, e.g. features of Electroencephalograph (EEG), respiration, etc., in a 2 condition design.</p>
<p>Thus for example one model is specified (in SPSS syntax) as follows (covariates are EEG delta power, d... | g63050 | [
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<p>Given interval censored survival times, how do I perform an interval censored Cox PH model in <code>R</code>? An rseek search turns up the package <code>intcox</code>, which no longer exists in the <code>R</code> repository. I'm almost positive the <code>coxph</code> function in the <code>survival</code> package can... | g41665 | [
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<p>"discriminant function" and "classification function" are two terms used in literature to denote a a function that maps a feature vector into a discrete class variable.</p>
<p>I presume "discriminant function" has it's origin in statistics and "classification function" in machine learning. Is there any reason these... | g63051 | [
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<p>I am working to build a model using logistic regression. There is one variable which has strong predictive power. But based on business rule, I cannot include this variable in the model. On the other hand, there are some variables which are insignificant in the model. But from business decision, they are added in t... | g63052 | [
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<p>I am wondering whether SVM based recursive feature elimination (Guyon et al., 2000) would be considered a filter or a wrapper method.</p>
<p>On the one hand, it "wraps" around an SVM to get the lowest-weight features.
On the other hand, the trained model is never applied to any test set.</p>
<p>What do you think?<... | g20530 | [
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<p>I have some time-series data that I wish to test to see if a certain factor has an effect. There are few samples per time step (10 on average), but the whole time-series has 306 samples. When divided into groups based upon a factor the result is non-normal and non homogeneous. I wish to test the effect of the factor... | g63053 | [
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0.011925428174436092,
0.014708283357322216,
0.02339266985654831,
-0.021950284019112587,... |
<p>I would like to conduct a meta-analysis in R of studies using a pre-post treatment design. In every individual study 4 different subgroups of patients have undergone a pharmacological treatment and their symptoms are measured on a continuous scale. For every study mean and sd of the effect size (cohens d) for the tr... | g37527 | [
-0.048720404505729675,
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... |
<p>I'm on the stage of experiment design of some biomedical time-course study. Let's say we will have 2 groups of subjects - case and control. The total number of subjects is limited (for example, 30), and we need to decide how it's better to split subjects between case and control. One way is to have balanced dataset ... | g63054 | [
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0.08564836531877518,
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0.018361104652285576,... |
<p>I read that OLS underestimates variance when residuals are autocorrelated. I see why autocorrelation would be a problem in time series analysis, in the sense that the coefficient are not efficient because we're not including all the potential predictors. But is there a mathematical problem as well?</p>
<p>For examp... | g63055 | [
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0.061426129192113876... |
<p>I have two different sets $(n_1=47$, $n_2=23)$ obtained under different conditions. I fit two different functions $(\text{Fu}_1$, $\text{Fu}_2)$ in MATLAB. $\text{Fu}_1$ was fit using the first data set, and $\text{Fu}_2$ was fit using the second data set.</p>
<p>$\text{Fu}_1(x,y) = A_1 + B_1x + B_2y$<br>
and<br>
... | g16329 | [
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-... |
<p>Does anyone have a clear explanation or reference as to why it is only important to transform the dependent variable and not necessarily the independent variables for improved skewness and kurtosis values?</p> | g28536 | [
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<p>I'm wondering whether a fixed-effects (logit) model fits the purpose of my study, and would like to get some feedback or ideas which other models could potentially be useful:</p>
<p>I have an unbalanced panel (daily observations, 3 months time period) with Twitter user data. Among the independent variables are</p>
... | g26196 | [
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<p>I believe some time series data I am looking at shows seasonality according to general elections (UK, so this can be 4 or 5 years). How do I remove this effect in R?</p> | g63056 | [
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<p>I'm trying to understand what is SVM regression. It's used for classification or regression?
