question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Let's say I have a logistic regression classifier. In normal batch learning, I'd have a regularizer term to prevent overfitting and keep my weights small. I'd also normalize and scale my features.</p>
<p>In an online learning setting, I'm getting a continuous stream of data. I do a gradient descent update with each... | g66096 | [
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<p>This is perhaps a very basic question, but I am a bit confused. I have a time series of day some time varying data, say the amount of sunlight as the day passes.</p>
<p>I bucket the data in say 10 bins say according to just time, so later bins occur later in time and calculate the variance of each of the bins. Is t... | g24971 | [
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<p>I am measuring secretion of insulin upon glucose stimulation of pancreatic islets after various treatments.
So I have two independent variables/factors:</p>
<ol>
<li><strong>Treatment</strong> (three different compounds and a control treatment)</li>
<li><strong>Glucose concentration</strong> (<em>low</em> and <em>h... | g66097 | [
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<p>I am using R to find the value of lambda by cross-validation for ridge regression but the problem is my code as follows does not work for such a big matrix. Any help would be highly appreciated. Thanks in advance. My own work is </p>
<pre><code># X<- my own dataset which has n=205 observations by 18856 variables... | g66098 | [
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<p>Let $X$ be a categorical random variable with possible outcomes $o_1,...,o_n \subset [l, u]$ (real numbers with a known lower bound $l>0$ and known upper bound $u$) that occur with probability $p(X = o_i) = p_i$ for all $i$ and the probabilities sum to one, $\sum_{i=1}^n p_i = 1$.</p>
<p>This random variable can... | g66099 | [
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<p>Suppose there are $6$ people in a population. During $2$ weeks $3$ people get the flu. Cases of the flu last $2$ days. Also people will get the flu only once during this period. What is the incidence density of the flu?</p>
<p>Would it be $\frac{3}{84 \text{person days}}$ since each person is observed for $14$ days... | g66100 | [
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<p>I've just played a game with my kids that basically boils down to: whoever rolls every number at least once on a 6-sided dice wins.</p>
<p>I won, eventually, and the others finished 1-2 turns later. Now I'm wondering: what is the expectation of the length of the game?</p>
<p>I know that the expectation of the numb... | g49857 | [
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<p>I'm attempting to learn Bayesian modelling with PyMC, so I have been going through Cam Pilon Davidson's <em>Probabilistic Programming for Hackers</em>. I literally copied his code from chapter 1 and used my own storm data. Here is the <a href="http://nbviewer.ipython.org/urls/dl.dropbox.com/s/0dg3mqs0h43ae42/Cross%2... | g49345 | [
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<p>I am wondering how can I estimate $ \alpha $ in the following carryover recursive estimation:</p>
<p>$ \lambda_i = \alpha_\lambda \cdot \lambda_{i-1} + (1-\alpha_\lambda) \cdot y_{i-1} $</p>
<p>I have read <a href="http://www.clinchem.org/content/34/9/1805.full.pdf" rel="nofollow">Estimating Within- and Between-Me... | g24975 | [
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<p>I understand naive Bayes is used largely in text classification. However, the number of features tend to outnumber the number of documents. Does this not result in overfitting where the number of parameters outweigh the number of samples. </p>
<p>I am trying to classify a set of documents using multinomial naive Ba... | g24977 | [
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<p>I'm testing the hypothesis that the <strong>the variance observed in the number of medical consultations felt from 2009 through 2013 is due to the variance in user fees price</strong>, and not due to something else.
I have 3 time series (from Jan. 2009 to Dec. 2013, measured quarterly) corresponding to the followin... | g66101 | [
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<p>Imagine we have the following mixed model</p>
<pre><code>mod <- lmer(y ~ x + z +(1|g), data = dat)
</code></pre>
<p>where:</p>
<pre><code>y <- 1:12
x <- 1:12 + rnorm(12)*2
z <- 1:12 + rnorm (12)^2
g <- c(letters[1:4], letters[1:4], letters[c(1,2,5,6)])
dat <- data.frame(y=y,x=x,z=z,g=g)
</code><... | g66102 | [
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<p>I aimed at studying the effects of an exposure (E) on fetal growth estimated by repeated ultrasound measurements (n = 2 measures per participant in the following example).
