question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Hopefully, this question will make sense to someone.</p>
<p>I have a multi-valued continuous time series:</p>
<p>$(x, y_1, y_2, y_3, y_4...y_n)$, where $x$ is the time axis.</p>
<p>This time series can be divided into 2 contiguous segments of equal length:</p>
<p>$(x, y_1, y_2, y_3, y_4...y_n)$ for $0 < x <... | g11373 | [
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<p>I'm trying to determine a method to compare one particular time series against about 10,000+ reference time series programmatically, and shortlist those reference time series which can be of interest.</p>
<p>The method I was using was <a href="http://en.wikipedia.org/wiki/Pearson%27s_correlation">Pearson Correlatio... | g49781 | [
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<p>If Stouffer's method of combining k probabilities is based on the variance of the sum being equal to the sum of the variances, and the variance of z is 1, why does the Stouffer formula divide by the square root of k rather than by k?</p> | g37590 | [
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<p>I am doing a simple study that involved taking a measure at time point 1 and time point 2 (12 weeks later). While the sample was a class, not all members were present at both time points, so I have 20 date points at time 1 and 21 date points at time 2. The measure has a score, and I am taking the means and doing a... | g67625 | [
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<p>Let's say I'm working with the following simplified macroeconomic accounting identity</p>
<pre><code> Y_t = C_t + I_t + G_t,
</code></pre>
<p>meaning that GNP in time <code>t</code> equals consumption in <code>t</code>, <code>C_t</code>, plus investment in <code>t</code>,<code>I_t</code>, plus government spending ... | g27236 | [
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<p>I'm implementing a rating system to be used on my website, and I think the Bayesian average is the best way to go about it. Every item will be rated in six different categories by the users. I don't want items with only one high rating to shoot to the top though, which is why I want to implement a Bayesian system.</... | g67626 | [
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<p>From this <a href="https://www.youtube.com/watch?v=Yd6q7Uy6Vpg&list=PLmQpd4sO8qHsPOemZ9cVe_8qirgsREeiH" rel="nofollow">video</a> by Andrew Ng around 5:00</p>
<p><img src="http://i.stack.imgur.com/2TnT1.png" alt="enter image description here"></p>
<p>How are $\delta_3$ and $\delta_2$ derived?
In fact, what doe... | g67627 | [
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<p>$ X \sim N(\mu,\sigma^2) $</p>
<p>$ Y = \frac{\exp(X)}{1+\exp(X)} $</p>
<p>Y has a logit-normal distribution.</p>
<p>When I have a correct estimate of the mean, say $\bar{Y}$, of the logit-normal distribution,
how can use it to get a correct estimate of $\mu$ ?</p>
<p>I don't have full sample from logit-normal d... | g811 | [
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<p>I generated a quantile function $\hat X$ using Monte Carlo simulation.</p>
<p>The random variable I simulate is the mean value of 5 draws from an i.i.d. range statistic $Y$. I.e., I have $Y(\sigma) \sim \sigma F()$, and I simulated the value of $X(\sigma=1) \sim \sum_{1}^{5} y(1)_i / 5$.</p>
<p>Is it valid for me... | g67628 | [
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<p>Disclaimer: I'm a software engineer, not a statistician, so please forgive any blunt error :-)</p>
<p>I have a set of time-series "curves", each measuring the entropy of a given artifact. Now, I'm standing over the following premises (please criticize them as you see fit):</p>
<ol>
<li>In order to approximate the ... | g67629 | [
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<p>When comparing feature-based classification techniques, what characteristics about the different processes should be considered? </p>
<p>I'm comparing different classification techniques to try to figure out what should be considered when selecting a classification technique. In particular, I'm comparing the follo... | g67630 | [
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<p>One way to summarize the comparison of two survival curves is to compute the hazard ratio (HR). There are (at least) two methods to compute this value. </p>
<ul>
<li>Logrank method. As part of the Kaplan-Meier calculations, compute the number of observed events (deaths, usually) in each group ($Oa$, and $Ob$), and ... | g67631 | [
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<p>When testing the difference between 2 proportions why do we use a z-test rather than a t-test? </p>
<p>Further, is there a simple way to conduct an omnibus test for significant differences between more than 2 proportions (in the form of percentages). Is there an equivalent to a one-way ANOVA for this? I imagine t... | g67632 | [
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<p>I am implementing a Random Forest classifier as a side-project, and I am a bit unclear on what the correct approach is to compute, say, the OOB estimate for the classifier error rate. </p>
<p>My understanding is that typically, for each tree in the forest, one creates a training sample from the original sample by ... | g67633 | [
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<p>My spouse frequently works with (expensive, hard to obtain) data samples; for example route information for commuting bicyclists collected using a smartphone app. More often than not, these samples suffer from some kind of known demographic over-representation that they'd like correct for various applications.</p>
