question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have read that inferences on heterogeneity should be applied with caution if there are few studies. I have 6 studies for meta analysis.</p>
<ul>
<li>Is 6 studies sufficient to assess heterogeneity of effect sizes?</li>
<li>How many studies are required to assess heterogeneity?</li>
<li>What is the consequence of ... | g63711 | [
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<p>In the beginning of an experiment, subjects are required to report on their initial emotions / mood using Questionnaire#1. After the experiment is conducted, the subjects fill another mood questionnaire#2. </p>
<p>How do we interpret these two sets of data (from the initial questionnaire and the final questionnaire... | g63712 | [
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<p>I am currently facing a big issue with regard to my master thesis. I developed following hypotheses:</p>
<p>Hypothesis 1: Managers’ investment in innovation increases when the organization is judged in decline state <em>(<strong>positive</strong> relationship between organizational decline and investments in innova... | g63713 | [
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<p>I have a sample with 181 observations. I measured two nominal variables for each observation and now want to calculate the association between the two variables. The problem is that one variable has 15 possible values, the other one 16. So when I tried to compute Cramér's V, R complained that "Chi-squared approximat... | g10428 | [
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<p>Let me start by saying that I'm really not an expert in statistics/econometrics.</p>
<p>Now to my questions: I have a data set containing weekly prices of a stock. I want to check whether a structural break has occurred at a specific date using a Chow test. I know how to conduct it (using EViews 7), but I'm not sur... | g63714 | [
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<p>Is there a way to find an optimal threshold? I am using MATLAB for this project.</p>
<p>I have 2 groups of triangles (distances and angles). I need to find the similarities between two triangles in each set. I order the distances from largest to smallest. I need to compare distances and angles. If they are below a... | g63715 | [
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<p>An insurance company is reviewing its current policy rates. When originally setting the rates they
believed that the average claim amount was $1,800$. They are concerned that the true mean is actually
higher than this, because they could potentially lose a lot of money. They randomly select 40 claims, and
calculate ... | g63716 | [
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<p>Reading materials from differents sites some questions have risen about covariance and the pooled covariance matrix calculation to implement LDA:<br>
<strong>Definitions</strong><br>
Ci - covariance matrix of group i (C1 and C2)<br>
C - pooled covariance matrix<br>
u - global mean (dataset)<br>
ui - mean fo group... | g13441 | [
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<p>As part of my MSc, I have recently developed a web application designed to assist toddlers with learning difficulties in the comprehension of spoken instruction. The system shows a series of animations to convey an object and then tasks the child to pick out the correct object from a series of objects. I then coll... | g4359 | [
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<p>I'm a CS master student focusing on data mining. Now I'm doing my master thesis and the contribution of my thesis is to compare different approaches/methods of one topic (e.g. clustering of text documents). What I did so far is looking at the state of the art on the topic and read the papers. However now I need to t... | g14237 | [
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<p>Can nominal data have uncountably many values?</p>
<p>Are categorical data the same as nominal data?</p>
<p>Are discrete data the same as nominal data?</p>
<p>Thanks!</p> | g63717 | [
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<p>I would like to ask the opinion of this community in regard to the following discussion between me and my colleague. The case is this: we have two variables, let's call them Y and X. The AIC of a simple linear regression of Y on X <code>(Y = b1*X + e)</code> is A, and the AIC of the reversed model, regression of X o... | g63718 | [
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<p>I have made <a href="https://github.com/statsmodels/statsmodels/pull/1287" rel="nofollow">python code</a> for exponential smoothing (ES) that takes in about 15 different cases including:</p>
<ul>
<li>Simple Exponential Smoothing (SES)</li>
<li>Simple Seasonal models (both multiplicative and additive)</li>
<li>Brown... | g63719 | [
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<p>My aim is to generate multidimensional binary data with specified correlation between the dimensions. Let's assume that there are 100 items grouped under 2 dimension that are correlated at specified level</p> | g63720 | [
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<p>I'm very new to the statistic methods but at the beginning of my wonderful math-journey I found some problems. </p>
<p>Two days ago I got to know the ANOVA method. I'm kind of familiar with it today, but there's one issue that I can not understand. </p>
<p>I know how to calculate F, and df1 so as df2. But how abou... | g63721 | [
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<p>I am concerned with the problem that I would like to bootstrap the p-value for an estimate of $\theta$ from multiply imputed (MI) data, but that it is unclear to me how to combine the p-values across MI sets.</p>
<p>For MI data sets, the standard approach to get to the total variance of estimates uses Rubin's rules... | g21528 | [
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<p>I am completing a factor analysis with 105 items and am having some problems. When I look at the scree plot for the "elbow" it suggests that there a 5 factors, however these five factors only account for 43% of all the variance. Looking at the eigen values it suggests that there are 23 factors….</p>
<p>The items ... | g63722 | [
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<p>I was wondering at what lags should I perform the Ljung Box test on on standardised squared residuals. I used fGarch and the tests were done at lag 5,10 and 15 respectively with no evidence to reject the null hypothesis. However, I tried using rugarch as it has functions that fGarch doesn't have but the ljung box te... | g63723 | [
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<p>I want to analyse the following data: 12 populations have been followed and a certain illness in the population is measured. I am interested in the probability of being ill.</p>
<p>Now I divide these populations in males and females which would have their own probabilities in turn (I could in theory slice and dice ... | g13466 | [
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<p>I know there is k-means clustering algorithm and k-median. One that uses the mean as the center of the cluster and the other uses the median. My question is: when/where to use which?</p> | g21531 | [
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<p>I had read wiki and some sources.