Can someone give an intuitive understanding of it?</p> | g16330 | [
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<p>I'm trying to project a point into an existing PCOA (Principal Coordinates Analysis) space (in <code>R</code>). I am under the impression this must be possible, but I can't figure out how to go about it.</p>
<p>Here's how far I've gotten (a toy example):</p>
<pre><code>x <- c(1:10)
y <- c(10:1)
z <- c(rno... | g63057 | [
0.01319456659257412,
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0.002182794502004981,
0.04474033787846565,
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-0.... |
<p>Suppose we have the following classical normal linear regression model:</p>
<p>$$y_i = \beta_1 x_{1i} + \beta_2x_{2i} + \beta_3x_{3i} + e_i$$</p>
<p>where $e_{i} \sim iid.N(0, \sigma^2)$ for all $i = 1, 2, \cdots, n$ and $x_{1i} = 1$ for all $i = 1, 2, \cdots, n$.</p>
<p>I artificially generate data values for bo... | g20534 | [
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0.00059... |
<p>I have a somewhat trivial question regarding a mixed-effects model. The scenario is this: </p>
<ol>
<li>4 different treatments </li>
<li>3 different time points</li>
<li>All time points have the same number of samples in each treatment group but the 3rd time point has half of the overall points (<em>e.g.</em>, time... | g20535 | [
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<p>Let we've empirical data of two random variables X and Y.</p>
<p>We can estimate empirically the degree of correlation between the two random variables by observing their scatter diagram, for instance.</p>
<p>Since, <strong>Independent random-variables $\Rightarrow$ zero-correlation</strong></p>
<p>But <stron... | g63058 | [
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<p>I have categorical survey data on people's attitudes towards a certain policy area from 13 countries. The response variable is categorical, and includes 4 distinct answers that cannot be ordered. </p>
<p>I would like to build a multi-level random-intercept and random-slope multinomial model. The problem is, that th... | g20536 | [
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0... |
<p>Let us say I have a topic probability per document, for example:</p>
<pre><code>Doc1: Science:0.6, History:0.2, Politics:0.1, Sports:0.1
Doc2: Science:0.3, History:0.5, Politics:0.1, Sports:0.1
Doc3: Science:0.8, History:0.1, Politics:0.05, Sports:0.05
Doc4: Science:0.2, History:0.2, Politics:0.4, Sports:0.2
</code... | g63059 | [
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0.0103529... |
<p>I'm hoping someone can help straighten out a point of confusion for me. Say I want to test whether 2 sets of regression coefficients are significantly different from each other, with the following set up:</p>
<ul>
<li>$y_i = \alpha + \beta x_i + \epsilon_i$, with 5 independent variables.</li>
<li>2 groups, with rou... | g63060 | [
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<p>I have a bag of 10 coins; 1 of them has heads on both sides, while the rest are normal (have heads on one side and tails on the other). Each face of a coin is equally probable when tossed. You choose 1 of the coins from the bag at random and then flip it 100 times observing heads every time. What is the probabilit... | g63061 | [
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... |
<p>This is my first post on here, looking for some help. I am relatively new to analysis of temporal datasets. I have experience with R and developing linear models, so I am trying to figure out if the approach I am trying is appropriate with temporal data or if I need to do something different.</p>
<p>Data: Monthly m... | g23419 | [
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0.010724187828600407,
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0.04473661258816719,
0.017955977469682693,
0.03196434676647186,
0.0098... |
<p>I have a vector </p>
<p><code>x = c("E1","E2","E4","E4","E5","E6","E10","I1","I2","I4","I12")</code></p>
<p>I need to sort that in a way the output should be</p>
<p><code>x = c("E1","I1","E2","I2","E4","E4","I4","E5","E6","E10","I12")</code></p>
<p>but when I use <code>sort(x)</code> it gives</p>
<p><code>c("E1... | g20539 | [
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0.004902534652501345,
0.02904611825942993,
0.01522534154355526,
... |
<p>Given i.i.d. samples from a gaussian distribution $X_1,...,X_n \sim N(\mu,\sigma) $ and the M-estimator, $\mu_m = \underset{a}{\operatorname{argmin}} \sum\rho(|X_i-a|)$, what properties on $\rho$ are sufficient to guarantee $\mu_m \rightarrow \mu$ in probability? Is $\rho$ being strictly convex and strictly increas... | g63062 | [
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0.... |
<p>In <a href="http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.bsmsp/1200512173" rel="nofollow">James and Stein (1961)</a> the authors consider the following loss function for an estimator $\hat{\Sigma}$ of the covariance matrix $\Sigma$ of a multivariate normal distribution... | g63063 | [
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0.014130635187029839,
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0... |