... | g47930 | [
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<p>I have a data set with a candidate splitter variable that is a natural choice from the business perspective. It has two values, and the distributions of the target when conditioned on the two values of this variable are quite distinct (visually). Yet the information gain of this variable is very small (almost 80% ... | g67634 | [
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<p>What is the best way to slightly perturb a given discrete probability distribution ? </p>
<p>Adding a zero mean Gaussian noise to the probability distribution and re-normalizing it such that it sums to 1 is one way. But it does not ensure that all the probabilities are positive. Is there an other way to achieve thi... | g27244 | [
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<p>In correlation we can observe relationship between a pair of variables, let me call it X1 and Y. </p>
<p>Now, considering I have the predicting variables X1, X2, ..., Xn and the variable Y. Does the following assumption holds: </p>
<p>If the variables Xi,...,Xj are observed to better classify Y, where 1 <= i,j ... | g67635 | [
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<p>I created a sequence object from my SPELL-formatted data set. The sequence length of the sequence object is 1440 (i.e., 1-min intervals for a day).</p>
<p>Is there any easy way for TraMineR to convert the sequence length from 1440 to 288 (i.e., 5-min intervals), using the status in the first minute of every time in... | g67636 | [
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<p>I have problem in intuitive understanding of full conditional model in building gene regulatory network. it's basically asking that "can correlation between two genes be explained by all other genes in the model?" . and say that, Node i and j are connected if and only if Xi ⊥ Yj | Xrest . my question is that, if Xi ... | g27248 | [
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<blockquote>
<p>A random variable is said to have the Pareto distribution with parameters $\alpha$ and $\beta$, $P(\alpha, \beta)$, if its cumulative distribution function is given by </p>
<p>$$F(x)= 1 - (\frac{\beta}{x})^{\alpha},$$ if $x \geq \beta$, and $0$ otherwise. </p>
<p>a) If $X_1, ... ,X_n$ are ii... | g67637 | [
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<p>I'm learning Bayesian network. I have problem in intuitive understanding of Local Probability Distribution.</p>
<p>Can anybody explain to me what it is? </p> | g67638 | [
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<p>I have data from groups of professionals with in the same medical field. They are grouped according to years in practice. Each group going up in 5 year increments.ie 0-5 yrs experience 6-11 etc. Individually all were asked a set of questions from which I was only interested in one response based on my hypothesis. I'... | g67639 | [
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<p>I want to know if, between two classifications, one provides more homogeneous classes size than the other.</p>
<p>I devised to use the chi square test (classes' size are far more than the rule of thumb of 5 or 10 frequencies), to compare each classification to the most homogeneous classification.</p>
<p>In example... | g35281 | [
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<p>I have a multivariately distributed random 3-vector
$$\mathbf{x}=\begin{pmatrix}x_1\\x_2\\x_3\end{pmatrix}\sim\mathbf{N}\left(\begin{pmatrix}2\\-1\\3\end{pmatrix},\begin{pmatrix}4&1&0\\1&2&1\\0&1&30\end{pmatrix}\right)$$
and I'd like to compute $\text{cov}(x_1x_2,x_1x_3)$. I don't think the f... | g67640 | [
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<p>Is the Kruskal-Wallis test valid when applied to a subset of data? Is there a more appropriate test for comparing the effects of two variables on non-parametric, incomplete data with different variances?</p>
<p>Super simple version
I analyse my data using method A.
A has 6 values.
I have two variables L and P
L has... | g67641 | [
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<p>I have 12 groups of datasets (mostly non-Normal, quite right-skewed), and I would like to see if there is a significant difference within each pair. (But the data itself is not a paired dataset, as in dataset #1 and dataset #2 that I am comparing are from independent populations.)</p>
<p>My data also has outliers (... | g67642 | [
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<p>I have some data I need to analyze, and some prior knowledge I'd like to apply. I have discrete time points, and noisy, continuous outputs $x(t)$ that I observe at those time points, and would like to infer the discrete state $y(t)$ that is most likely to correspond to $x(t)$. If it matters, I know the distributio... | g67643 | [
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<p>I have a dataset containing the performance of a novel instrument to screen for disease A. The novel instrument uses a scoring system to score the subject to determine if they have disease A. I then proceed to use logistic regression to use the novel instrument and demographic variables such as age and gender to cla... | g67644 | [
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<p>I have a set of <code>documents</code> like:</p>
<pre><code>D1 = "The sky is blue."
D2 = "The sun is bright."
D3 = "The sun in the sky is bright."
