question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have a continuous variable $y$. Using univariate linear regression I have tested $a, b$ and $c$ as independent variables against $y$ as a dependent variable.</p>
<p>I have gotten different $R^2$ and $p$-values.</p>
<ul>
<li>$Y + a: R^2 = 0.60, p < 0.01$</li>
<li>$Y + b: R^2 = 0.20, p < 0.04$</li>
<li>$Y + ... | g61116 | [
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<p>I'm trying to analyze the intra-rater reliability of an occupational therapy assessment.</p>
<p>The assessment consists of 57 items, where some items are ratio data and some items are ordinal data.
In my study 31 raters rated 4 subjects (on video) twice (time 1 and time 2) with a six week interval.
So I have scores... | g61117 | [
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<p>Here's my understanding of the kernel trick. The motivation is to find a linear separator in a higher dimensional space than what you have (because the data are not currently linearly separable.) You take the dot product, and then apply the transformation to the result, saving you the time of applying the transfor... | g61118 | [
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<p>I have two functions that provide an implementation of the t-distribution.</p>
<p>A webpage with a <a href="http://www.math.ucla.edu/~tom/distributions/tDist.html" rel="nofollow">Javascript algorithm</a>. The algorithm takes two input <strong><code>x-value</code></strong> and <code>degrees_of_freedom</code>.</p>
<... | g61119 | [
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<p>I am trying to use R to predict the absolute risk of developing adverse events in a cohort, and to compare that with the observed outcome. Should I use <code>survreg</code> or <code>coxph</code> to do this? Anyone kind enough to explain how to do this with R code? </p>
<p>The mean follow up period of my cohort is o... | g61120 | [
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<p>Sorry about the noob question, we tried looking through the answers but couldn't make sense of it. We are very basic with our math/stat knowledge, so please bear with us if this makes less relevant sense.</p>
<p>We have a data set - For example sake - scores (out of 100) in <em>N</em> Subjects for 800 students. </p... | g17571 | [
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<p>I need to calculate the log-likelihood for a linear regression model in MATLAB. </p>
<p>Although the theoretical result is well know and given in several sources, I want to find a numerical example so that I can check my code is correct.</p>
<p>Can anyone point me to one?</p>
<p>I realize that the parameters are ... | g61121 | [
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<p>I have two data sets, A and B. Both have a large number of continuous variables. I believe that A is related to B. But there are no defined classes in either A or B. I could do a bunch of correlation tests to see if any of the variables in A are strongly correlated with B. But many variables in A are likely dependen... | g17572 | [
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<p>I am measuring for the existence of response in cell signal measurements. What I did was first apply a smoothing algorithm (Hanning) to the time series of data, then detect peaks. What I get is this:
<img src="http://i.stack.imgur.com/3bAEP.png" alt="time series of cell signal response"></p>
<p>If I wanted to make ... | g47299 | [
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<p>I'm working in R through an excellent <a href="http://www.cs.otago.ac.nz/cosc453/student_tutorials/principal_components.pdf" rel="nofollow">PCA tutorial by Lindsay I Smith</a> and am getting stuck in the last stage. The R script below takes us up to the stage (on p.19) where the original data is being reconstructed... | g61122 | [
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<p>For a classification project we are using the randomForest package in R, which wraps the <a href="http://www.stat.berkeley.edu/~breiman/RandomForests/cc_home.htm" rel="nofollow">Breiman</a> Fortran random forest implementation, to assess the importance of each of our features. I would like to calculate p-values for ... | g61123 | [
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<p><strong>Disclaimer:</strong>
<em>this is directly related to a homework problem. The example I am giving is based off the homework problem (because I am more interested in how to solve it than in what the answer is).</em></p>
<p><strong>Data given:</strong></p>
<ul>
<li>Number of people surveyed: 50</li>
<li>Sum ... | g47302 | [
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<p>Note: I'm not even sure how to best title this question, so if anyone has any ideas, please edit!</p>
<p>Consider six independent draws from a distribution defined by a cdf $F(x)$ over 0-1. Let’s call them $X1, X2 . . . X6$.