<p>I am designing project which requires me to select a Control Group. One the business requirements stipulates that I select as small a sample size as possible for the Control Group so there will be more records for the Test Group. </p>
<p>I would like to select as small as possible a Control Grouo and still be conf... | g63064 | [
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<p>the question is trivial, but is there any statistical test (can be done in R) to show that the median is changing in a time-series?? For example, if you go to the following link, you would notice that, after the first few samples (6 or 7), the time series takes a sharp rise. I was wondering if there is a formal stat... | g63065 | [
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0.02121932990849018,
0.011859612539410591,
0.09527682512998581,
0.06520663946866989,
... |
<p>I know that this kind of discussion might be both a silly...very silly and a hot issue simultaneously...but I thought it would be nice to raise it : Which types of linear AND non-linear regression could be recommended when you have a small sample size (e.g. 50-70 records) and you want to predict a continuous outcome... | g43068 | [
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0.045790668576955795,
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0.038043733686208725,
... |
<p>Recently, I've been reading Yudi Pawitan's <a href="http://books.google.ie/books/about/In_All_Likelihood.html?id=M-3pSCVxV5oC&redir_esc=y" rel="nofollow">book</a>, In All Likelihood.</p>
<p>In the book, there's a section on profile likelihood; the methods explored in this section are subsequently applied to som... | g63066 | [
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-0.0022466774098575115,
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0.011749351397156715,
0.03175408020615578,
0... |
<p>I am currently studying the following case of Neil Owen, based on the following article I found a newspaper:</p>
<blockquote>
<p>"A 20-year-old student was jailed for life yesterday for the brutal
rape and murder of a schoolgirl, after one of the biggest DNA testing
programmes in British criminal history. Nei... | g63067 | [
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0.012057280167937279,
-0.03... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/53/pca-on-correlation-or-covariance">PCA on Correlation or Covariance?</a> </p>
</blockquote>
<p>I recently used R for some analysis, and encountered the options offered with PCA. The details can be found ... | g49660 | [
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-0.0099481251090765,
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-0.004261401481926441,
... |
<p>My colleague has an experiment with a 2x2 all between subjects design with categorical variables predicting a three-level categorical dependent variable (choise between A, B, C/ coded as -1 0 1). Is this coding correct? Can a dependent variable have three levels?
What kind of analysis can he best conduct?</p> | g20547 | [
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0.008752050809562206,
0.005304105579853058,
0.0122057022526... |
<p>I have two curves and I want to be able to calculate the probability of these curves coming from different distributions or another appropriate statistic.</p>
<p>Each curve is fitted through the mean of clusters of data (x's and o's in diagram) at differing points on the x-axis, each data cluster is also non-parame... | g63068 | [
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0.027726177126169205,
0.02431393787264824,
0.0807698667049408,
... |
<p><a href="http://www.quora.com/What-is-an-intuitive-explanation-of-the-difference-between-parametric-and-nonparametric-statistical-tests" rel="nofollow">Difference between parametric and nonparametric statistical tests</a> and <a href="http://stats.stackexchange.com/questions/49011/what-is-the-difference-between-dist... | g22565 | [
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0.05961914360523224,
-0.... |
<p>We're using logistic regression to predict events probability. Logistic regression tries to minimize the residual variance (sum of squared residuals). However, in our specific problem we would like to use a different loss function (for the errors in the logistic regression).
Does anyone knows any implementation (or... | g63069 | [
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... |
<p>Assume there are 16 people in a group, and each day 11 people are randomly selected from the group. Over a year, some people will be selected more times than other people.</p>
<p>The question is, assume the person selected most often was selected $M$ times, and the person selected least often was selected $m$ times... | g39761 | [
-0.018631596118211746,
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... |
<p>I recently discovered the many tools of point patterns analysis and this is a very interesting field.</p>
<p>I read a lot about how to look for deviations from complete spatial randomness (CSR) and I am able to analyze a point pattern at different scales using first- and second-order functions.</p>
<p>However, I n... | g25638 | [
0.021628348156809807,
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0.04530225321650505,
0.01217093225568533,
0.07234293222427368,
0.... |
<p>I am doing a social science research on behaviour. A purchase intention.