I used interaction terms of gestational age with exposure, in order to compute the effect of exposure at different age (using <code>lincom</code... | g66103 | [
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<p>I'd like to generate a series that follows an IMA(1,1) process, where $θ$ is the moving average parameter. I generated the series based on different representations and I got different results, I'm wondering which one is correct?
$$
\begin{aligned}
d_1 &=μ+e_1 \\
d_t &=d_{t−1}−θ\cdot e_{t−1}+e_t \\ \\
\te... | g24984 | [
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<p>In an AR model the coefficients on the lags can be solved for using least squares. How is the MA part of ARMA solved for? Since the MA part is a sum of white noise terms I imagine that it is not solved using least squares. </p> | g37425 | [
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<p>Can anyone provide a reference for the Continuous Space Hill Climbing Algorithm pseudocode in the Wikipedia article on Hill Climbing? The Russell and Norvig text is cited, but they only provide the discrete case. I'm wondering where this particular version of the continuous case is first described.</p>
<p><a href="... | g24985 | [
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<p>As suggested in <a href="http://stats.stackexchange.com/questions/47685/calculating-log-likelihood-for-given-mle-markov-chains">Calculating log-likelihood for given MLE (Markov Chains)</a> I want to perform a likelihood ratio test for two fitted models (i.e., first and second order markov chains). Simply comparing t... | g40442 | [
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<p>Consider an infinite random geometric graph in which the node locations follow a Poisson point process with density $\rho$ and edges are placed between the nodes that are closer than $d$. Therefore, the length of the edges follow the following PDF:</p>
<p>$$
f(l)=
\begin{cases}
\frac{2 l}{d^2} \;\quad l \le d \\
0 ... | g66104 | [
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<p>Why do people very rarely report the calibrated p-value which is: $$\mathcal{P}(p) = \frac{-ep \log(p)}{1-ep \log(p)}$$</p>
<p>This gives the probability that one falsely rejects the null hypothesis (i.e. Type 1 error). It is a lower bound. </p> | g37971 | [
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<p>I would like to use the stlf forecast function from the R package forecast (http://cran.r-project.org/web/packages/forecast/index.html) and include regressors in the model.</p>
<p>Question 1: This can only be done using "" method="arima" "" - right?</p>
<p>Question 2: For the model calibration the parameter "xreg... | g24986 | [
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<p>If I randomize time points $$T=\{266.14646, 107.28526, 108.89631, 593.03129,\\ 118.10284, 425.60470, 39.02817, 291.90210\}$$ into two groups of equal size, then what is the probability that $T_i$ (the $i$-th time point) will be the 3rd order statistic of the second group? </p>
<p>Given that $T_i$ follows an exponen... | g38379 | [
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<p>I am trying to produce a model for which I have a response variable which is a proportion between 0 and 1, this includes quite a few 0s and 1s but also many values in between. I am thinking about attempting a beta regression. The package I have found for R (betareg) only allows values in between 0 and 1 but not inc... | g66105 | [
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<p>I am quite new to R so apologies if I fail to ask properly. I have done a test comparing bat species richness in five habitats as assessed by three methods. I used a linear mixed model in lme4 and got habitat, method and the interaction between the two as significant, with the random effects explaining little variat... | g66106 | [
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<p>I've been asked by a reviewer if the Pearson correlations (r-values) presented in a table can be compared to each other so one can claim that one is "stronger" than another (other than just eyeballing the actual r-values).</p>
<p>How would you go about this? I've found this method</p>
<p><a href="http://vassarstat... | g66107 | [
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<p>Assume I test a number of patients repeatedly over time to see how a certain treatment changes their skin conductance in response to a certain colour (<code>cond</code>) after 2 months, 4 months, ... etc. I test the skin conductance on the palm, wrist or arm simultaneously to see whether the place matters.</p>
<p>I... | g66108 | [
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<p>I'm currently searching the web and literature for streaming classification datasets with concept drift. I've found a number of synthetic datasets where over time the important predictors either change in their "predictive" nature.</p>
<p>For example here is a <a href="https://www.google.com/url?sa=t&rct=j&... | g24987 | [
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<p>A series with drift can be modeled as
$y_t = c + \phi y_{t-1} + \epsilon_t$
where $c$ is the drift(constant), and $\phi=1$</p>
<p>A series with trend can be modeled as
$y_t = c + \delta t + \phi y_{t-1} + \epsilon_t$
where $c$ is the drift(constant), $\delta t$ is the deteministic time trend and $\phi=1$</p>
<p>... | g29471 | [
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<p><a href="https://en.wikipedia.org/wiki/Analysis_of_variance" rel="nofollow">Wikipedia</a> says:</p>
<blockquote>
<p>Analysis of variance (ANOVA) is a collection of statistical models used to analyze the differences between group means and their associated procedures (such as "variation" among and between groups).... | g24992 | [
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<p>I performed a regression analysis about the impact population increase, precipitation, and difference in registered voters in 2012 versus 2008 against the total of ballots cast in 2012 versus 2008. The ratio showed Y= -889.8x - 11837 R2= 0.0751
Does that mean the independent variables greatly affected the depe... | g66109 | [