I want to define the distribution for X1+X3, if I know the following information:</p>
<u... | g535 | [
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<p>I am having a problem with the <em>random</em> term in <code>lme</code> and <code>lmer</code>. In a repeated measures setting, we usually have the following variables: <code>id</code>, <code>response</code>, <code>factor(s)</code> and <code>time</code>. I've seen <code>random = ~ 1 | id</code>, <code>random = ~ time... | g49613 | [
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<p>Let's say I have 100 parts. I sample one part and find it defective. I then sample another five parts and do <em>not</em> find them defective. What statistical procedure would I use that combines this information to provide a confidence interval or failure rate?</p> | g61124 | [
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<p>Sorry to keep bothering you guys with this thing, but another stupid question: Given the following data (from my previous <a href="http://stats.stackexchange.com/questions/13352/how-do-you-deal-with-a-multiple-choice-observation-in-bayesian-inference-when/13363#13363">question</a>), how would one calculate the cond... | g61125 | [
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<p>I have used <code>rpart.control</code> for <code>minsplit=2</code>, and got the following results from <code>rpart()</code> function. In order to avoid overfitting the data, do I need to use splits 3 or splits 7? Shouldn't I use splits 7? Please let me know.</p>
<p>Variables actually used in tree construction: </p>... | g47308 | [
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<p>I am using stratified sampling and neyman's optimal allocation to compute the best sample size for each stratum. neyman's optimal allocation is given by the formula,</p>
<p>$$n_h = n \frac{N_h * S_h}{\sum_i N_i * S_i}$$</p>
<p>where $$\sum_h n_h = n$$ $$\sum_i N_i = N$$</p>
<p>and $n$ is the total sample size, $n... | g61126 | [
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<p>I have germination data in percentages (with a few zeros) and wish to fit a GLM on them to explore how different seed origins and levels of treatment affect them.</p>
<p>My results are not exactly 'counts', but is it ok to use Poisson family (ultimately quasi-poisson)? </p>
<p>I don't want to transform them to pro... | g61127 | [
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<p>Using R, I have developed three models: </p>
<ul>
<li>linear regression using <code>lm()</code>;</li>
<li>decision tree using <code>rpart()</code>;</li>
<li>k-nearest neighbor using <code>kknn()</code>. </li>
</ul>
<p>I would like to conduct leave-one-out cross-validation tests and compare these models. However, ... | g47312 | [
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<p>Let us say I have the following pair wise test data:</p>
<pre><code>batch 1 2 3 4 5 6 7 8 10
non-control 18 16 15 19 36 24 25 30 31
control 20 23 25 19 28 24 26 21 22
</code></pre>
<p>Each data point is measurement of some attribute X in some units</p>
<p>The ... | g61128 | [
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<p>I have Training data like following :</p>
<p>1 1:128.319 2:71.4336 3:130.255 4:292.948 5:96.3541 6:71.942 7:136.189 8:71.5032 9:148.21 10:304.011 11:90.3781 12:99.4496 13:164.268 14:138.892 15:220.871 16:139.198 17:151.709</p>
<p>1 1:118.431 2:97.5874 3:92.0313 4:242.383 5:32.5916 6:91.4476 7:122.88 8:86.6046 9:10... | g61129 | [
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<p>Suppose I wanted to test for a difference in BOTH the mean and variance, how would I go about constructing a test statistic for this purpose? <br><br> I suppose my null hypothesis would be that the mean and variance in one population are the same as the mean and variance in another, whilst the alternative hypothesis... | g61130 | [
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<p>Cases and observations.</p>
<p>It is my understanding that sample size is determined by the number of individuals taking part in an experiment (from my undergrad Psychology stats course). For each individual a mean is calculated from the result of each trial. These means are entered as data in SPSS. The mantra of t... | g61131 | [
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<p>I am doing multivariate analysis using logistic regression to see the relationship between one categorical outcome variable and a group of continuous and categorical explanatory variables. I did preliminary explanatory analysis using chi-square for the categorical covariates and t-tests and Mann-Whitney tests for th... | g61132 | [
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<p>I am currently working on a simulation study in which I compare two methods for analysing data from a repeated measures design. Let's say there are n subjects, and each subject goes through i conditions of the experiment. In each condition, there are j trials. So for each subject, I have i*j values. Since the data I... | g17582 | [
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<p>I'm using both nltk NaiveBayesClassifier and SklearnClassifier for classification of sentences. Is there is a way to find which is the best classification. For eg: If i give "You are looking not so great" , one is classifying it as "Positive" and other as "Negative". I just want to know which is correct or which is ... | g61133 | [
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<p>I have to group $A$ ($\bar X_1 =20, N_1=10$) and group $B$ ($\bar X_2 = 25, N_2=15$). Is there a way I can compare these two groups and get some statistical significance? I was thinking about using the $t$-test, but the standard deviation is not provided.</p> | g17588 | [