I have intention to purchase as dependent variable,
attitude as predictor and extraversion as moderator.</p>
<pre><code>DV = intention to purchase
step 1
attitude (center)
extraversion (center)
step 2
Attitude X extraversion (center)
</code></... | g63070 | [
-0.009836078621447086,
0.05381234362721443,
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0.018984787166118622,
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0.04559275880455971,
0.011714207008481026,
-0.0... |
<p>I have written some code that implements a neural network which solves the <code>XOR</code> problem.
I have a function <code>h</code> that receives 2-D points and the network matrices at each layer and computes the output of the net on that point. </p>
<p>Now, what I want is to visually examine the decision bounda... | g63071 | [
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0.0020007228013128042,
0.020815497264266014,
0.050312355160713196,
0.08203191310167313,
0.0226... |
<p>I have data of the following format:</p>
<p>Attr1,Attr2,Attr3....Attrn,Outcome</p>
<p>(All attributes and outcome are numeric)</p>
<p>I want to find out:
1. With what values of each attribute will the Outcome be minimum?
2. What attributes are most responsible for minimizing the Outcome?</p> | g63072 | [
0.03651542216539383,
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0.0008582925074733794,
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0.008530945517122746,
0.025508305057883263,
... |
<p>Consider the following model for $Y_t$:</p>
<p>$\Delta$log($Y_{T+1})$ = $u_T$ where $u_T$ ~ IID Normal(0,$\sigma^2$).</p>
<p>I want to forecast $Y_{T+1}$. Taking exponentials and then expectations, we see that </p>
<p>$E(Y_{T+1}|\Omega_T)$ = $Y_T E(e^{u_{T+1}}|\Omega_T)$ = $Y_TE(e^{u_{T+1}})$ since $u_{T+1}$ is I... | g63073 | [
-0.03463144972920418,
0.01818445511162281,
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0.0568511001765728,
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0.... |
<p>Where can I get an explanation of the procedure used when making a prediction using SVD? </p>
<p>Let me elaborate a bit more. Suppose you have data in a matrix $A$ containing two classes. In particular, you could have $m$ attributes and $n$ objects. Half of the objects belong to the first class and the other half b... | g8519 | [
0.017385177314281464,
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0.0389745756983757,
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0.037... |
<p>I have the following hourly time series data and would like to fit a best fit line to it:</p>
<p><img src="http://i.stack.imgur.com/B03jZ.png" alt="enter image description here"></p>
<p>There seems to be a periodicity on a daily basis and a weekly basis. By this, I mean there are patterns that repeat every day (e... | g63074 | [
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0.057980842888355255,
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0.06636317819356918,... |
<p>It seems that the consensus is that after fitting a linear regression via OLS, when you have included a lagged dependent variable (because it is supported by theory or appears needed based on the data) such as the following AR(1):</p>
<p>$y_{t}=\beta_{0}+\beta_{1}y_{t-1}+\beta_{2}x_{1}+e_{t}$</p>
<p>the resulting ... | g63075 | [
0.041555002331733704,
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... |
<p>I have this confusion. In ordinary kriging we have used the unbiasedness condition which gave the sum of weights equal to one. However, in the case of simple kriging we have no such conditions why?</p>
<p>I used ordinary kriging and simple kriging in my dataset and I have a huge difference in kriging in predicting ... | g20558 | [
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0.003931133542209864,
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0.0052151745185256,
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0.037891801446676254,
0.02... |
<p>I need to find the distribution of the random variable
$$Y=\sum_{i=1}^{n}(X_i)^2$$
where $X_i\sim{\cal{N}}(\mu_i,\sigma^2_i)$ and all $X_i$s are independent. I know that it is possible to first find the product of all moment generating functions for $X_i$s, and then transform back to obtain $Y$'s distribution. Howe... | g49816 | [
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-0.0008531045168638229,
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0.027824198827147484,
0.014758431352674961,
... |
<p>Given a set of data with many independent variables and a single dependent variable how can I find the "experimental region" of the resulting model? This is the region within which we can make valid predictions and doesn't go outside of the bounds of the data we were provided. Also what is a good way to articulate t... | g20560 | [
-0.017992468550801277,
0.02469748817384243,
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-0.070586659014225,
0.03049912303686142,
0.02855060249567032,
0.03265927731990814,
-0.005... |
<p>Suppose I am testing two drugs, I and II. The response profile is either I > II, I < II or I = II. I was trying to figure out if I is in fact better than II. </p>
<p>One way I thought of was to throw out all the ties (I == II), and then assign a 1 where I > II and a 0 where I < II.