<a href="http://jmanton.wordpress.com/2010/06/05/comments-on-james-stein-estimation-theory/" rel="nofollow">jmanton's blog</a>,
<a href="http://normaldeviate.wordpress.com/2013/05/18/steins-paradox/" rel="nofollow">Wasserman's blog</a></p>
<hr>
<p>the background is that:</p>
<p>... | g63724 | [
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<p>In this particular case I'm referring to the day on which a lake freezes. This "ice-on" date only occurs once a year, but sometimes it doesn't occur at all (if the winter is warm). So on one year the lake may freeze on day 20 (january 20th), and another year it might not freeze at all.</p>
<p>The goal is to figure ... | g10431 | [
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<blockquote>
<p>Let $\theta(F)=2\int^1_0(t-q_F(t))dt$, where $\displaystyle q_F(t)=\frac{\int_0^tF^{-1}(s)ds}{\int_0^1F^{-1}(s)ds}$.</p>
</blockquote>
<p>For discrete distributions I'm assuming that $F^{-1}(s)=\inf\{x:F(x)=s\}$ (the quantile function).</p>
<p>The exercise next defines a discrete distribution functi... | g63725 | [
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<p>I'm reading through Fan and Li's <a href="http://orfe.princeton.edu/~jqfan/papers/01/penlike.pdf" rel="nofollow">SCAD</a> paper on Nonconcave Penalized
Likelihood. The idea is to penalize the loss function by $p_\lambda(\theta)$ where $\lambda$ can be some tuning parameter. Fan proposes that a proper penalty functio... | g63726 | [
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<p>I'm looking to use the ACSI (American Customer Satisfaction Index) for a customer satisfaction survey. I'm confused by the explanation for how to calculate this. The survey is three questions:</p>
<ol>
<li>What is your overall satisfaction with [our product or service]?</li>
<li>To what extent has [our product or s... | g37181 | [
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<p>I am trying to manually estimate the non-seasonal components of an SARIMA (p,d,q)x(P,D,Q)[s]. I thought the estimation is going the same way like in ARIMA, but the output says somehow something different. </p>
<p>I have an autocorrelation in the acf correlogram and one significance bound at lag 1 in the pacf. That ... | g63727 | [
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<blockquote>
<p>"The set of points in $\mathbb{R}^2$ classified ORANGE corresponds to
{$x:x^Tβ>0.5$}, indicated in Figure 2.1, and the two predicted classes
are separated by the decision boundary {$x:x^Tβ=0.5$}, which is linear
in this case. We see that for these data there are several
misclassifications o... | g63728 | [
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<p>I'm testing the hypothesis that there's a monotonic relationship between two variables. I think I should use a Spearman rank correlation test, since my data don't necessarily meet normality assumptions & have many outliers. However, there are many ties in the independent variable. How can I tell whether the ties... | g554 | [
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<p>Having an <strong>integer positive</strong> variable (number of days) in an experiment, I got negative values for the density plots using R. I have read other posts relating to this topic. They admitted that the experimental biases, zero values and values very close to zero are the reasons for this. Can you suggest ... | g63729 | [
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<p>I have a model that I fit on two different samples (each representing a region in a country, with different sample sizes):</p>
<pre><code>region 1: P = a1 + a2*H
region 2: P = b1 + b2*H
</code></pre>
<p>which is simply:</p>
<pre><code>region 1: R1 <- lm(P ~ H)
region 2: R2 <- lm(P ~ H)
</code></pre>
<p>T... | g650 | [
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<p>I'm not sure if I fully understand the meaning of the symbol, I've seen this symbol in various articles but haven't managed to understand what they implied.