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<p>I have read the <a href="http://en.wikipedia.org/wiki/Weighted_arithmetic_mean" rel="nofollow">Wikipedia article</a>, and know that the unbiased weighted sample covariance matrix for the row vector $\mathbf{x}_i$ is $$\Sigma=\frac{1}{\sum_{i=1}^{N}w_i - 1}\sum_{i=1}^N w_i \left(\mathbf{x}_i - \mu^*\right)^T\left(\ma... | g61134 | [
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<p>I am reading the book related to SEM (Byrne, 1998) and it is stated that regression of the observed variables on the factor, and the variances of both the errors of measurement and the factor, as well the error covariance, are of primary interest. Why is error variance important in CFA, and particularly error covari... | g17589 | [
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0.03... |
<p>For my research question, I want to find out if two different group types (IV) vary across position categories (DV) for eight different limbs. My data is nominal, so I'll be testing this by doing 8 chi square/Fisher's exact tests, one for each limb. For example, the group <em>x</em> lower leg contingency table is a ... | g61135 | [
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<p>I want to predict whether a loan is default or fully paid, with about 20 features and 10,000 historical observations.</p>
<p>Among the data over 85% are fully paid, 15% are default, I want to try classification tree, but it won't split. Do I have to balance the outcome first? That is to say, I randomly sample 1500 ... | g61136 | [
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<p>I read <a href="http://www.evanmiller.org/how-not-to-run-an-ab-test.html" rel="nofollow">this article</a> on "how not to run an A/B test".</p>
<p>And I still don't understand what exactly the author's reasoning is. Can someone dumb it down for me?</p>
<p>I think what it might be saying is that reading the results ... | g61137 | [
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<p>I have two continuous variables, X and Y, that are correlated - they are not independent. To correct for non-independence, I have a known correlation structure, a matrix S.</p>
<p>If one calls <code>gls(Y ~ X, correlation = S)</code>, what I think happens is that, internally, gls() transforms X and Y in some way so... | g43445 | [
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<p>We ask a set of users to independently detect and annotate all the buildings on a map.
We do not have a priori knowledge about the location or event the existence of buildings on this map.</p>
<p>I would like to aggregate/cluster their annotations in a way that only 'consensual' annotations are taking into account.... | g17593 | [
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<p>I am working to investigate association between environmental pollution and daily hospital admission due to various causes. This outcome data has excess zeros on days when there are no admissions for specific causes. I would like to adjust for temperature and humidity using smooth terms. Usually Poisson generali... | g61138 | [
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<p>This question might be very basic, but yet it makes me wonder, so I wanted to ask you for an opinion.</p>
<p>How much calculation is allowed or desired when creating a variable? Are there at all any limitations? Is it perhaps desired to "mess" with data as little as possible and use it in its purest form?</p>
<p>F... | g17595 | [
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<p>In this <a href="http://www.casact.org/pubs/proceed/proceed97/97553.pdf" rel="nofollow">paper</a>, Kreps studies the effect of sample size on parameter estimates in normal and lognormal distributions. Three methods are studied: 1) infinite, 2) approximate, and 3) effective. The idea is that in reinsurance industry, ... | g17596 | [
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<p>Can anyone help give a conceptual explanation to how predictions are made for new data when using smooths /splines for a predictive model? For example, given a model created using <code>gamboost</code> in the <code>mboost</code> package in R, with p-splines, how are predictions for new data made? What is used from t... | g61139 | [
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<p>I got a little confused with the squares and the sums. As far as I know, the variance or total sum of squares (TSS) is smth like</p>
<p>$\sum_{i}^{n} (x_i - \bar x)^2$</p>
<p>and the sum of squares within (SSW) is</p>
<p>$\sum_{j}^{K} \sum_{i}^{n} (x_i - c_j)^2 \qquad i \in C_j$ where k ist the number of clusters... | g61140 | [
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<p>The following is a worked example found in past papers of my university, but haven't been able to figure out to solve it (I have the answer, but do not understand how to get there). Any help in enlightening me would be much appreciated.</p>
<p>A store sells on average four computers a day. Once every fourteen days ... | g792 | [
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<p>I am trying to compare differences in sites and years related to the environmental variables. For example, is there a significant difference in chlorophyll concentration (chlo) over the years (from 2002-08)? Or is there a difference in chlorophyll concentration between Seychelles, Indonesia and Brazil? I have starte... | g61141 | [
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<p>Dose anybody know's what creating Laplacian Graph from similarity matrix brings us in spectral clustering ? or why we create it ?