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<p>I have data for a test on three groups. The measured variable is ratio scaled. The R code is</p>
<pre><code>g1a<-c(7, 3, 40)
g2a<-c(1,1,2)
g3a<-c(0,0,0)
</code></pre>
<p>Since the sample is small and normality cannot be guaranteed, I run a Kruskal Wallis test to check for significance:</p>
<pre><code>l&l... | g24996 | [
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<p>I am currently working with a dataset where the data are weighted, contain missing values and violate assumptions of multivariate normality. Specifically, I have built a structural model using Stata - and am wondering if I have attended to these issues properly by using the following techniques. </p>
<ol>
<li><p>AD... | g66110 | [
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<p>If I have highly dimensional data and perform k means clustering, I can end up with clusters that differ more on some axes than others.</p>
<p>SPSS provides the option to return an ANOVA for each variable, which shows if the variance is significant between clusters. Is it possible to break this down into pairs of c... | g24997 | [
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<p>I am working on some applied research. I have a small non-random sample ($n=90$), and many variables $>50$ IVs (mix of nominal, ordinal, interval) and 6DVs. The data collection instrument itself was obviously broad (but items chosen were due to known relationships or theorised relationships in the past) so as to ... | g24998 | [
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0.005678895860910416,
0.03... |
<p>Let's say we have $n$ patients and we did $l_i$ measures of some parameter at the left side of the patients and $k_i$ measures of the same parameter at the right side of them. So we got a table like this:</p>
<pre><code>i left side right side
1 0.1 0.2 0.9 0.5 -0.3 0.5 1.3 0.9 -0.6 1... | g29833 | [
0.006212133914232254,
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0.0446007177233696,
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-0.016676263883709908,
-0.04114793241024017,
0.06178084388375282,
0.0124331284314394,
0.032... |
<p>We consider the model of nonparametric regression:</p>
<p>$$Y_{i}=f(X_{i})+\xi_{i}$$</p>
<p>with $f:[0,1]\rightarrow \mathbb{R}$, $\xi_{i}$ are i.i.d with density $p_{\xi} $ with respect to the Lebesgue measure on $\mathbb{R}$ and $X_{i}$ are deterministic.</p>
<p>Somebody can explain me why $P_{j}$(the distribut... | g25000 | [
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0.0160042904317379,
0.0039420947432518005,
0.0164... |
<p>I'm a programmer, with a decent but not-expert knowledge of stats, and I'm working through <a href="http://stats.stackexchange.com/questions/29220/calculating-standard-error-for-funnel-plots">these instructions for how to create funnel plots</a>. </p>
<p>I <a href="http://stats.stackexchange.com/questions/29220/cal... | g35789 | [
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<p>(1) (3 points each) John has come up with a unique new remedy for insomnia. He knows that in the absence of his remedy insomniacs sleep an average of 250 minutes a night with a standard deviation of 30 minutes. He believes that his remedy can increase the average minutes slept per night to 300 minutes and that his... | g66111 | [
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... |
<p>The p-postulate is the notion that equal p-values provide equal evidence against the null hypothesis.</p>
<p>Royall, R. N. (1986). <a href="https://dl.dropboxusercontent.com/u/53771404/Royall%201986.pdf" rel="nofollow">The Effect of Sample Size on the Meaning of Significance Tests</a>, The American Statistician, 40... | g47185 | [
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<p>I have a dataset of many discrete counts (RNAseq read counts per base), which contain both real signals and background noise. The noise is random, and should be poisson distributed. </p>
<p>What I would like to do is to subtract (or set a threshold for) a baseline that roughly equals the mean of the noise + a CI, b... | g66112 | [
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0.00989209022372961,
0.00... |
<p>the result of SPSS is uploaded in image form.<img src="http://i.stack.imgur.com/bFutx.png" alt="enter image description here"></p>
<p>This is exactly a part of my HW. And it make me confused for like 1 hour.
Use the Tukey HSD procedure in SPSS to determine which levels of the factor differ. State your conclusions b... | g66113 | [
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<p>As I've heard of the AdaBoost classifier repeatedly mentioned at work, I wanted to get a better feel for how it works and when one might want to use it. I've gone ahead and read a number of papers and tutorials on it which I found on Google, but there are aspects of the classifier which I'm still having trouble unde... | g25005 | [
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<p>I need to know how to find the Bayesian probability of two discrete distributions. For example the distributions are given as follows:</p>
<pre><code>p(y/x) = (start= 100, values = 0.1, 0.4, 0.5);;
p(x) = (start = 150, values = 0.1,0.1,0.1,0.3,0.3,0.1)
</code></pre>
<p>and the Bayesian formula is given <code>p(x/y... | g66114 | [
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<p>I am preparing a complex survey data for analysis. The survey involved a two-stage stratified cluster sampling. In the first stage, I have 7 strata and 14 sampling units and in the second stage I have 13 strata and 29 sampling units. I have made sure that there are at least 2 sampling units per sampling stratum. How... | g18490 | [
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<p>I have some samples from eight people who all gave the same answer to a question. Now, obviously the sample's mean is the answer all people gave, and the standard dev is 0. Excel throws a <code>#NUM!</code> error when I call the function</p>
<pre><code>CONFIDENCE.T(0.05, K33, COUNTA(B33:I33))
</code></pre>
<p>wher... | g66115 | [
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<p>I need your help with a Statistical Learning homework in R.