I did some reading and it looks like $A \sim B$ means B-Distribution of random variable $A$.</p>
<p>Then how would it apply in continuous case as this
$$\epsi... | g21536 | [
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-0.0027... |
<p>I have two groups of subjects, both undergoing two experimental conditions. During the experimental conditions, the subjects take questionnaires for evaluation of the mood states, and blood pressure is measured at the same time. </p>
<p>I want to obtain the correlation between blood pressure and the mood ratings, w... | g63730 | [
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<p>My question is triggered by a question that was asked on stackoverflow: <a href="http://stackoverflow.com/questions/12198115/using-different-metric-for-hclust-linkage">http://stackoverflow.com/questions/12198115/using-different-metric-for-hclust-linkage</a>.</p>
<p>The thing is this: </p>
<p>I can formulate an alg... | g63731 | [
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<p>I have a set of data $Y \in \mathbb{R}^n$ and a set of $k$ factors $\{F_1, ..., F_K\}$ with $F_i \in \mathbb{R}^n ~ \forall i$.</p>
<p>I would like to perform a factor analysis which consits in finding $\beta \in \mathbb{R}^k$ such that:</p>
<p>$$Y_t = \alpha + \sum_{i=1}^k \beta_i {F_i}_t + \varepsilon_t$$</p>
... | g21541 | [
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<p>I am doing some work on the effects of collinearity on different types of model (OLS, binomial logistic, ordinal logistic, multinomial logistic and maybe others). I have found the perturb package in R, which will be very useful for this. This package shows how small changes in the data affect the parameter estimates... | g63732 | [
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0.04... |
<p>I studied the standard econometrics textbooks about panel data, but most textbooks only mention the difference between balanced and unbalanced panels. The advantage of having balanced panel data is not usually explained. I would like to know: <strong>What is the advantage of having a balanced panel?</strong> I belie... | g63733 | [
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<p>This might be a simple question but I am unable to find a solution on the web. I would like to measure variation of some numerical data. What is the minimum number of values I should use for measuring their standard deviation or coefficient of variation? Basically my plan is to derive groups from a set of performanc... | g319 | [
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0.00012521630560513586,
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<p>I am performing a Mixed between subjects Anova where I have multiple time points that subjects have completed a measure at. </p>
<ul>
<li>The within subjects factor is time. </li>
<li>The between subjects factors include gender, ethnicity, refugee status and English language. </li>
</ul>
<p>My two questions are</p... | g63734 | [
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0.02109929546713829,
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0.022278498858213425,
... |
<p>I am wondering how the probabilities of the observation nodes in dynamic Bayesian networks are set.</p>
<p>I want to know whether the probabilities are monitored or are given by sensors?</p>
<p>So, what does the term <code>observation nodes</code> actually mean, and from what can I compute their probabilities?</p... | g21543 | [
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0.024602849036455154,
0.04336358606815338,
0.0... |
<p>Lots of distributions have "origin myths", or examples of physical processes that they describe well:</p>
<ul>
<li>You can get normally distributed data from sums of uncorrelated errors via the Central Limit Theorem</li>
<li>You can get binomially distributed data from independent coin flips, or Poisson-distributed... | g63735 | [
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<p>Let there be observed data points $X = {X_1.. X_n .. X_N}$, where each $X_n \in R^D$. Lets assume these are distributed as a Gaussian $X \cong \mathcal N(\mu,\Sigma)$. Let us also assume that the mean has a Normal prior and covariance has Inverse Wishart prior. Since these are conjugate priors, given observed data $... | g21545 | [
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0.03058589994907379,
0.020678767934441566,
-0.005... |
<p>I have multiple measures from a scale and I want to determine the best factorial structure using EFA, in SPSS. I don't understand if I can retain the number of factors that I want to retain because they seem to be the most theoretically valid, or if I must keep the number of factors the program gives me based on Kai... | g40927 | [
0.0640387088060379,
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0.017395395785570145,
0.0019797300919890404,
0.030168883502483368,
0.000... |
<p>I have a data set where I am trying to compare a difference of means between two different samples. However, I do not have the standard deviation of the mean for each sample.</p>
<p>The sample data consists of a date, a number of visits, and a total number of times the event of interest. For each visit, the event o... | g43473 | [
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0.011476056650280952,
0.043533872812986374,
0.01767788641154766,
... |
<p>Let's say I have two predictors to predict financial risk: Gender and shopping habits. Gender has levels of "Male" and "Female", while shopping habits has "quick shopper" and "slow shopper". </p>
<p>I am quite surprised to see this: When I split the population into "male" and "female", shopping habits as a single v... | g63736 | [
0.029063565656542778,
0.03211357444524765,
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0.003599660936743021,
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0.01593027077615261,
-... |
<p>I am having a problen in preparing my data.