</code></pre>
<p>and a set of <code>words</code> like:</p>
<pre><code>"sky","land","sea","water","sun","moon"
</code></pre>
<p>I want to create a matrix like this:</p... | g67645 | [
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<p>I want to classify text by different topics. </p>
<p>However, one of the current problems is that there are several topics/categories that are quite intuitively independent and statistically standalone, but there are also several other topics/categories that are quite intertwined with each other.</p>
<p>In order t... | g67646 | [
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<p>I have a number of variables for which I want to compare the standard deviations. Each of these variables is actually the data for a particular wavelength of light, and I want to produce a plot showing the standard deviation for each wavelength.</p>
<p>However, the values that I am calculating my SD from are much h... | g67647 | [
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<p>I'm wondering what difference it makes whether we talk about bias-variance dilemma where fitting a regression line to the given dataset reduces bias and increases variance or whether we talk about overfitting where the model is fitted to the dataset and does not generalize to new datasets.</p>
<p>Essentially overfi... | g67648 | [
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<p>I apologize if question is too simple!</p>
<p>For example, is the probability of generating 2, 8-digit numbers that have the last 4 digits match the same as the probability of the last 4 matching with a 12 digit number?</p>
<p><strong>For an 8 digit number:</strong></p>
<p>10^8 total possible numbers and 10*10*10... | g67649 | [
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<p>Consider $\{X_t\}$ as a general time series including random variables $X_t$. Assume that we have observed $X$'s until time t. The goal is to come up with a function of the observed $X$'s to predict a future X, let's say unobserved $X_{t+h}$. Condsider $h(\vec{X}) = h((..., X_{t-1}, X_t))$ as our proposed function. ... | g27252 | [
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<p>In penalized/regularized regression (lasso, ridge, etc.) the predictors are typically standardized to be centered at 0 and often to have variance 1. Are categorical predictors treated differently. If so, why? What are the consequences of using the same standardization? Is a reference available?</p> | g27253 | [
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<p>I am performing a regression in which I suspect there could be endogeneity between the main explanatory variable and the dependent. As a first step I perform an OLS regression and then, to control for the endogeneity, I use a 2SLS regression with an instrumental variable.</p>
<p>The coefficient for this variable in... | g67650 | [
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<p>I'm helping someone with prep for their stats assessment and they are being instructed to use the following to make an informal inference about the population:</p>
<p><img src="http://i.stack.imgur.com/ok0Fd.png" alt="Figure"></p>
<p>I was wondering if there is any statistical basis to these figures or how it was ... | g67651 | [
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<p><img src="http://i.stack.imgur.com/DOMHz.jpg" alt="enter image description here"></p>
<p>Using Kolmogorov's forward and backward equations, show that $p_{11}(t) + p_{21}(t) + p_{31}(t) = 1$ and $p_{21}(t) = p_{31}(t)$ where $p_{ij}(t) = P(X(t) = j | X(0) = i)$.</p>
<p><strong>My attempt:</strong></p>
<p>I can sho... | g67652 | [
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... |
<p>I'm not a statistics guy but want to investigate a problem like this:</p>
<p>I have a number (hundreds) of trends that I wish to use to come up with an average trend. My method was to be by using the average value of the individual trend at each time step, to come up with the average, then fit this new average tren... | g67653 | [
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<p>Using Laplacian Smoothing we can get rid of 0 probabilities if a term occur in spam and does not occur in ham class or vice versa. My question is about what if a term in test document does not occur in training dataset(i.e. in dictionary). For example if we extend example in page 44 in -> <a href="http://www.stanfo... | g12776 | [
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<p>I have a set of data created by users answering a questionnaire. I imported their answers from a .csv file and got them as a data frame with one user per row and one question per column. </p>
<p>However, the questions were not homogenous. I have to first evaluate some questions, which gives me an ordered list of th... | g27256 | [
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<p>Neural Networks are usually trained using a gradient based learning algorithm, such as the back propagation algorithm or some variant of it, but can you use global optimization algorithms, such as the Genetic Algorithm, Nelder-Mead Polytope Algorithm, and Particle Swarm Optimisation to train the network?</p>
<p>Sin... | g67654 | [
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<p>In order to find the minimax solution of a certain problem I have to determine the constant $c$ that provides the root for the following equation:</p>
<p>$$l(c)=3\times \left [ 1-\Phi \left( c-75 \right) \right]-\Phi \left(c-78 \right)=0$$</p>
<p>where $\Phi (.) $ is as usual the CDF of a standard normal random va... | g67655 | [
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<p>The solution to the problem:</p>
<p>$$ \min_{m} \; E[|m-X|] $$ </p>
<p>is well known to be the median of $X$, but what does the loss function look like for other percentiles? Ex: the 25th percentile of X is the solution to:</p>
<p>$$ \min_{m} \; E[ L(m,X) ] $$</p>
<p>What is $L$ in this case? </p> | g27258 | [
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<p>Due to limitations in experimental setup, I only have small data sets with n=3. Despite the low df the difference between treated and control is large enough to generate a significant p-value.</p>
<p>The problem is that with small sample sizes doing a t-test becomes more sensitive to the assumption that the data ar... | g67656 | [
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<p>I would like to understand a couple of fact on maximum likelihood estimators (MLEs) for logistic regressions.</p>
<ol>
<li><p>Is it true that, in general, the MLE for logistic regression is biased? I would say "yes". I know, for example, that sample dimension is related to the asymptotic bias of MLEs. </p>
<p>Do y... | g27260 | [
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<p>I was attempting to find the IQR for a normal distribution with mean being 4.5, while the standard deviation. </p>
<p>My attempt yielded the result <strong>2.144</strong>, while the actual answer provided was <strong>2.1584</strong>.</p>
<p>Following is my workings, appreicate if anyone will be able to guide me wh... | g67657 | [
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<p>By regularization techniques I'm referring to lasso, ridge regression, elastic net and the like.</p>
<p>Consider a predictive model on health care data containing demographic and diagnosis data where length of stay for inpatient stays is being predicted. For some individuals there are multiple LOS observations (i.e... | g35753 | [
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<p>Instrumental variables (2SLS) regression<br>
Number of obs = 603</p>
<p>F( 5, 597) = 41.96</p>
<p>Prob > F = 0.0000</p>
<p>R-squared = 0.1386</p>
<p>Root MSE = .26523</p>
<pre><code> |
logwage | Coef. Std. Err. t P>|t| [95% Conf. Interval]
... | g27264 | [
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-0.015528066083788872,
0.03536820039153099,
0.029818594455718994,
0.07575000077486038,
-0.0082... |
<p>I am running a regression to estimate the relationship between a dependent variable and some regressors. Let's say I have two alternative models based on two different assumptions about the exogeneity of the regressors involved. Therefore I get two set of parameters, say <code>ß</code> and <code>b</code>, both of th... | g27265 | [
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0.0032294250559061766,
0.01685602404177189,... |
<p>I'm trying to identify structural breaks in the movement of reserve currencies. I'm not yet all that versed in the finer details of time series, but I've been reading up on ARCH and GARCH estimators. However, in my model I don't really want to look at any external factors, like government interventions, gdp, macroec... | g27266 | [
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0.06878822296857834,
-0.033... |
<p>After lemmatization of text I have a sequence of sets of lemmas, because every word can correspond to more than one lemma. How should I extract ngram statistics based on that? The only thing that comes to mind is counting every possible combination, but this seems a bit weird. Is there any other option?</p>
<p>More... | g622 | [
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<p>Suppose I aim to examine if treatment A is better than treatment B.