I have to perform classification over this dataset: <a href="http://archive.ics.uci.edu/ml/machine-learning-databases/mammographic-masses/" rel="nofollow">mammographic masses</a> predicting Severity (0="not severe",1 = "severe) using these predictors:</p>
... | g66116 | [
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0.0042729973793029785,
0.02173186093568802,
0.051787298172712326,
0.0904897153377533,
-0.014... |
<p>Hi I am trying to find the non-parametric equivalent of a two-way ANOVA (3x4 design) which is capable of including interactions. From my reading in Zar 1984 "Biostatistical analysis" this is possible using a method put forth in Scheirer, Ray, and Hare (1976), however, according to other posts online it was inferred ... | g49405 | [
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0.0011351542780175805,
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0.018869701772928238... |
<p>I'm working on a calibration problem which involves the usage of the Kullback-Leibler divergence as an error between some empirical distribution $p$ and a theoretical distribution $q$. In the model, the $q$ distribution is normal with some fixed parameters. I have two questions: </p>
<ol>
<li>Is the Kullback-Leibl... | g25011 | [
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0... |
<p>I understand EM algorithm is often used for missing data/mixture problem. But can it be used to optimize a particular type of likelihood based on jointly fitting variables and transformations of those variables? </p>
<p>I am fitting a logistic regression model: $Y$ is the usual binary dependent variable, $\mathbf{X... | g66117 | [
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... |
<p>Our project involves looking at different chemical properties and developing a model which incorporates first and second order effects to predict properties of new chemicals. The data set consists of 100 obs. and 40 variables. The following approach worked when there were no second order effects involved. How can I ... | g66118 | [
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0.04357697069644928,
-... |
<p>$$
f(x)= \frac{x^{(\alpha−1)} * (1−x)^{(\beta−1)}}{\mathcal B(\alpha,\beta)}
$$</p>
<p>Questions: </p>
<ol>
<li>How can we derive this famous pdf? </li>
<li>What is the intuitive meaning of the Beta distribution? (Please don't give the baseball example). </li>
<li>Please give some numerical problems with solution... | g49741 | [
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<p>I'd like to compare some Jazz tunes.</p>
<p>Jazz tunes are characterized by a succession of chords. The interval between each succeeding chord (number of tones) and the order in which they appear matter.</p>
<p>At first, I thought of a Mann-Whitney test that could compare two tunes with a different number of chord... | g66119 | [
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0.009505276568233967... |
<p>I have a survey where respondents rate a product on different scales such as design, quality etc, which several questions for each category. I've run a factor analysis and found six meaningful factors from which I've derived factor scores. How would my regression differ if I used these factor scores for a multiple r... | g66120 | [
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0.... |
<p>I have a function that I am trying to optimize using Particle Swarm Optimization. </p>
<p>The objective function gets a binary string. These binary strings are candidate solutions of the subject function. I can measure the dissimilarity between two solutions by the <a href="http://en.wikipedia.org/wiki/Jaccard_inde... | g66121 | [
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<p>With a colleague, we are working on a dataset containing ~5000 continuous variables for 120 individuals belonging to 8 classes.</p>
<p>We want to <strong>estimate the relative importance of each variable</strong> to explain the classes.
We have used a random forest approach with some success.