Here it's the Algorithm:
Laplacian graph is : <strong>L= D-W.</strong> ,<strong>D:</strong> degree matrix of similarity graph, <strong>W=</strong> weighted adjacency matrix </p>
<p><img... | g61142 | [
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<p>I have 400 responses to a 20 item questionnaire which purports to measure an attitudinal constuct in medical students. The instrument was validated in the US for a single year of medical students and the published data is very "clean"- all ritc values >0.3,alpha 0.84, PCA with a stable four factor structure etc. In ... | g17602 | [
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<p>$X$ and $Y \sim U(0,1)$.</p>
<p>Let $$\eqalign{
g(x,y) &= x &\text{ if } &x^2+y^2 \le 1 \\
&=2 &\text{ if } &x^2+y^2 \gt 1
}$$</p>
<p>and $Z = g(X,Y)$. How to find $F_Z(z), \mathbb{E}(Z)$, and $\mathbb{E}(Z | X^2+Y^2 \gt 1 )$?</p>
<p>I would appreciate your help.</p> | g61143 | [
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<p>What is the correct way to fit a multiple regression model where I have a combination of cubic and linearly related independent variables?</p>
<p>If I transform the variable showing cubic relationship, how do I transform back the forecasted variable, given that it's the result of both non-transformed and transforme... | g17609 | [
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<p>Are there any tools in R that could be used to optimize the allocation of customers amongst possible offers, given constraints? Can anyone give hints/examples on their use? Hope my setup makes sense...</p>
<p>Here is the problem setup:</p>
<p><strong>There are the following:</strong></p>
<ul>
<li>$N$ customers ($... | g61144 | [
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<p>I have the following model:</p>
<p>$$ y_{i} = \alpha + \beta{d_{i}} + X^{'}_{i}\gamma + \epsilon_{i} $$</p>
<p>Where $d_{i}$ is a dummy variable and $X^{'}_{i}$ is a vector of control variables. I want to estimate the the causal effect of $d_{i}$. Suppose that the regression is saturated in $X_{i}$ so that $E(d_{i... | g28177 | [
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<p>I have some data that look like:
<img src="http://i.stack.imgur.com/fBXQM.jpg" alt="enter image description here">
These data show between case (spinal cord injury) and control the number of drugs that patients in these populations were prescribed at any given time. I'm looking for a p-value to determine that the ... | g61145 | [
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0.000996... |
<p>I was wondering if there is a package I can use to convert my 22 annual observations to quarterly series?</p>
<p>Will there be any harm in doing so? Will I lose any important data specific information? I want to run VARs in levels using TY method.</p> | g22114 | [
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<p>I need to calculate a permutation-based p-value with significance level $\alpha$, how many permutations do I need ?</p>
<p>From the article <a href="http://jmlr.org/papers/volume11/ojala10a/ojala10a.pdf" rel="nofollow">"Permutation Tests for Studying Classifier Performance"</a>, page 5 :</p>
<blockquote>
<p>"In ... | g61146 | [
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0.0369... |
<p>Is there a package that includes a likelihood ratio test for time series data with an unknown number of breaks in R? My search wasn't very successful, yet...</p> | g17619 | [
0.0034700045362114906,
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<p>What are the assumptions for the proper use and interpretation of the Pearson's correlation coefficient? </p>
<p>How is $\DeclareMathOperator{\cov}{cov}\cov(X,Y)$ affected by (mild) deviations of linearity? </p>
<p>How is $\cov(X,Y)$ influenced by the presence of heteroscedasticity?</p> | g47332 | [
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<blockquote>
<p>The lifetime of a machine is modelled by an exponential random variable $X$ with $P(X>x) = e^{-\lambda x}, \lambda, x > 0$. This machine cannot be repaired. A maintenance crew checks this machine at times $T, 2T, 3T, ...., $ where $T$ is a specified length of time</p>
<p>Consider the events... | g61147 | [
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<p>I have 1 categorical factor (3 treatments) and 1 continuous factor (weight) and then I have 5 continuous response variables.</p>
<p>From what I have read, I should not use a two way ANOVA as one of the factors is continuous. Is this correct? Should I be using a Multiple Regression instead?</p>
<p>I was advised th... | g61148 | [