My dataset consists of 10,000 individuals with a total of 100,000 observations. Thus each individual is observed 10 times and his covariates (blood pressure, blood lipids etc) are updated each visit. To provide more robust estimates, I use all obser... | g67658 | [
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0.037... |
<p>My goal is to fit a cox regression model in SAS, for which I use the <code>PROC PHREG</code> statement. As I am still new to regression methods, I would appreciate a little of your help. My procedure is as follows:</p>
<p>First, I check all variables in a univariate regression and select those, which have a p-value... | g67659 | [
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<p>I have a dataset which I need to spot trends in. The actual data refers to operation calls which take a certain amount of time to complete. My client wants to know which operation calls are improving and which are deteriorating over a time period.</p>
<p>Each operation call has an entry for each day which shows th... | g27267 | [
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<p>Let say I have a 'kidney catheter' data set which is built in <code>survival</code> package. Data are about the recurrence times to infection, at the point of insertion of the catheter, for kidney patients using portable dialysis equipment. Catheters may be removed for reasons other than infection, in which case the... | g67660 | [
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0.0550... |
<p>I have wind data that i'm using to perform extreme value analysis (calculate return levels). I'm using <em>R</em> with packages 'evd', 'extRemes' and 'ismev'.</p>
<p>I'm fitting GEV, Gumbel and Weibull distributions, in order to estime the return levels (RL) for some period T.
For the GEV and Gumbel cases, i can ge... | g67661 | [
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<p>I have checked the existing answers, but I found no answer to my question. It is about choosing the right ANOVA model in R and how the MSresiduals are estimated. </p>
<p>I have an experiment with two factors: <code>MANAGEMENT</code> and <code>REGION</code>. I have three <code>MANAGEMENT</code> types and three <code... | g27268 | [
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<p>suppose to have sample from 3 groups A,B,C.
The hypothesis <code>H0: the mean of the 3 groups is the same</code> can be tested using 3 independent t test. </p>
<pre><code>test1: mean(A)=mean(B) level 0.05
test2: mean(B)=mean(C) level 0.05
test3: mean(A)=mean(C) level 0.05
</code></pre>
<p>It's known that we should... | g309 | [
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<p>I believe that this question is sufficiently different from previous related ones to warrant a new post. (I apologize if it has been answered already)</p>
<p>I need to decide between various resampling methods to "best" (highest power and correct type-I error to reject H0 for the right reasons) evaluate auto correl... | g67662 | [
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-0.00897930283099413,
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-0.03595319017767906,
0.00017525690782349557,
0.02540610358119011,
0.021980812773108482,
0... |
<p>I am using the "FNN" package to calculate the Kullback-Liebler Divergence between two numeric vectors:</p>
<pre><code>require(FNN)
load("~/xy.RData")
KL.divergence(x,y)
</code></pre>
<p>(Link to the data file is given at the bottom)</p>
<p>The result is:</p>
<pre><code>NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN
</c... | g67663 | [
0.03187362104654312,
-0.017966529354453087,
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-0.08640351891517639,
0.043331947177648544,
-0.018998900428414345,
0.025216810405254364,
-0.026417527347803116,
-0.02578994818031788,
-0.03873134031891823,
-0.04269040748476982,
-0.01854398287832737,
-0.004571960307657719,
... |
<p>Suppose a model,</p>
<p>$$x_{i} \sim N(\theta_{i}, \phi), \text{ for } i=1,\ldots,n$$</p>
<p>Furthermore, suppose the variance parameter, $\phi$, is some known constant.</p>
<p>The multidimensional Jeffreys prior is defined as,</p>
<p>$$\pi(\vec{\theta}) \propto \sqrt{\text{det}I(\vec{\theta})}$$</p>
<p>where $... | g67664 | [
0.020050566643476486,
-0.024231135845184326,
-0.01055039931088686,
-0.04969526082277298,
0.00012783911370206624,
-0.007181775290518999,
-0.010179550386965275,
-0.004185476340353489,
-0.029722975566983223,
0.013728712685406208,
-0.013804418966174126,
0.027836274355649948,
-0.02301838621497154... |
<p>I have the following process:</p>
<p>I have N buckets in front of me, $M$ of which are filled with water (the other ones are empty). </p>
<ol>
<li>I pick one of them (consider uniform distribution) and empty it (so now I have $M-1$ of them filled with water). </li>
<li>Afterwards $P$ more get filled with water (p... | g37877 | [
-0.005113911349326372,
0.016528720036149025,
-0.04495818540453911,
-0.05522844195365906,
0.007467101328074932,
-0.022738007828593254,
0.05215755105018616,
-0.006533365696668625,
-0.033654481172561646,
0.021104346960783005,
-0.019711680710315704,
-0.031145833432674408,
0.05468405410647392,
... |
<p>Here is the <a href="http://en.wikipedia.org/wiki/Three_Prisoners_problem#Mathematical_formulation" rel="nofollow">wiki</a> of Three-prisoner problem, in which only one prisoner is pardoned, and the Bayes solution is given in the wiki.</p>
<p>My problem is pretty much the same, except that only one prisoner is exec... | g67665 | [
0.05421370640397072,
0.01693340763449669,
0.012650949880480766,
-0.025492098182439804,
0.033816225826740265,
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0.010730244219303131,
0.04757620766758919,
-0.05411423370242119,
0.019063521176576614,
0.012952806428074837,
0.08977020531892776,
-0.008434455841779709,
-0.00... |
<p>I have two multi variate normal distributions N1 and N2.