The data is a GPS track recorded from a lengthy car-trip. This is recorded with a constant frequency - I have a datapoint every 200ms.
Now I have calculated the distance that was travelled up to each point.</p>
<p>What I want now, is to interprete the distance as time ba... | g21548 | [
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0.015272027812898159,
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0.008603324182331562,
0.04333963990211487,
... |
<p>Who said: </p>
<blockquote>
<p>"Let the Data Speak for Themselves" </p>
</blockquote>
<p>-- Ronald Fisher or John Tukey?</p> | g14408 | [
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0.0146078085526824,
0.005040287505835295,
0.0014... |
<p>In <em>k-means clustering</em> we initially pick $k$ random centroids and assign the given data to one of these $k$ centroids (which ever is nearest). After this we create new centroids by taking the mean of the assigned points. </p>
<p>However there might be case that the initially selected random centroids may no... | g21550 | [
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0.0039793276228010654,
0.03854981064796448,
0.051318101584911346,
0.... |
<p>Are these conditions sufficient for asymptotic normality of MLE? If it is, pls. let me know the references.</p>
<p>1-First and second derivatives of $\ell(\theta,\eta)$ are defined.
2- The Fisher information matrix be non-singular and continuous with respect to the parameters $\theta$ and $\eta$.</p> | g63737 | [
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0.038135137408971786,
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0.0214765015989542,
0.05644228681921959,
0.0297... |
<p>Can I run simple linear regression on SPSS between continuous outcome such as exam results and a dichotomous predictor such as smoking or not (0 and 1).</p> | g21552 | [
0.020670421421527863,
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0.05742308124899864,
-... |
<p>Assuming that each flight is independent of the others, and each flight has a probability of $10^{-9}$ of crashing independent of other flights, how many flights are needed for the probability of the aircraft crashing at least once to reach $0.01$.</p>
<p>I'm trying to use this:</p>
<p>$0.01=\left(\array{n\\1}\rig... | g63738 | [
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0.010243061929941177,
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-0.009326223284006119,... |
<p>I have a data set where samples are collected once per year for 15 years at a number of sites. I am worried that these data are temporally autocorrelated and was trying to figure out if I need to address that. However, the only time I will be using degrees of freedom with these data is in a perMANOVA. This test calc... | g63739 | [
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0.02796427719295025,
0.02788352407515049,
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0.0... |
<p>In Neural Nets for the regression problem, we rescale the continuous labels consistently with the output activation function, i.e. normalize them if the logistic sigmoid is used, or adjusted normalize them if tanh is used. At the end we can restore original range but renormalizing the output neurons back.</p>
<p>Sh... | g63740 | [
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0.001653976971283555,
-0.0022955569438636303,
0.09479209780693054,
0.026618702337145805,
-0.0... |
<p>I have the following observations</p>
<p>Oberservation ; Count </p>
<p>-1.67 ; 726 </p>
<p>18.33 ; 33</p>
<p>148.33 ; 15</p>
<p>This is obviusly not normal distributed :S</p>
<p>How can I make a test for $H_0: \mu = 0$ or even better is it possible to make a confidence interval for the mean?</p> | g63741 | [
0.019678018987178802,
0.010932555422186852,
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0.013896702788770199,
0.04557233676314354,
0.014285965822637081,
-0.016... |
<p>I have 8 parameters with 3 levels and the number of tests required to study this case is 27. </p>
<p>Can I generate polynomial regression model to describe interaction of these parameters?</p> | g63742 | [
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0.007603340782225132,
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0.010065611451864243,
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0... |
<p>I got stuck with this, I will appreciate a lot any help. I need to make an R program in order to run this algorithm (in the photo below), with simulated data. The question is to use the method of composition to sample from a t-distribution via sampling normal distributions.</p>