Now, we could like to ... | g66122 | [
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... |
<p>From the help documentation of the <code>discretize</code> function of the R package <code>bnlearn</code>: </p>
<blockquote>
<p>Hartemink's algorithm has been designed to deal with sets of
homogeneous, continuous variables</p>
</blockquote>
<p>Does "homogeneous" here mean that the variables should share a comp... | g66123 | [
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0.030426383018493652,
0.00774219399318099,
0.05525422468781471,
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0.06... |
<p>I have fitted the exponential and gamma model to my univariate data and obtained the MLE estimates using the R package "fitdistr", now I'm trying to do model selection based on leave-one-out cross validation, are there any readily avaliable R package to do this. </p>
<p>Thanks!</p> | g66124 | [
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<p>I conducted a survey research where I have used two delivery modes for the questionnaire - online and offline (hardcopy mode). </p>
<p>The survey questions measure perceptions of employees on certain organisational behavior variables such as - organisational commitment, organisational justice, perceived organisatio... | g66125 | [
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0.... |
<p>I was double-checking my regression outputs in WEKA and Excel. All coefficients are the same, however I get a considerably different intercept. How come?</p>
<p>Also, is it possible to run a t- or p-test or any other significance test in weka (as is included in the Excel regression)?</p>
<p>My dependent variable a... | g72 | [
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0.05260927975177765,
0.06227390468120575,
-0.0... |
<p>The Validity Index "Pseudo F" is described as:</p>
<p>(between-cluster-sum-of-squares / (c-1)) / (within-cluster-sum-of-squares / (n-c))</p>
<p>with c beeing the number of clusters and n beeing the number of ovservations. It measures the seperation between all the clusters and should be high.</p>
<p>I want to app... | g25014 | [
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0... |
<p>I'm new to linear mixed modeling, and have some theory-driven questions that I'm not sure how to analytically resolve.</p>
<p>I am analyzing experimental data with a within-subjects factor (<code>discount</code>). My theory hypothesizes that the effect of this within-subjects factor is contingent upon a between-sub... | g25015 | [
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0.023558007553219795,
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0.009713978506624699,
... |
<p>It seems when I glance around here at the fashionable learning algorithms, things like neural networks, boosted trees, support vector machines, random forests, and friends are promoted for supervised learning problems. Dirichlet processes and their ilk seem to be mentioned mostly in unsupervised learning problems, s... | g25016 | [
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0.0323333777487278,
0.005311212968081236,
-0.042381759732961655,
0.04286503046751022,
-0.010935318656265736,
0.08499643206596375,
0.0001... |
<p>Apologies in advance if any of the terminology I use is incorrect. I'd welcome any correction. If what I describe as a "cut-off" goes by a different name, let me know and I can update the question.</p>
<p>The situation I'm interested in is this: you have independent variables $\bf{x}$ and a single dependent variabl... | g66126 | [
-0.009197932668030262,
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0.023971904069185257,
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0.026456110179424286,
0... |
<p>I'm working on a software project that involves creating a visualizer for flood simulations. As part of this project, I've created a water gradient that shows water depth at particular points. To set what values will represent what colors, I go through the data and get the minimum and maximum values that occur and e... | g66127 | [
-0.023484310135245323,
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0.06918659061193466,
0.06416... |
<p>I want to conduct a within-subjects experiment with one independent variable with four levels. However, I ran a few informal pilot tests, and exposing participants to all four conditions seems to negatively affect results on the later conditions. That is, participants get bored of the experiment by the second or thi... | g25018 | [
0.007040929049253464,
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0.012294511310756207,
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0.022882310673594475,
-0.06403925269842148,
... |
<p>I want to compare to incidence rate's between two groups (one without a disease and one with).</p>
<p>I was planning to calculate the incidence rate ratio (IRR), i.e. incidence rate group B/ incidence rate group A, and then test if this rate equals to 1, and finally calculate 95% CI intervals for the IRR. </p>
<p>... | g37982 | [
0.049049608409404755,
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0.003115735249593854,
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0.0571511834859848,
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0.015893714502453804,
0... |
<p>I wonder if my following understandings about <a href="http://en.wikipedia.org/wiki/Random_seed" rel="nofollow">random seeds</a> are correct:</p>
<ol>
<li><p>Uniform random generators require random seeds.</p></li>
<li><p>Non-uniform random generators depend on random seeds, only through
uniform random generators.<... | g66128 | [
-0.030606677755713463,
0.036665719002485275,
-0.002541608177125454,
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-0.01199285127222538,
-0.024636680260300636,
-0.06564932316541672,
-0.009065686725080013,
... |
<p>I am curious about some glossaries.</p>
<ol>
<li>Does "<a href="http://en.wikipedia.org/wiki/Pseudorandom_number_generator" rel="nofollow">pseudorandom number generator (PRNG)</a>" only mean for
uniform random number generator? I didn't see one that is not in
<a href="http://en.wikipedia.org/wiki/List_of_pseudorand... | g47350 | [
-0.0034446457866579294,
0.03691703453660011,
0.00803159736096859,
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0.021470751613378525,
0... |
<p>I did the code for my $R^{2}$ (R square) test in MATLAB but it is not working accordingly.