Say two points p1 is from N1 and p2 is from N2.
I want to get some statistical features from these two points. How can I do it?</p>
<p>I need a richer representation (not one number). Say my points are in a d dimensional space, in that case I need a d dimensi... | g47952 | [
0.020609447732567787,
-0.04161684587597847,
-0.026783771812915802,
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-0.012982391752302647,
-0.015484176576137543,
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0.031024137511849403,
-0.040673647075891495,
-0.025999674573540688,
0.010671987198293209,
0.035260215401649475,
0.04651465639472008,
... |
<p>My dataset consists of 4,000 companies from 24 countries. Each company has certain features, the IV's. Consider the variable list below: green is the DV, red the IV's and blue are dummies (one for each country a company might be from) for which I want to control the OLS output. There are 24 countries entered.</p>
<... | g41631 | [
-0.017696795985102654,
0.0009396925452165306,
-0.053293000906705856,
-0.07073154300451279,
0.034148652106523514,
-0.0006176870665512979,
-0.007526142057031393,
0.023322297260165215,
-0.016976933926343918,
-0.026509558781981468,
-0.03129241243004799,
0.03861772269010544,
0.05174073949456215,
... |
<p>I have a β-distribution(which looks like a normal distribution), for which I want to calculate the values of α and β using maximum likelihood estimation method. I am new to statistics, so would like to know if there is any tool available which can be used to compute these parameters.</p>
<p>PS: Similar question has... | g35756 | [
0.03271118551492691,
-0.0720847025513649,
0.0179259292781353,
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0.051062121987342834,
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0.00180725974496454,
-0.022006705403327942,
-0.005271262489259243,
0.055803943425416946,
0.05357... |
<p>SAS code : </p>
<pre><code>data pr;
input y x1 x2 @@;
cards;
5 2 2 7 3 3 3 2 0
5 2 4 4 3 3 7 2 4
;
run;
proc reg data = pr;
model y = x1 x2; run; quit;
</code></pre>
<p>When I run the regression procedure,
I got the result </p>
<pre><code>[F-test : p-value for model = 0.3757]
[t-... | g67666 | [
0.03509226068854332,
0.04070931673049927,
-0.010545470751821995,
-0.012221946381032467,
0.04273509606719017,
-0.011058601550757885,
0.04150659590959549,
0.01070481538772583,
-0.07772941887378693,
-0.0733204036951065,
0.011257767677307129,
0.01781810075044632,
0.04961580038070679,
0.0156160... |
<p>I am trying to estimate a production function called Cobb-Douglas.</p>
<p>For the period 1958 to 1972 and for the agricultural sector in Taiwan, we observed:</p>
<pre><code>An: Year of observation
Y: Real production in millions New Dollars Taiwan (NDT)
L: Day of Labour, in millions
K: Real Capital in millions de N... | g67667 | [
0.00009268085705116391,
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-0.034081608057022095,
-0.00564557034522295,
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0.06831140071153641,
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-0.007400407921522856,
-0.010087564587593079,
-0.030024202540516853,
0.008462517522275448,
0.025242000818252563... |
<p>Currently I am working on my master thesis which is about risk-adjusted returns (Sharpe ratio) of Asian REITs. I just transformed all the data in variables which are ready to use in Stata.</p>
<p>My data consist of year (2002 till 2012), Key (cusip identifier), Country, and all sorts of firm specific characteristic... | g67668 | [
0.026798641309142113,
0.005377463065087795,
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0.027531517669558525,
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0.03031279146671295,
0.014523682184517384,
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0.008379174396395683,
-0.012645775452256203,
0.039672546088695526,
-0.007962284609675407,
... |
<p>Sorry about asking such a basic question. </p>
<p>Assuming I have data like this </p>
<p><code>x Trial1 Trial2 Trial3
1 1.0 2.0 3.0
2 1.1 2.1 3.1
3 1.2 2.2 3.2
</code></p>
<p>How exaclty to I regress my predictor variable x onto my data. I was thinking naively that I could just take... | g67669 | [
0.011072670109570026,
-0.047682370990514755,
-0.03202636539936066,
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0.0435795933008194,
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0.027371492236852646,
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-0.03584141656756401,
0.0025048155803233385,
0.05203273892402649,
0.03352015092968941,
0.020... |
<p>We are investigating the effects of a treatment (versus untreated control) on insect abundance. The study consists of 5 geographically separated study site replicates. Treatments were applied to 1 ~500 acre area at each location. Insects were collected from 14 randomly selected locations within the treatment area ... | g27276 | [
-0.026412833482027054,
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-0.02841823361814022,
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0.011097023263573647,
0.006757818628102541,
0.06009409576654434,
0.004139236640185118,
-0.0003251809102948755,
0.051604367792606354,
-0.049223728477954865,
0.0019929322879761457,
... |