<p><img src="http://i.stack.imgur.com... | g21559 | [
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0.042293377220630646,
0.004878393840044737,
0.04259878024458885,
0.043072640895843506,
0.... |
<p>I'm attempting to perform hierarchical agglomerative cluster analysis in R. </p>
<p>However, when I use particular clustering methods, I get reversals (upward branching) in the resulting tree, which violates the ultrametric property.</p>
<p><img src="http://i.stack.imgur.com/WSPo2.jpg" alt="enter image description... | g37653 | [
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0.0387287363409996,
0.016038285568356514,
0.03784981369972229,
0.03405626863241196,
0.008657272905... |
<p>I have a question regarding the appropriate use of comparisons for independent samples (3 factor levels). Overall sample size is N=546, subsamples: 218 or 228 or 100), convenience sampling, stratified.</p>
<p>I use ANOVA with post hoc Tukey, if Levene indicates variance homogeneity.</p>
<p><strong>My question: If ... | g63743 | [
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0.011427124962210655,
0.016008218750357628,
0.00196489947848022,
-0.0174148827791214,
0.0238... |
<p>$2^{5-2}$ Design </p>
<p>Design Generators: $D=AB\quad E=AC$ </p>
<p>Defining Relation: $I=ABD=ACE=BCDE$</p>
<p>$$\text{Aliases}$$
$$A=BD=CE=ABDE$$
$$B=AD=ABCE=CDE$$
$$C=ABCD=AE=BDE$$
$$D=AB=ACDE=BCE$$
$$E=ABDE=AC=BCD$$
$$BC=ACD=ABE=DE$$
$$CD=ABC=ADE=BE$$
But the alias structure in the book <code>Design and Ana... | g21563 | [
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0.03035622276365757,
0.02130468748509884,
0.050202514976263046,
0.0... |
<p>Some predictive modeling techniques are more designed for handling continuous predictors, while others are better for handling categorical or discrete variables. Of course there exist techniques to transform one type to another (discretization, dummy variables, etc.). However, are there any predictive modeling tec... | g105 | [
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0.03886884078383446,
0.00... |
<p>I am analyzing offender recidivism data using survival analysis. In particular, I am looking at the risk of getting arrested as a function of employment.
When I treat employment as a time-varying covariate, it is associated with a 21%
reduction in the risk of recidivating. However, if employment is included without
... | g63744 | [
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0.03474944829940796,
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0.... |
<p>I have random sets of $N$ random 32-bit strings,
where all bits are i.i.d. with $\mathbb{P}(0) = \mathbb{P}(1) = 1/2$.
Define<br>
$\ \ \ \ $weight( 32-bit x ) = number of 1 bits in x, i.e. Hamming distance to 0<br>
$\ \ \ \ $minweight( set $X$ ) = min$_{\text{x} \in X}$ weight( x )</p>
<p>How does the average minwe... | g40952 | [
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-0.04565899446606636,
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0.06813620030879974,
-0.003554037306457758... |
<p>Using the following data, I need to determine if, independent of mass, the observed response is associated with sex, location, and/or age</p>
<pre><code>example<- data.frame(response=c(2.401,2.588,2.293,2.880,2.655,2.830,3.165,2.665,3.126,2.973,1.725,1.889,2.631,1.750,2.271,2.347,2.173,1.962,1.599,2.297,1.894,2.... | g63745 | [
0.011684690602123737,
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0.06459758430719376,
0.0... |
<p>Just about every matrix factorization (e.g., SVD++) has some matrix that includes a n users and m (e.g.,) ratings. </p>
<p>Here is my question, how do you include information like demographic information, information on what the user has said about a product (like, "it's cheesy", or "awesome!"). </p>
<p>What I'm r... | g63746 | [
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0.0785348191857338,
... |
<p>I have used a Box-Behnken experimental design. I have a full quadratic model. </p>
<p>However, I had to transform the response, $Y$ for the model to fit; I did this using a Box-Cox transformation with $\lambda=0.5$. </p>
<p>For example, one of the regressions is like this:</p>
<p>$$Y = 1.28 - 0.008X_1-0.025X_2-0.... | g49681 | [
0.013740417547523975,
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-0.... |
<p>I'm reviewing a paper which has the following biological experiment. A device is used to expose cells to varying amounts of fluid shear stress. As greater shear stress is applied to the cells, more of them start to detach from the substrate. At each level of shear stress, they count the cells that remain attached, a... | g21566 | [