I want to test the Weibull distribution against my raw data, hence I want to do an $R^{2}$ (R square) test. Below is my code, but the results I obtain are negative. I tried with Gamma and Rayleigh to test, but the code was not... | g25020 | [
0.028126830235123634,
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0.03821641579270363,
... |
<p>An oracle can be asked a binary question. If the real answer is <em>true</em>, the oracle says true with probability <em>tt</em> (and false with probability <em>tf=1-tt</em>). If the real answer is <em>false</em>, the oracle says false with probability <em>ff</em> (and true with probability_ft=1-ff_). So the orac... | g66129 | [
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0.015836533159017563,
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0.03345290198922157,
0.0058653163723647594,
0.022... |
<p>I have the following situations : </p>
<p>(1) <strong>Very large number of variables</strong> - say 100 variables and 200 samples (observations). Although level of each variable is just 2 or 3 or 4 max. I am doing linear ANOVA to test the hypothesis.</p>
<p>Say, for the first variable, <code>Ho: l1 = l2 = l3 = l4<... | g25023 | [
0.043064430356025696,
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0.011381881311535835,
0.009000507183372974,
0.01643317937850952,
0.030457010492682457,
... |
<p>Consider an $X_i$, $Y_i$ distribution of points in a 2D plane. How can one assess if a given region in this 2D plane has a significant lack of points when comparing with the rest through a non-parametric test, without making any assumption on the underlying (unknown) distribution?</p>
<p>I would be tempted to mirro... | g359 | [
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0.018747860565781593,
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0.05061803758144379,
0.... |
<p>I am carrying out an MLE where some I use a log transformation on the variance parameters which are being optimized.</p>
<p>When I calculate the standard errors (se) the se of the transformed variables is massively too high!!!</p>
<p>There is a nice explanation of the delta method here:</p>
<p><a href="http://www... | g66130 | [
0.03836151212453842,
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0.04784523695707321,
0.07532911002635956,
0.0003... |
<p>I am trying to do a post-hoc test to make pairwise comparisons between slopes. I found a package called <code>phia</code> but is not available for the R version 2.13.2. Does anyone know if there is a similar package for this version of R?
Thanks!</p> | g3972 | [
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0.... |
<pre><code> Estimate Std. Error t value Pr(>|t|)
(Intercept) 10.2758 0.5185 19.817 < 2e-16 ***
rprice2 -1.8581 0.5139 -3.616 0.000696 ***
</code></pre>
<p>I would like to use the Std. Error of rprice2 to make other calculations. I know to reference any of the objects in the model,... | g49930 | [
-0.006212769541889429,
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-0.010145295411348343,
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0.06180518865585327,
0.09048309177160263,
0.0338... |
<p>I have large dataset (around 2 million records and 300 features) with a lot of missing data. Most of the independent variables are categorical (some of these variables have more than 40 valid values). The outcome is either Y or N. The Y outcome is a rare event: around 98% of outcomes are N. </p>
<p>I'm supposed to ... | g25029 | [
0.004136504605412483,
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0.0023761659394949675,
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0.0025273358915001154,
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0.037253912538290024,
0.008233313448727131,
-0.005543713457882404,
-0.025468559935688972,
0.012640786357223988,
0.04276087135076523,
... |
<p>From the <code>?rpart</code> documentation - </p>
<blockquote>
<p>na.action : the default action deletes all observations for which y is missing, but keeps those in which one or more predictors are
missing.</p>
</blockquote>
<p>How does it impute missing values in predictors?</p> | g66131 | [
0.06691336631774902,
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-0.011368324980139732,
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0.028261352330446243,
0.04905199259519577,
0.00... |
<p>I did the multiple linear regression on a dataset of 412 observations, with one response variable (Y) and 25 explanatory variables(X1-X25). Y and most of Xs are not normally distributed. Besides, there are some correlation between several Xs. The plot show that the residuals strongly correlated with Y positively and... | g25030 | [
0.05586995184421539,
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0.02483971230685711,
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-0.032666031271219254,
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0.0003984927898272872,
0.004665690008550882,
0.02... |
<p>I have carried out a simulation experiment where $n$ out of $N$ items $x_i$ were drawn with replacement with unequal probabilities $z_i$ from a finite population. (If it matters: $z_i = 1/(Nx_i)$ in my case, but perhaps there are more general results.)</p>
<p>Then, I estimated the population totals of the indicator... | g45251 | [
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0.0014607581542804837,
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0.03109315037727356,
-0.06112348660826683,
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-0.014033250510692596,
... |
<p>I applied the same hierarchical clustering (weighted) on two data sets: The first is a 'raw' data set, on which I didn't do anything, and the second on the same data set after I filtered it by removing some items I believe mislead the clustering. I computed the cophenetic correlation coefficients on both methods. Bu... | g66132 | [
0.05549011379480362,