<p>Suppose I have a sample from a multinomial distribution $\text{Multi}(p_1,\ldots,p_k)$, where $p_1+\dots+p_k=1$. I'd like simultaneous confidence intervals for the $p_i$'s. That is, for any $\alpha\in(0,1)$, I want to define $\ell_i$'s and $u_i$'s (random variables depending on the random sample) such that
$$
P(p_... | g47957 | [
0.010716690681874752,
0.02248823456466198,
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0.01621483825147152,
0.006630712654441595,
0.002105673076584935,
0.029651015996932983,
0.... |
<p>If I understand correctly, PCA's principle is very simple:</p>
<ol>
<li>Calculate data vectors' covariance matrix <strong>C</strong>.</li>
<li>Solve det(<strong>C</strong> - <strong>e</strong>*I) = 0, to find matrix <strong>C</strong>'s eigenvalues <strong>e</strong>.</li>
<li>Calculate matrix <strong>C</strong>'s ... | g67670 | [
0.03283276408910751,
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0.012122116051614285,
-0.06408350169658661,
0.025445373728871346,
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0.04427776858210564,
0.03160518407821655,
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0.00028674289933405817,
-0.04558016359806061,
-0.025521770119667053,
0.05183147266507149,
0.013... |
<p>Suppose we want to make inference on an unobserved realization $x$ of a random variable $\tilde x$, which is normally distributed with mean $\mu_x$ and variance $\sigma^2_x$. Suppose there is another random variable $\tilde y$ (whose unobserved realization we'll similarly call $y$) that is normally distributed with ... | g27277 | [
-0.00738427834585309,
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-0.030632972717285156,
-0.06411600112915039,
0.001467449008487165,
0.0353817380964756,
0.015103128738701344,
0.011942096054553986,
-0.02370547689497471,
-0.003875709604471922,
-0.029184699058532715,
0.04996364936232567,
-0.0002113646623911336,
0... |
<p>Let's say that there exists some "true" relationship between $y$ and $x$ such that $y = ax + b + \epsilon$, where $a$ and $b$ are constants and $\epsilon$ is i.i.d normal noise. When I randomly generate data from that R code: <code>x <- 1:100; y <- ax + b + rnorm(length(x))</code> and then fit a model like <co... | g27279 | [
0.033488303422927856,
-0.04554640129208565,
-0.051775190979242325,
0.0134249497205019,
0.06922652572393417,
-0.005968470126390457,
0.032749682664871216,
-0.007041424512863159,
-0.03583873063325882,
0.0001898779155453667,
-0.025171855464577675,
0.05810512974858284,
0.027922600507736206,
0.0... |
<p>From <a href="http://stats.stackexchange.com/q/62680/1005">discussion with Nick Cox</a>, and some search, I was wondering what are the definitions of model-based classification and non-model-based classification?</p>
<p>My understanding is that for model based classification, there is a statistical model for the jo... | g67671 | [
0.052521999925374985,
-0.043631959706544876,
0.006793075241148472,
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0.03877755254507065,
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0.03059094399213791,
0.013265931978821754,
0.0005732872523367405,
-0.05178450047969818,
0.008737574331462383,
0.007377676200121641,
0.13329856097698212,
0.000... |
<p><em>Is there any way to compute 95% confidence intervals and prediction interval for the predicted value at each node?</em></p>
<p>Thanks!!!</p> | g12877 | [
0.006636515725404024,
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0.012797444127500057,
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0.005898242350667715,
0.06250213086605072,
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-0.03341086953878403,
0.004238767083734274,
0.02026999555528164,
0.04926005378365517,
-0.030... |
<p>I need to show that the proportion of different cell types in blood from two individuals are the same. </p>
<p>Example: There are 6 cell types and </p>
<pre><code> Person 1 has the proportions: 0.07, 0.05, 0.4, 0.3, 0.15, 0.03 (Sums to 1)
Person 2 has the proportions: 0.07, 0.05, 0.3, 0.2, 0.35, 0.03 (Sums ... | g27283 | [
0.05760809779167175,
-0.008367666974663734,
0.015462656505405903,
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0.03721383213996887,
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0.030372777953743935,
0.043783798813819885,
0.014866639859974384,
0.013223671354353428,
... |
<p>There are two variables, $x$ and $y$, with $y$ depending on $x$ somewhat. For each occurrence of $x$, I record the value of $y$ so that I get a frequency distribution for $y$ given $x$. (The parentheses are to be read as (value, frequency) for $y$.) </p>
<pre><code>x = 0: (19,2) (20,2) (35,5) (36,7)
x = 1: (14... | g67672 | [
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0.012469221837818623,
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0.047496695071458817,
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-0.005119600798934698,
-0.021289866417646408,
0.021886633709073067,
0.031369902193546295,
0.0... |
<p>I am working with linear regression methods. The weakness of the method is the possibility of overfitting. So to reduce it, some papers use regularization. Are there other methods to reduce overfitting? Can we use a prior term to reduce overfitting? </p>