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<p>Is there a difference between the two uses of 95% in:</p>
<ul>
<li>mean + 2 standard deviations (statistically significant)</li>
<li>confidence interval</li>
</ul> | g15920 | [
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<p>The "proof" in my textbook was very short and only in the discrete case, I didn't understand it very well too. So I tried to derive the expression starting from the expected value of a continuous random variable. I started by letting the variable be a function of another variable but then I got stuck trying to chang... | g17627 | [
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<p>I have a variable X1 = (a - b) / (a + b). This variable shows a higher correlation to Y that any of (a, Y) and (b, Y).</p>
<p>In a multiple regression model like Y ~ X1, X2, does it make sense to use the X1 formula, or should I always use the base variables a and b?</p>
<p>In <a href="http://stats.stackexchange.co... | g61149 | [
0.03699532523751259,
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0.03594853729009628,
0.023945961147546768,
0.0496838353574276,
0.0249... |
<p>I've been reading the following (great!) book <a href="http://www.inference.phy.cam.ac.uk/itila/" rel="nofollow">http://www.inference.phy.cam.ac.uk/itila/</a>, which has sparked some questions about MLE.</p>
<p>I'm comfortable with the notion that ML estimators are often biased.</p>
<p>However, I was very curious ... | g61150 | [
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... |
<p>Concerning the <a href="http://en.wikipedia.org/wiki/Pearson%27s_chi-squared_test" rel="nofollow">Pearson chi-square test</a> there seems to be a subtle difference between the goodness-of-fit test and the test of independence.</p>
<p>What is confusing is that both tests seem to be calculated in a very similar way.<... | g61151 | [
0.024792496114969254,
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<p>I am new to statistics, so pardon any mistakes in my question.</p>
<p>I have two time series $X_i$ and $Y_i$. Assuming that they're stationary AR(1) processes with possibly different means, how do I test for difference of means?</p>
<p>I found this link (but tests only one sample) which discusses using gls: <a hre... | g17631 | [
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<p>I have an experiment producing results (dependent variables) that don't pass tests of normality, thus I am testing hypotheses using non-parametric tests.
My DVs are continuous, while my factors (independent variables) are ordinal or nominal.
I've been using the Kruskal-Wallis test and Friedman test (using Matlab).
M... | g61152 | [
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... |
<p>I'd like to use Simple Exponential smoothing to forecast the lead-time demand for inventory
control, I have monthly data and LT+1 is equal to 5 months, can I do a forecast using SES which gives me a one-period-ahead forecast and then multiply it by 5 to get the forecast for LT+1 ?
what is the best solution to get h... | g546 | [
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0... |
<p>I do not understand the persp plot, my example is:</p>
<pre><code>c<-mat.or.vec(5,2)
c[1,1]<-1
c[1,2]<-1
c[2,1]<-1
c[2,2]<-1
c[3,1]<-2
c[3,2]<-0
c[4,1]<-1
c[4,2]<-1
c[5,1]<-1
c[5,2]<-1
persp(c,xlab = "X", theta = -60,ylab = "Y", zlab = "Z",ticktype = "detailed"
)
</code></pre>
<p>... | g17634 | [
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0.04837200045585632,
-0.015725... |
<p>Say I have some data for past 5 years and I have trained my classifier (anything decision tree, svm etc.) based on that i.e. given the appropriate input feature data and correct output labeling.</p>
<p>Now for current year when I have to make prediction (predicting the output) I can supply the input feature data I ... | g61153 | [
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0.01968... |
<p>I have data with many correlated features, and I want to start by reducing the features with a smooth basis function, before running an LDA.</p>
<p>I'm trying to use natural cubic splines in the <code>splines</code> package with the <code>ns</code> function. How do I go about assigning the knots?</p>
<p>Here's th... | g61154 | [
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0.03213508799672127,
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0.023772... |
<p>Linear model in matrix form is</p>
<p>$
\mathbf{y}=\mathbf{X}\beta+\epsilon\textrm{ where }\epsilon\sim\mathbb{N}\left(0,\sigma^{2}\mathbf{V}\right).