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0.021967900916934013,
0.03948059305548668,
0.01... |
<p>I am working on a project in which I am trying to identify mentions of car makes and models in forum posts. I would like to say what I have tried so far and then ask for any feedback or suggestions of other approaches. So far I have tried two approaches - a named entity recognition method, and a dictionary-based m... | g66133 | [
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0.03160173073410988,
0.03528308495879173,
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0.02666836977005005,
0.05195245146751404,
-0.058160003274679184,
0.06817026436328888,
0.0... |
<p>I am trying to run a multiple regression in SPSS.</p>
<p>I am using panel data with 4 independent variables. Of these, one is a dummy variable.</p>
<p>Can someone please guide me through the process or give me some hints since I'm a beginner in this.</p>
<p>I have 350 companies. These companies have a "score" (de... | g66134 | [
0.010829320177435875,
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0.005331065971404314,
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-0.030955594033002853,
0.03815412521362305,
-0.013635586015880108,
... |
<p>I have $n$, $p$-dimensional vectors and I am constructing the $p \times p$ covariance matrix using the following formula:</p>
<p>$$\mathrm{Cov}(j,k) = \frac{1}{n-1} {\sum^n_{i=1}} (x_i(j) - {\mu}(j))(x_i(k) - {\mu(k)}) $$</p>
<p>However, the values in the $p$-dimensional vectors are between 0 and 1, as it is a n... | g66135 | [
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0.013441268354654312,
0.025928178802132607,
... |
<p>I have a two heavily <strong>skewed</strong> distributions and am trying to use <strong>bootstrapping</strong> to compare their means via the <strong>t-test</strong>.</p>
<p>I am concerned about the appropriateness of using the standard error of the original/observed data in the final step when I know that this is ... | g66136 | [
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0.02145129069685936,
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0.022368406876921654,
0.04260854795575142,
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0.05580572411417961,
0... |
<p>I need an idea for a new rating system.. the problem in the ordinary one (just average votes) is that it does not count how many votes... </p>
<p>For example consider these 2 cases:</p>
<p>3 people voted 5/5</p>
<p>500 people voted 4/5</p>
<p>The ordinary voting systems just take the average, leading to the firs... | g29296 | [
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0.023280330002307892,
0.02318532019853592,
0.0239733774214983,
0.01215825043618679,
0.0201... |
<p>I am collecting papers about the uniform shrinkage prior for hierarchical Bayesian model.
In <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.56.1224&rep=rep1&type=pdf" rel="nofollow">"A prior for the variance in hierarchical models"</a> of Michael J. Daniels it is stated at the end of page ... | g66137 | [
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0.013272077776491642,
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0.039792437106370926,
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... |
<p>I am doing some multiple regression using R's <code>lm()</code> method. I wonder whether there is an easy way to limit the impact of some predictors. I think <code>lm()</code> results give too much weight to certain predictors and I would like to somehow cap coefficients of certain predictors. Is it doable?</p> | g66138 | [
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0.02163701318204403,
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0.05752589553594589,
0.02... |
<p>I would like to sample from:
$$
p(\theta_2|x)=\int p(\theta_2|\theta_1,x) . p(\theta_1|x) . d\theta_1
$$</p>
<p>Several persons suggest me to use the following procedure to draw $(\theta_2^i)_{i=1:N}$:</p>
<pre><code>for i=1:N
draw $\theta_1^i$ from $p(\theta_1|x)$
draw $\theta_2^i$ from $p(\theta_2|\theta... | g66139 | [
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0.029376789927482605,
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-0.00659332238137722,
0.045732054859399796,
0.013775634579360485,
0.01686127483844757,
... |
<p>I am building a Logistic regression model for a churn problem. When I scored the out of sample data set, I find very low probability levels as the output probability. Conventionally, I would look for .5 as the cut off but this scored population doesnt have many customers above .5 ( say just 1%). Seeing the business ... | g37425 | [
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0.021213343366980553,
0.019376568496227264,
0.04860217124223709,
-0.0066... |
<p>Suppose products A, B and C are sold on markets 1, 2 and 3.
I have access to three years worth of monthly historical data.
I'd like to detect/foresee possible shifts in sales mix for the three products over the three markets (e.g. I'd like to know if market 1 is buying more of product A than it used to, or if produc... | g25037 | [
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0.015750285238027573,
-0.0031533685978502035,
0.018593033775687218,
0.035917170345783234,
... |
<p>Suppose we have a categorical variable $X_1$ with $100$ levels. Should we <strong>not</strong> test interaction between $X$ and some other variable $X_2$? </p>
<p>Because if, for example, $X_1(3)*X_2$ is not significant then the interaction between $X_1$ and $X_2$ is not significant?</p> | g66140 | [
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0.011344755999743938,
-0.0226810406893491... |
<p>Using R, I have fitted a linear model for a single response variable from a mix of continuous and discrete predictors. This is uber-basic, but I'm having trouble grasping how a coefficient for a discrete factor works. </p>