<p>Given $D=\{(x_1,y_1);(x_2,y_2)...(x_n,y_n)\}$, the linear ... | g67673 | [
0.04229224473237991,
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0.016532039269804955,
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-0.017461642622947693,
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0.01719958707690239,
-0.012240434996783733,
... |
<p>I am a newbie with pyMC and I am not still able to construct the structure of my MCMC with pyMC. I would like to establish a chain and I am confused how to define my parameters and log-likelihood function together. My chi-squared function is given by:</p>
<p><img src="http://i.stack.imgur.com/9o5rz.gif" alt="enter ... | g67674 | [
0.017816228792071342,
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0.05297698825597763,
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0.03345469385385513,
0... |
<p>Given two time series, the problem is to find out correlated regions (by finding out the starting and ending points of those regions). </p>
<p>For example, in the image: <img src="http://i.stack.imgur.com/c975u.png" alt="enter image description here">, the upper time series is a stock trend, the lower time series i... | g67675 | [
0.044406402856111526,
0.030351215973496437,
0.00318250828422606,
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0.005153097677975893,
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0.0324941985309124,
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0.0... |
<p>When building decision trees over a dataset that generates nodes with bad purity, is there any benefit of using the CART algorithm over the <a href="http://en.wikipedia.org/wiki/ID3_algorithm" rel="nofollow">iterative dichotomizer 3</a> (ID3) algorithm?</p> | g27284 | [
-0.008498741313815117,
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0.04109842702746391,
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0.08318394422531128,
0... |
<p>I have a data set that includes two sub-tests, each measured using a Likert scale.
I want to test the reliability.</p>
<p>Is it necessary to calculate Cronbach’s Alpha for each sub-test? Or do I have to calculate just one Cronbach’s Alpha for all data?</p> | g47967 | [
0.04209531843662262,
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<p>It's been a while since I've taken stat class so I would like help solving this problem.</p>
<p>If the probability of a event occurring, like a person falling when they take a step, is 0.001%, then what is the probability of that person falling at least twice in a row in 1000 steps? </p>
<p>Then what is the proba... | g92 | [
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... |
<p>I'm trying to wrap my head around using a linear mixed model and appropriate post-hoc tests to determine if there is a significant difference between various treatments in an experiment I inherited. (I'm really not sure if this question is more stats or more R, as it definitely contains elements of both.)</p>
<p>T... | g67676 | [
0.026455681771039963,
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0.0032350595574826,
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0.03... |
<p>What is the difference between training, test, and holdout sets?</p>
<p>I know these concepts, just want to ensure that I have understood correctly.</p>
<p>Training set is something that we have as of now. We will remove subset from it and removed subset will be called holdout set. </p>
<p>We will build models us... | g27285 | [
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0.03383934870362282,
0.018972329795360565,
-0... |
<p>I have a dataset with mostly financial variables (120 features, 4k examples) which are mostly highly correlated and very noisy (technical indicators, for example) so I would like to select about max 20-30 for later use with model training (binary classification - increase / decrease).</p>
<p>I was thinking about us... | g67677 | [
0.004868056159466505,
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0.02901332825422287,
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0.02231086790561676,
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0.01714712381362915,
0.0020138989202678204,
0.03847748041152954,
0.028528301045298576,
0.03943... |
<p>I have 4 sets of 50 year data (one value per year for each of the 4 different categories)- and would like to test for differences in the slopes of the lines. I think ANCOVA is appropriate- though maybe not as these are time series data? And ...how to do post hoc pairwise comparisons?</p>
<p>The data are estimate... | g37520 | [
0.016993343830108643,
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-0.001992330886423588,
-0.048994340002536774,
-0.01166911143809557,
0.06493012607097626,
-0.06005832552909851,
-0.05420438572764397,
0.044272031635046005,
0.006777729839086533,
0.02064959518611431,
0.007090450264513493,
0.0... |
<p>For my time-series regression, I am regressing the difference in variable x on a difference in variable y. Before proceeding, I want to check for stationarity of my variables. Regressing d.x (difference in x) over L.d.x (lag of the difference in x), I get a coefficient of $-0.9995261$ and a 95% interval: $[-1.000654... | g67678 | [
0.010035660117864609,
-0.028393326327204704,