$</p>
<p>Then $\beta$ can be estimated through generalized least squares
as</p>
<p>$
\widetilde{\beta}=\left(\mathbf{X}^{\prime}\mathbf{V}^{-1}\mathbf{X}\right)\mat... | g61155 | [
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0.015207549557089806,
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0.05774817615747452,
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0... |
<p>Per my <a href="http://stats.stackexchange.com/q/7115/1026">earlier question</a> I'm trying to find a reasonable metric for the semantic distance between two short text strings. One metric mentioned in the answers of that question was to use shortest hypernym path to create a metric for phrases. So for instance, i... | g61156 | [
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0.034437648952007294,
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0.03973458334803581,
-0.0... |
<p>In SPSS linear mixed model (analyze->mixed model->linear), one can opt for predicted values. In the SPSS data file, a column is added with new data, i.e., the predicted values. When I run a linear model via generalized linear mixed model in SPSS (analyze->mixed model->generalized linear, which is basically the same ... | g61157 | [
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... |
<h2>Background</h2>
<p>Conventional approaches to fitting a priori models to observed data seek to find those model parameters that maximize the likelihood of the data. For more complicated models, this typically necessitates an iterative search across a reasonable parameter space, computing the likelihood of the data... | g61158 | [
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0.03588235750794411,
0.03682556375861168,
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0.030900588259100914,
0.06... |
<p>Why bucketing of continuous variables is preferred in logistic regression ? What is the funda behind adjusted log odds ratio and unadjusted log odds ratio when we have a continuous variable ?</p> | g47345 | [
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0.036916013807058334,
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0.0197769608348608,
0.0... |
<ol>
<li><p>From Casella's Statistical Inference:</p>
<blockquote>
<p>Definition 10.1.7 For an estimator $T_n$, if $\lim_{n\to \infty} k_n Var T_n = \tau^2 < \infty$, where $\{k_n\}$ is a sequence of
constants, then $\tau^2$ is called <strong>the limiting variance</strong> or
<strong>limit of the variances</s... | g361 | [
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0.00810311734676361,
... |
<p>The "exclusive or" function has a long and arduous history in the AI/machine learning communities. From my understanding of "association rule learning", xor would appear to be a problem for this type of learning. That is, suppose we have the following data:</p>
<pre><code>A B C
0 0 0
0 1 1
1 ... | g61159 | [
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0.017088117077946663,
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0.03915229067206383,
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0.00897367112338543,
0.03615492582321167,
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-0.007786743342876434,
0.04045676440000534,
0.0194135420024395,
0.04989398643374443,
0.0332388... |
<p>I have an explanatory variable, <code>close</code>, which is the daily close price of a firm in the stock market.</p>
<p>The following summarizes this explanatory variable:</p>
<pre><code> quote at market close
-------------------------------------------------------------
Percentiles ... | g61160 | [
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0.025512132793664932,
0.033782459795475006,
0.03097257763147354,
0.03260420262813568,
... |
<p>Let we have data of 3D (example angular velocity x, angular velocity y, angular velocity z).Can anyone explain/give example/how to differentiate between gaussian distribution and non-gaussian distribution of data since the difference is important for us to make decision whether to use Kalman filter or particle filte... | g47347 | [
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0.08391629159450531,
-0.0299... |
<p>Take a linear model with a block random effect ($b_i$)
$$
y_{ij} = \mu + b_i + \beta x_{ij} + e_{ij}
$$
with $b_i \sim N(0, \sigma_b^2)$, etc etc.</p>
<p>If $\sigma^2_b = 0$, then the model reduces to a very simple linear model. To test the null hypothesis $H_0: \sigma_b^2 = 0$ versus the alternative $H_1: \sigma_... | g61161 | [
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0.0037182457745075226,
0.02775459922850132,
0.009911994449794292... |
<p>Could you please advise whether studentized residuals are meaningful when computed on a robust linear regression model using an M-estimator? </p>