<p><strong>Concept:</strong> Obviously, the coefficient of the continuous variable 'x' is app... | g45255 | [
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0.01378360390663147,
0.05689842998981476,
-0.04... |
<p>i have time series data (download at:-->http://www.4shared.com/rar/ft3YCN2H/Time_series_data.html)</p>
<p>consider potential values as time series data points(4th column)</p>
<p><code>file<-read.table(filename.txt,skip=1)</code>
<code>ts_data<-file$V4 #final time seris vetor</code></p>
<p>please,<strong>gi... | g66141 | [
0.02858872525393963,
-0.06342903524637222,
-0.028564568608999252,
-0.00744412187486887,
-0.0008987693581730127,
-0.05106654763221741,
0.005779596511274576,
-0.0015888178022578359,
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0.00945446826517582,
0.05949278548359871,
-0.00011227100185351446,
0.07696784287691116,
... |
<p>Hi and thanks for any help re the below</p>
<p>This is a fairly complex question so I will attempt to ask it in a fairly basic manor. </p>
<p>I have data on the abundance of 99 different species of estuarine macroinvertebrate species and the sediment mud content (0 - 100 %) in which each observation was obtained. ... | g49742 | [
0.008273421786725521,
-0.004560567904263735,
-0.000586514244787395,
-0.0642557144165039,
0.022588739171624184,
-0.0020062404219061136,
-0.01203157939016819,
0.003847279818728566,
-0.023182159289717674,
0.006103491876274347,
0.010868372395634651,
-0.015319324098527431,
0.08032063394784927,
... |
<p>I need to analyze with R the data from a medical survey (with 100+ coded columns) that comes in a CSV. I will use <a href="http://rattle.togaware.com/" rel="nofollow">rattle</a> for some initial analysis but behind the scenes it's still R.</p>
<p>If I <em>read.csv()</em> the file, columns with numerical codes are t... | g45258 | [
-0.0005557717522606254,
-0.010702957399189472,
0.003951955121010542,
-0.09294575452804565,
0.05446041747927666,
-0.04572984203696251,
0.017983635887503624,
0.030044592916965485,
-0.08819921314716339,
0.0018635158194229007,
0.0022239824756979942,
-0.012184517458081245,
0.06316977739334106,
... |
<p>I am controlling for education-level (two dummy variables) and another covariate in my regression model. I'm conducting a hierarchical regression analysis. I was confused about how I should be entering all the predictors. Do I enter the dummy variables and other covariate in the first block and then the main predict... | g66142 | [
0.025406591594219208,
-0.012926007620990276,
0.007054747082293034,
-0.04373748600482941,
0.037414371967315674,
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0.053771715611219406,
0.02548040822148323,
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-0.019893689081072807,
-0.020070379599928856,
0.06012922525405884,
-0.005199067294597626,
0... |
<p>In the case of count data where my variance is 6.34 and mean is 5.44, which would be a better fit to the data - Poisson or negative binomial? And what will be the assumptions ?</p> | g66143 | [
0.0507236085832119,
0.019567154347896576,
-0.003919186070561409,
0.00730384886264801,
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0.00918512511998415,
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-0.03466634824872017,
-0.05421963706612587,
0.0005106860189698637,
-0.03301083296537399,
-0.06772971153259277,
-0.0... |
<p>I want to cluster ~22000 points. Many clustering algorithms work better with higher quality initial guesses. What tools exist that can give me a good idea of the rough shape of the data?</p>
<p>I do want to be able to choose my own distance metric, so a program I can feed a list of pairwise distances to would be ju... | g66144 | [
0.018319951370358467,
-0.011313856579363346,
-0.013601154088973999,
-0.005477049853652716,
-0.053693823516368866,
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-0.005793314892798662,
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-0.021493986248970032,
0.023367678746581078,
0.03699059784412384,
0.12316405773162842,
... |
<p>I have a time-series of daily measurements of some quantity for 1995-2011. There's about one measurement every three days.</p>
<p>The data show a strong seasonality (annual cycle).</p>
<p>What I ultimately want is get an estimation for the underlying trend. <a href="http://www.jos.nu/Articles/abstract.asp?article=... | g45261 | [
0.006014603190124035,
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0.02347167395055294,
0.015631914138793945,
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0.007451833691447973,
0.009169643744826317,
0.06403423845767975,
0.... |
<p>I am trying to write unit tests for a whole mess of statistics code. Some of the unit tests take the form: generate a sample following a null hypothesis, use code to get a p-value under that null, repeat hundreds of times, then look at all the p-values: if they are reasonably uniform, then the code passes. I usually... | g66145 | [
0.0043213400058448315,
-0.04082607105374336,
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-0.056997545063495636,
0.020354781299829483,
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-0.012217528186738491,
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0.026048362255096436,
0.03400516137480736,
... |
<p>I just read an interesting article on how Target used purchase behavior as a predictor to whether they were pregnant or not. <a href="http://www.forbes.com/sites/kashmirhill/2012/02/16/how-target-figured-out-a-teen-girl-was-pregnant-before-her-father-did/" rel="nofollow">Here's the link</a>. </p>
<p>Could someone ... | g66146 | [
-0.03655800595879555,
0.013619552366435528,
-0.0028329796623438597,
0.03414471447467804,
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0.030061736702919006,
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-0.04013669118285179,
-0.02263018488883972,
-0.02648540772497654,
0.09851577877998352,
... |
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