-0.0025348844937980175,
-0.025131048634648323,
0.018376264721155167,
-0.01747359335422516,
0.08181320875883102,
0.016114382073283195,
-0.02899414859712124,
-0.034489765763282776,
-0.008800482377409935,
0.058198653161525726,
0.05919612571597099,
... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/534/under-what-conditions-does-correlation-imply-causation">Under what conditions does correlation imply causation?</a><br>
<a href="http://stats.stackexchange.com/questions/30156/can-somebody-illustrate-how... | g49340 | [
0.062483374029397964,
-0.0025898630265146494,
0.004972140304744244,
-0.011323017068207264,
-0.009480539709329605,
0.017599651589989662,
0.03857653588056564,
0.005951350089162588,
0.014409502036869526,
-0.028471065685153008,
0.0004164408892393112,
0.022401101887226105,
0.037222981452941895,
... |
<p>I have a need to build a classifier for time series data. I've made progress but would like advise on my current challenge (see below).</p>
<p>My research led me to KNN and Dynamic Time Warping as the distance measure. This has performed very well on a small dataset. Unfortunately, it is computationally intensive.<... | g67679 | [
-0.02242014743387699,
-0.0024327326100319624,
-0.007892393507063389,
-0.051123421639204025,
-0.048691947013139725,
-0.06318672746419907,
-0.020172948017716408,
0.032961126416921616,
-0.03422224149107933,
-0.010478594340384007,
0.04257119074463844,
0.025601305067539215,
0.07307671010494232,
... |
<p>I get enormous coefficients during logistic regression, see coefficients with <code>krajULKV</code>:</p>
<pre><code>> summary(m5)
Call:
glm(formula = cbind(ml, ad) ~ rok + obdobi + kraj + resid_usili2 +
rok:obdobi + rok:kraj + obdobi:kraj + kraj:resid_usili2 +
rok:obdobi:kraj, family = "quasibinomial"... | g67680 | [
-0.025340896099805832,
-0.06533482670783997,
0.0074602882377803326,
-0.006204995792359114,
0.06824466586112976,
-0.03196314722299576,
0.09258725494146347,
-0.012083069421350956,
-0.025031577795743942,
0.01915648579597473,
-0.06145111098885536,
0.08076689392328262,
0.08768817782402039,
0.00... |
<p>This is a simple question, not really related to coding but more so to some math that I am missing in my brain.</p>
<p>I know: </p>
<p>An object A has a length of 5 and a mean of 4.
An object B has a length of 10 and a mean of 7.
I make a new object, C, where C <- c(A, 1, B).</p>
<p>What is the mean of C?</p> | g67681 | [
0.022275349125266075,
0.043978702276945114,
-0.0025134170427918434,
-0.10434984415769577,
0.0680212676525116,
-0.01905370131134987,
0.0031620466616004705,
-0.021261446177959442,
-0.06879651546478271,
-0.04762061685323715,
-0.10602328181266785,
-0.0019729691557586193,
0.04534197971224785,
0... |
<p>Can anyone expalin to me in simple terms what happens when we use weights in <code>regsubsets</code> or <code>lm</code> in R? What effect do weights have on a linear regression?
for example : </p>
<pre><code>Model1<-lm(Ozone~Solar.R,data=airquality)
summary(Model1)
#Coefficients:
# Estimate Std. Erro... | g67682 | [
0.01976296864449978,
-0.05087099224328995,
-0.025090770795941353,
-0.026284942403435707,
0.025361377745866776,
0.013068418949842453,
0.09086086601018906,
0.02165057882666588,
-0.07033859938383102,
-0.044109318405389786,
-0.04426486790180206,
0.0414079912006855,
0.0469791442155838,
0.021672... |
<p>Consider the generalized hyperbolic distribution given by (from wikipedia):
<img src="http://i.stack.imgur.com/GYWx0.png" alt="gh"></p>
<p>So I now wanted to derive the standardized version, so mean zero variance one. I wanted to do the following:</p>
<ol>
<li>Set the mean to zero and the variance equal to one.</l... | g67683 | [
-0.008715314790606499,
-0.02338993363082409,
-0.01088800560683012,
-0.00255948887206614,
0.11482849717140198,
-0.004342634696513414,
0.006639416795223951,
0.061979129910469055,
-0.0615808479487896,
-0.029344188049435616,
-0.03281978890299797,
0.010419790633022785,
-0.017845958471298218,
0.... |
<p>I am working on the data set <code>electricity</code> available in R package <code>tsa</code>. My aim is to find out if an <code>arima</code> model will be appropriate for this data and eventually fit it. So I proceeded as follows: <br/> <br/>1st: Plot the time series which resulted if the following graph: <img src=... | g67684 | [
0.042737796902656555,
-0.012672039680182934,
-0.030513061210513115,
-0.04646050184965134,
0.015446316450834274,
0.017361633479595184,
0.05157957598567009,
0.01334492675960064,
-0.06625430285930634,
-0.029467174783349037,
0.048214200884103775,
0.041464317589998245,
0.027462324127554893,
-0.... |
<p>I am interested in the standardized version (mean zero, variance one) of the generalized hyperbolic and the hyperbolic distribution. I want to include this in my analysis and therefore I need the dervations and the implementations. In R, there is an <a href="http://help.rmetrics.org/fBasics/dist-sgh.html" rel="nofol... | g49468 | [
0.030771972611546516,
-0.01020273007452488,
-0.025110874325037003,
-0.04476098716259003,
0.0010148038854822516,
-0.044591598212718964,
0.014546817168593407,
0.08086944371461868,
-0.049624405801296234,
-0.05976451188325882,
-0.05119040235877037,
0.002746222773566842,
0.03703984245657921,
0.... |
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