Then this boils down to a ... | g63076 | [
0.023601306602358818,
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0.022280164062976837,
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0.016739631071686745,
0.0019111853325739503,
0.020695336163043976,
0.008746379986405373,
... |
<p>I have a situation where I have 3 treatments/conditions A, B, C. For each condition I have multiple trials. </p>
<p>I compare the means of trials under each condition A, B and C. This gives me 3 values.</p>
<p>Then I am computing a difference A-B and A-C. I need to obtain confidence interval/error bars for the sin... | g63077 | [
-0.028094496577978134,
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0.008123280480504036,
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0.037737950682640076,
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0.013790135271847248,
0.049188558012247086,
0.015229272656142712,
... |
<p>I need to build a HMM with two chains: the structure is as the figure below. How can I use the Viterbi algorithm for this model?</p>
<p><img src="http://i.stack.imgur.com/mW1gB.jpg" alt="enter image description here"></p> | g63078 | [
0.04653173312544823,
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0.050223320722579956,
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0.013668738305568695,
-0.011513285338878632,
-0.01804846152663231,
0.023542257025837898,
-0.00... |
<p>Is Maximum Entropy rule equivalent to non-informativeness? </p>
<p>In other words, when maximizing the entropy of a distribution, given some known stuff, is it equivalent to finding to most non-informative distributions?
If so, how do you justify this mathematically? </p> | g63079 | [
0.0352218933403492,
0.017369795590639114,
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0.03439735248684883,
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0.045859575271606445,
0.... |
<h3>Description</h3>
<p>I have 1D data with $N$ normally distributed clusters. I have to find a cluster, which is the worst (differs at most from the normal distribution). </p>
<h3>My approach</h3>
<p>I calculate $sq = \frac{(f(x) - y)^2}{\#y}$, where $f(x)$ is value of normal PDF with mean equal to the center of th... | g19150 | [
0.023855237290263176,
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0.029391467571258545,
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0.018484722822904587,
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-0.007176780141890049,
0.01531527191400528,
0.038035452365875244,
0.05338726192712784,
-0... |
<p>I am trying to estimate the mean of a variable for 2 different groups. If in Stata I use </p>
<pre><code>. bys group: sum variable
</code></pre>
<p>I'll get the mean. However, there are differences among two groups in terms of age, gender, education... And I have to control for that. To be more clear, let's say m... | g63080 | [
-0.013624404557049274,
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0.001523361774161458,
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0.019104260951280594,
0.0004146024875808507,
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0.04525638371706009,
0.013793178834021091,
... |
<p>Although there are doubtless many techniques for studying the impact of a discrete intervention over time, I am interested in two which have achieved widespread adoption in the social sciences:</p>
<ul>
<li><a href="http://econometricsense.blogspot.com/2012/01/intervention-analysis.html" rel="nofollow">Interrupted ... | g63081 | [
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0.014949021860957146,
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0.00621965853497386,
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0.05397272855043411,
0.024157501757144928,
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0.0065354653634130955,
0.0473843589425087,
-0.005886086728423834,
0.03232688084244728,
-0.03... |
<p>I am a bit confused with the basic time series terminology:</p>
<p>Consider the following words:</p>
<ul>
<li><p>fitted values</p></li>
<li><p>forecasted values</p></li>
<li><p>in-sample forecasts</p></li>
<li><p>out-of-sample forecasts</p></li>
<li>in-sample fit</li>
</ul>
<p>I am using GARCH models in my thesis... | g63082 | [
0.0423281267285347,
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0.0015491978265345097,
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0.039778999984264374,
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0.028607016429305077,
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0.059325654059648514,
0.02645053155720234,
-... |