<p>I'd like to use it to detect outliers by doing something like this:</p>
<pre><code>rfit = rlm(y~x, data=d)
pt(rstudent(rfit), df=nrow(d)-3)
</code></pre>
<p>Is this... | g61162 | [
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... |
<p>This question follows up my <a href="http://stats.stackexchange.com/questions/59107/logistic-regression-controlling-variables-not-significant-what-should-i-conclu">first one</a>.</p>
<p>I ran logistic regressions on a period of a few years. The authors that created the model I'm using aggregated their yearly result... | g61163 | [
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0.0013808676740154624,
0.1000920832157135,
... |
<p>I'm plotting the following point using python (a and b have are non gaussian):</p>
<pre><code> x=np.log10(a)
y=np.log10(b)
xmedian=np.median(x)
ymedian=np.median(y)
</code></pre>
<p>and I need to add errorbars on the y from percentiles so I wrote (n is the number of points):</p>
<pre><code> y1=np.percentile(y,... | g38119 | [
-0.03357790783047676,
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0.009634959511458874,
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0.003855830291286111,
0.045271847397089005,
0.03571666404604912,
0.04... |
<p>I've seen the concept of regret apply mostly to online learning problems, but while going through the definition it does seem that is not bounded to this setting.</p>
<p>I'm trying to come with a simple example to explain this concept in terms of simple linear models.</p>
<p>The Wikipedia page does try to do it, b... | g61164 | [
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<p>I am trying to fit an ARMA(p,q) model to the mean equation of my return series. The problem is, that the acf and pacf are pretty not usable, i.e. it is hard to find a good model to take account of the acf and pacf pattern. I am aware of the alternative of using no model at all for the mean equation.</p>
<p>Neverthe... | g61165 | [
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0.047611601650714874,
-0.019... |
<p>I'm doing linear regressions where the dependent variable is a ratio that can range from 0.01 to 100.</p>
<p>Is it ok to take the log of the dependent variable and the regression on that?
I'm matching the results of a study and that is what they did.</p>
<p>What is the difference of taking the log versus using the... | g61166 | [
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0.00897147785872221,
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<p>I did numerical simulations of two different systems that returned me N=1000 histograms expressed as $\{x,y,y'\}$, where $x$ is the independent variable, $y=P(x)$ is the probability distribution (frequency of x), $y'=P_0(x)$ is the theoretical probability which is a Chi-Squared Distribuion with parameter one (this i... | g231 | [
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0.03309242054820061,
0.016... |
<p>I'm reading Florens et al.'s 'Elements of Bayesian Statistics', currently working through chapter 1, 'Reduction of Bayesian Experiments'. I find most of it clear, except the definition of regular conditional experiments (p. 51) and everything that relies on this definition. I'll appreciate help in deciphering it. I ... | g61167 | [
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... |
<p>I have multiple years of daily aggregated data for which I want to conduct a multi-variable linear regression. Auto correlation is high with one particular variable included and there is a strong physical relationship for this to be the case. In my case I wish to minimize this effect by aggregating to a weekly lev... | g61168 | [
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0.01707991026341915,
0.06675956398248672,
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0.051790423691272736,
0.00... |
<p>Suppose there is a matrix A with m rows and n columns. Each element is a 3 dimensional vector. This 3 dimensional vector have values of different orders. Can we calculate covariance of such matrix ?</p> | g3676 | [
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... |
<p>Suppose, I do a experiment where I have an event 'a' true 1000 times in 1000 trials. So, the probability becomes 1000/1000 = 1.
If I am going to do another trial, my prediction about event 'a's occurrence is 1.</p>
<p><strong>Is there a way to factor in the calculation of probability the fact that I am not done wit... | g17645 | [
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0.0167066790163517,
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0.0381... |
<p>Typically, in Bayesian bootstrap, you have samples {$x_1,...,x_n$} of a random variable $X$.