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<p>Could you kindly let me know if it is possible to print parameters to the console as they are being optimized (using the levenberg marquardt algorithm) in python/matlab? I have been trying to do so but to no avail. I would need to modify the printed parameters before supplying them into the algorithm before proceedi... | g63747 | [
0.07944430410861969,
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0.04134554788470268,
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0.040623780339956284,
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0.061... |
<p>How do I estimate parameters of subpopulations in a 1D gaussian mixture model when I already have density (measured on a grid) of the mixture?</p>
<p>All the algorithms I can find (like the well-known EM algorithm) assume that only samples from the mixture are available. My experiment directly yields density values... | g63748 | [
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... |
<p>I'm analyzing customer satisfaction for a certain program. My response variable is ordinal- where 0 means dissatisfied and 1 means satisfied. I have 10 predictor variables. I used Binary logistic Regression on my data, and the results showed that 6 of my 10 variables are statistically significant.
My question is, w... | g21567 | [
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0.021989017724990845,
... |
<p>I have some spatial data and I want to fit a correlation function may be exponential or gaussian to my data. I could calculate the correlation for different pairs of my spatial point to get some empirical correlation function. What is the best way to fit some standard correlation functions to my empirical one.</p>
... | g63749 | [
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<p>I have come across an industry example of a simple linear regression ($y=a+bx+\epsilon$) where the slope coefficient has been adjusted by the mean of $y$ ($b/\text{mean}(y)$) and described as a "slope impact". The exact interpretation that they use is that this slope impact represents "the percentage change in $y$ ... | g63750 | [
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<p>Can someone help me identify what statistical method (or any method) that I can use to correlate the effects of natural disasters on Stock Market Index? </p> | g63751 | [
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<p>I'm running an experiment where subjects are viewing a stimulus, and they have to decide if the stimulus is brighter/darker/identical in respect to a standard image.
Stimulus luminosity actually varies, and it can be brighter, darker or identical to the standard. What i' triyng to estimate is the threshold (or the j... | g63752 | [
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<p>I have 5 quantitative predictor variables in my logit model, and when I use the <code>cor</code> function in R on those 5 variables, I see that $x_{1}$ and $x_{2}$ have correlation coefficient $r_{12}=0.718$ and $x_{3}$ and $x_{4}$ have $r_{34}=0.654$. The VIF values are all less than or equal to 2. So does this sug... | g63753 | [
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... |
<p>I have a group of data with 12 different football players, and they are rated for 11 different skills (speed, skill, flair, etc).</p>
<p>I am looking to pair up individuals based on similar footballers, and was thinking of just taking the average for each player and matching them up.</p>
<p>Does anyone have any be... | g40957 | [
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-... |
<p>I have multiple models that I'm training using <code>train</code> in the <code>caret</code> package, all while using the same cross validation folds to compare their performance. I'd like to use glmnet via caret's <code>train</code> and specify the sequence of lambda values by obtaining them like how the <code>cv.gl... | g63754 | [
0.007036828435957432,
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0.05245238170027733,
... |
<p>I have data from 3 groups of algae biomass ($A$, $B$, $C$) which contain unequal sample sizes ($n_A=15$, $n_B=13$, $n_C=12$) and I would like compare if these groups are from the same population.</p>
<p>One-way ANOVA would definitely be the way to go, however upon conducting normality tests on my data, heteroskedas... | g63755 | [
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0.011874961666762829,