<p>We're designing a trial to test four factors (call them <code>A</code>, <code>B</code>, <code>C</code> and <code>D</code>) for an experiment. Each factor has two levels: <code>+</code> and <code>-</code>. The <code>+</code> of factor <code>A</code> is believed to lead to better results and the <code>-</code> of fact... | g20564 | [
0.018836287781596184,
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0.0520579069852829,
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0.0024121743626892567,
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-0.08881634473800659,
0.006342893932014704,
0.05684206634759903,
0.03608277812600136,
-0... |
<p>I am trying to devise a measurement of neural network saturation for my NN saturation study. Some background: saturation occurs when a hidden neuron outputs values close to the extremes (usually 0 and 1), and practically nothing in-between. Neuron paralysis occurs when a neuron always outputs a similar value, regard... | g63083 | [
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0.06697382777929306,
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0.016044968739151955,
0.07771831005811691,
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-0.0021886657923460007,
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-0.00027332035824656487,
0.01247398089617490... |
<p>I need your help to identify group means and calculate the corresponding 95% confidence intervals for a set of independent samples with 2 dependent observations within each of those samples. I'm using R with the <code>NLME</code> package. Below is a simplified example with a similar structure to my actual data.</p>
... | g63084 | [
0.00327607081271708,
-0.04699632525444031,
-0.015467578545212746,
-0.014221417717635632,
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0.06002861633896828,
-0.026081345975399017,
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-0.035389531403779984,
0.019425397738814354,
0.02940191701054573,
0.023142730817198753,
-... |
<p>As far as I can tell, <em>curvilinear</em> is defined vaguely but means the same as <em>nonlinear</em>. Is that correct? Or does <em>curvilinear</em> have a distinct definition?</p> | g63085 | [
0.04246331378817558,
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0.10318325459957123,
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-0.004835615400224924,
-0.03939015790820122,
0.0036247672978788614,
0.020186547189950943,
-... |
<p>I am curious as to when the derivative of a marginal df is equal to the marginal pdf for a (continuous) random variable.</p>
<p>As a simple example, let Z = (X,Y) be a continuous random vector and F be the df of Z. Assuming the processes of integrating and differentiation can be exchanged, then it would seem like ... | g63086 | [
0.08021435141563416,
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-0.0017438074573874474,
... |
<p>My question is about what method to use for a mixed between-within design when the relationship between the covariate and the DV is non-linear (quadratic).</p>
<p>My DV is reasoning task score. There are two types of questions in the task - let's call them "control" and "test" questions.</p>
<p>My IVs are question... | g24575 | [
-0.013837321661412716,
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0.005369577091187239,
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0.061338312923908234,
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0.030934732407331467,
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0.0444154292345047,
... |
<p>For a simulation study I have to generate data according to a trivariate mediation model (Baron & Kennys causal step approach). Assuming $X$, $M$, and $Y$ are continuous variables of sample size $n$, the following regression equations constitute the data generating process: </p>
<p>$M = \alpha + aX + \epsilon$<... | g63087 | [
0.036393746733665466,
-0.08663821965456009,
0.0020471704192459583,
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0.005984182469546795,
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-0.017836764454841614,
0.0070172990672290325,
-0.009274598211050034,
0.015933869406580925... |
<p>I have a treatment group and two control groups for customers and the count of their transactions:</p>
<pre><code>Treatment Group
Customer | Transaction Count
-----------------------------
1 | 0
2 | 2
3 | 3
4 | 0 ...
Control Group 1
Customer | Transaction Count
-------------------------... | g20568 | [
0.01895987056195736,
0.010627379640936852,
-0.005082943942397833,
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0.029816539958119392,
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0.007253699470311403,
0.021488064900040627,
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-0.013393341563642025,
0.057171531021595,
0.039316631853580475,
0.029640929773449898,
0.04... |
<p>I'm using glmnet for building the regression models.