Choose $\{p_1,...,p_n\}$ from a Dirichlet distribution, by sorting $\{0,1,u_1,...,u_{n-1}\}$ where $u_i$ are independent samples from $U \sim Uniform(0,1)$, and taking differences of sorted neighbors.
Use $\{p_1,...,p_n\}$ a... | g61169 | [
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0.02731686644256115,
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0.04813717305660248,
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... |
<p>I know in recommender systems you have a rating matrix and then you factorize this matrix into two matrices and then learn those matrices with gradient descent. In those matrices we specify the number of dimensions/latent features that we want. So one of them will be of size $number\_of\_users * k\_latent\_features$... | g61170 | [
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0... |
<p>I have data for 5 replicates that were drawn from the same model and I want to fit all 5 replicates together so that I can find out the shared parameters. Specifically, if I have the underlying distribution - </p>
<p>$$y = Ae^{-mx} + c$$</p>
<p>and then I have 5 output files with x and y (x is the same for all rep... | g61171 | [
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0.... |
<p>I have some sentences. Within that sentences I have some special words:</p>
<pre><code>word1 and word2
</code></pre>
<p>word1 and word2 are exactly same but has different meanings. Given a sentence that contains <code>word1</code> or <code>word2</code> I will try to guess that special word at given sentence has a ... | g61172 | [
-0.007188374176621437,
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0.00018157674639951438,
0.0001257692783838138,
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-0.003505183383822441,... |
<p>I'm using the function <code>compareGrowthCurves</code> in the R package statmod, but I can't seem to find an explanation of what types of curve this is valid for. Does anyone know if there are particular families of functions I shouldn't use this for? </p>
<p>Specifically, I have data on bacterial growth and unde... | g61173 | [
0.040503595024347305,
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0.014... |
<p>I have data that has eta squared values and partial eta squared values calculated as a measure of effect size for group mean differences.</p>
<ul>
<li><p>What is the difference between eta squared and partial eta squared? Can they both be interpreted using the same Cohen's guidelines (1988 I think: 0.01 = small, 0.... | g61174 | [
0.0010713705560192466,
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0.... |
<p>I often run regressions from a low-n dataset (~100 observations). Often the results are only significant with the inclusion of control variables. However, I often see journal articles where people (always with a massive number of observations) claim to have run their regression "with and without control variables".<... | g61175 | [
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0.0... |
<p>Is it possible to plot the estimated log hazard ration in R?
For example,</p>
<pre><code>require(survival)
fit1 = coxph(Surv(futime, fustat) ~ rx, ovarian)
</code></pre>
<p>many thanks in advance.
Tu</p> | g17655 | [
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<p>I have checked with various sources, but I'm still puzzled:
1) What are the exact assumptions of Mood's Median Test?
2) Is homogenity of variance needed for both groups or is the same shape criterion sufficient? </p>
<p>thank you a lot for your help in advance! </p> | g61176 | [
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0.035729821771383286,
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... |
<p>I was reading about unit root test, when I started to get slightly confused about the setting for the Null hypothesis vs Alternative hypothesis, and so I thought of asking the experts opinion.</p>
<p>In the augmented Dickey-Fuller test, the null hypothesis is that there IS a unit root. My confusion comes from the f... | g47378 | [
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<p>I was looking into the <code>DoE.wrapper</code> collection of packages for R and I was interested in generating a split-plot design like I might in JMP. In JMP I can specify all of my factors at the beginning and indicate which of these were "Hard" to change. I then specify how many whole plots that I wanted to ru... | g61177 | [
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... |
<p>Which test should I use, if I want to compare the mean of the whole sample with the mean of the fraction of the sample?</p>
<p>So for example the mean of the whole classroom taking the test and the mean of the girls from that classroom.</p>
<p>Thank you very much!</p> | g61178 | [
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... |
<p>Can someone please give me some intuition as to when to choose either SVM or LR ? I want to understand the intuition behind what is the difference between the optimization criteria of learning the hyperplane of the two, where the respective aims are as follows:
a) SVM: Try to maximize the margin between the closest ... | g17660 | [
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0.0251344982534647,
0.028688199818134308,
0.04191078245639801,
0.06430496... |
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