0.028029339388012886,
0.026422059163451195,
-0.005094578023999929... |
<p>Say that I have your standard PID controller at work. To keep it extremely simple imagine I have a target $x^*$ on the variable $x$. Then the controller is:</p>
<p>$y(t) = K_p ( x^* - x_t) + K_i \int_0^t (x^* - x_{\tau})d \tau + K_d \frac{d}{dt} (x^* -x_t)$</p>
<p>Now, I do have numerical observations for all $t \... | g21576 | [
0.02196374535560608,
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0.0... |
<p>I am trying to detect anomalous values in a time series of climatic data with some missing observations. Searching the web I found many available approaches. Of those, stl decomposition seems appealing, in the sense of removing trend and seasonal components and studying the remainder. Reading <a href="http://cs.well... | g63756 | [
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0.... |
<p>Hi I'm quite new to this and I'm playing around with R and Microsoft's SSAS. Does anyone have a rule of thumb how big a data set has to be for association rules and decision trees to be statistically valid. In uni our assignments use data sets with about a 1000 in. </p> | g21578 | [
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0.019341... |
<p>in order to rectify invalid t-stats because of autocorrelation in Difference-in-Differences (DnD) models, Duflo et al (2004) propose (among other solutions) to collapse data so as to have a before-after DnD. My question: What if we already HAVE a before-after setting (e.g. pre-reform vs post-reform)? Would it be sti... | g21579 | [
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0.009153163060545921,
0.019420316442847252,
0.0006977595039643347,
0.08319998532533646,
... |
<p>I have this problem:</p>
<pre><code>A Ph.D. graduate has applied for a job with two
universities: A and B. The graduate feels that she has a
60% chance of receiving an offer from university A and a
50% chance of receiving an offer from university B. If
she receives an offer from university B, she believes that ... | g21582 | [
0.010506453923881054,
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0.029868414625525475,
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0.026378214359283447,
0.007585983257740736,
0.05202849954366684,
0.03727344051003456,
0.000462... |
<p>I know that I can perform a stepwise selection on ordinary linear regression model based on the t-value.</p>
<p>but what about Negative Binomial regression model - or GLM in general? Does it theoretically make sense to perform a stepwise selection on variables bases on P-value resulting from "z-scores" when I am tr... | g63757 | [
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<p>I have realized a multiple linear regression with R.
When I realize the graphs diagnostics, I would like to draw the confidence band along with the loess curve in the first plot (residual vs. fitted values).</p>
<p>How can I do that with R (R codes) ?</p>
<p>Best,</p> | g63758 | [
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0.007823481224477291,
0.041580680757761,
0.04070406034588814,
0.010... |
<p>Suppose I measure reaction time of 4 students, initially before any treatment, then after treatment 1, and finally after treatment 2. (Note all treatments will eventually be applied to all students.)
Also because of potential error with reaction time measurements, suppose 3 trials are done for each student-treatment... | g21585 | [
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0.021732931956648827,
0.005663692951202393... |
<p>I have run a lasso regression on a dataset of 100 observations and 80 variables (using 10-fold cross-validation to find the minimum lambda subsequently used in the final model). The lasso regression found approximately 40 of the variables to have non-zero coefficients.</p>
<p>I wanted to check my model and therefor... | g21586 | [
0.026552239432930946,
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0.000... |
<p>In the palaeoclimate world, palaeoecologists have used spatial training sets of say sea-surface temperture (SST) and related this to micro-organisms living at the locations where SST was measured. A popular model to predict SST from species assemblages (so you can count the same species from sediment core and thus p... | g63759 | [
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0.04878169298171997,
0.048998329788446426,
0.027445750311017036,
0.06283236294984818,
0.015099... |
<p>Assume I have a distribution governing the possible outcome from a single random variable X.