My data are already log-transformed. when I scale my data set (zero mean, and SD=1), I get the following error:</p>
<pre><code>Error in elnet(x, is.sparse, ix, jx, y, weights, offset, type.gaussian, :
NA/NaN/Inf in foreign function call (arg 5)
</code></pre>
... | g20569 | [
0.049862075597047806,
0.031732816249132156,
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0.05680113658308983,
0.037508800625801086,
-0.042... |
<p>This question doesn't specifically pertain to <code>R</code>, but I
chose to use <code>R</code> to illustrate it.</p>
<p>Consider the code for producing confidence bands round a (normal) qq-line:</p>
<pre><code>library(car)
library(MASS)
b0<-lm(deaths~.,data=road)
qqPlot(b0$resid,pch=16,line="robust")
</code>... | g63088 | [
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0.037694282829761505,
0.05994086712598801,
-0... |
<p>Could you please recommend methods for combining classifiers, which were trained on different patients? For example, there are 10 patients and for each of them I trained a binary classifier. Now I want to combine the classifiers I already have by taking weighted average of their predictions, so my question is how to... | g63089 | [
0.030141830444335938,
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0.03087853081524372,
0.08124293386936188,
-0.0... |
<p>I've read multiple posts on model fitting using <code>lmer()</code>, but I saw multiple versions of using the error term which made it confusing for me. I have a factorial design with 2×2×2 with one between and two within factors. I do an eyetracking task in which participants are in one of two sound con... | g13860 | [
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0.028047960251569748,
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0.042399756610393524,
... |
<p>I make a certain measurement and I would like to arrive at a single descriptive number that would give me an idea of both the average value of the measurement, as well as the deviation from the mean. In fact, the deviation (general extent - how far do the values go?) interests me more than the mean, but I am aware t... | g11069 | [
-0.050895534455776215,
0.06350170075893402,
-0.025352122262120247,
-0.025907142087817192,
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-0.024344926699995995,
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0.019681012257933617,
0.059742096811532974,
... |
<p>I use the caret package for training a randomForest object with 10x10CV. </p>
<pre><code>library(caret)
tc <- trainControl("repeatedcv", number=10, repeats=10, classProbs=TRUE, savePred=T)
RFFit <- train(Defect ~., data=trainingSet, method="rf", trControl=tc, preProc=c("center", "scale"))
</code></pre>
<p>... | g17218 | [
-0.011869648471474648,
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0.03262733295559883,
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<p>I wonder if anyone has put into use the autoregressive metric for ARIMA clustering proposed by <a href="http://dx.doi.org/10.1016/j.csda.2007.06.001" rel="nofollow">Corduas and Piccolo (2008)</a>.
The authors define the distance autoregressive metric between two processes $X, Y$ as: </p>
<p>$$\text{d}(X,Y)=\sum_{j=... | g288 | [
0.02977469190955162,
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0.016062570735812187,
0.04918839409947395,
0.09434729069471359,
-... |
<p>I've got a set of multivariate regression models, with weights, that I'm trying to compare in R. Looks like:</p>
<pre><code>f0 <- lm(cbind(Y1,Y2,Y3,Y4) ~ co1 + co2 + co3 + co4 + x1, dat, weight=wt)
f1 <- lm(cbind(Y1,Y2,Y3,Y4) ~ co1 + co2 + co3 + co4 + x1 + x2, dat, weight=wt)
f2 <- lm(cbind(Y1,Y2,Y3,Y4) ~ ... | g63090 | [
0.017264217138290405,
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<p>I am specifying a sample of weekly work records to be entered into a spreadsheet for an estimation of means on two variables. There are about 250 employees, I am only interested in weeks between a specific date and the present, the total universe of possible work weeks is 28,538. Because we wanted to assure that t... | g47480 | [
-0.0007954919710755348,
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0.006323632318526506,
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0.03325624763965607,
0.0027564906049519777,
... |
<p>A retrospective cohort study basically is classifying people based on exposure status. The disease and exposure have already occurred. So we can also classify people based on cases and look at whether they were exposed or not. Thus can we change a retrospective cohort study into a case-control study?</p> | g63091 | [
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<p>I want to write a discrete event simulation. I downloaded bus traces (long. and lati. (x and y coordinates)) data from crowded group at Darmouth. When I run statistics tests, x and y data are correlated, so I cannot consider them as two separate distributions. Traditionally, we have a probability distribution, and w... | g63092 | [
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0.003698508720844984,
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0.04005865752696991,
0.00... |
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