This is something like [0.1, 0.4, 0.2, 0.3] for X being a value of either 1, 2, 3, 4.</p>
<p>Is it possible to sample from this distribution, i.e. generate pseudo random numbers upon each of the possible outcomes given the... | g63760 | [
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0.004898932762444019,
-0.002488705795258... |
<p>Why is the MA(1) process phrased as $X_t = \epsilon_t + \theta\epsilon_{t-1}$, with the $\epsilon_t$ defined as the (unobserved) errors between model fit $\hat X_t$ and observed $X_t$?</p>
<p>Why is the MA formulation preferable to the more simple alternative (without unobservables) $X_t = \eta_t + \theta\eta_{t-1}... | g63761 | [
0.040654584765434265,
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0.01915346272289753,
0.013202371075749397,
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0.11115328967571259,
0.04583... |
<p>Here is a list of logistic regression coefficients (first one is an intercept)</p>
<pre><code>-1059.61966694592
-1.23890500515482
-8.57185269220438
-7.50413155570413
0
1.03152408392552
1.19874787949191
-4.88083274930613
-5.77172565873336
-1.00610998453393
</code></pre>
<p>I find it weird how the intercept is so... | g21590 | [
-0.0016493515577167273,
-0.06672710925340652,
0.00866439938545227,
-0.031787894666194916,
0.08536578714847565,
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0.05185304954648018,
0.07433737814426422,
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0.07085014134645462,
0.03899456560611725,
-0.0209... |
<p>Concentrations of 50 proteins were measured in 50 normal persons and 150 patients. I am just wondering what kind of analysis will be most appropriate to finding out which protein concentration is most different.</p> | g37654 | [
0.021725140511989594,
0.02148466743528843,
0.01123630627989769,
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0.019532689824700356,
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0.014021509326994419,
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... |
<p>I'm curious whether something I tried makes sense statistically...</p>
<p>I took a pile of time series inputs and performed an SVD. I want to predict variable Y on the basis of its own time series, and the first 50 <code>SVD$u</code> factors as external regressors.</p>
<p>It looked like an ARIMA(2,2,2) was a good... | g63762 | [
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0.004449706524610519,
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0.03906721621751785,
0.03189026936888695,
0.09668188542127609,
... |
<p>I want to divide $2n$ objects into $n$ pairs according to the Euclidean distance between them, however, I am not sure which algorithm I should use. Should I use one of matching algorithms?</p> | g63763 | [
0.010612296871840954,
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0.012184705585241318,
0.0008313886937685311,
0.002158819232136011,
0.012721960432827473,
0.017625639215111732,
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-0.013921278528869152,
... |
<p>I have two datasets a training and a test dataset. The dependent variable is a proportion and there are 54 predictors which are positive and negative real numbers and another 7 predictors that are text. </p>
<p>There are three response variables. Total the normalized total number of hits. Treatment the normalized t... | g45752 | [
0.008434545248746872,
-0.06776077300310135,
-0.009526810608804226,
-0.07604353129863739,
0.0007915783207863569,
-0.005442599765956402,
-0.011028586886823177,
0.009303274564445019,
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-0.04279892519116402,
0.015986427664756775,
-0.03380768001079559,
0.008409369736909866,
... |
<p>What are some examples of less common transformations or basis expansions that have been applied to a set of input variables to build a more complex linear regression model? </p>
<p>For example, a "common" transformation might be to include a set of interaction predictors; a "less common" transformation might be t... | g63764 | [
-0.016531091183423996,
-0.018245652318000793,
0.006961354520171881,
-0.05865558609366417,
0.001954782987013459,
-0.06624951213598251,
0.02809826098382473,
0.03646200895309448,
0.022708214819431305,
-0.016906166449189186,
0.023645631968975067,
-0.011586588807404041,
0.06876187026500702,
-0.... |
<p>Suppose that an urn contains a number of black and a number of white balls, and suppose that it is known that the ratio of the numbers is $\,3\mathbin{:}1\,$ but that it is not known whether the black or the white balls are more numerous. Find the estimator of the probability of drawing a black ball.</p>
<p>I have ... | g63765 | [
0.002606106223538518,
-0.009293044917285442,
0.00024182716151699424,
-0.0458965077996254,
0.03882068768143654,
-0.0224789809435606,
0.014251742511987686,
0.019313443452119827,
-0.02048378810286522,
-0.013105959631502628,
-0.04434853419661522,
-0.020807484164834023,
0.07561656832695007,
-0.... |
<p>I have a 70K x 30 dataset and I want to build a regression model on it. Right now, I am running a bunch of algorithms via Weka tool with cross-validation and I compare the RMSE values reported by Weka in order to decide which model works better.</p>
<p>However, after I experiment with Multi layer perceptron, Linear... | g63766 | [
0.028858566656708717,
-0.07191523164510727,
-0.010000621899962425,
-0.010101637803018093,
-0.007431381847709417,
-0.028500664979219437,
0.03159800544381142,
0.012010455131530762,
-0.03197729215025902,
-0.015085629187524319,
0.05690942704677582,
0.024190129712224007,
0.06287238746881485,
0.... |
<p>I would appreciate if someone could help me write the mathematical equation for the seasonal ARIMA (0,2,1) x (0,0,1) period 12. I'm a little confused with how to go about this. I would prefer an equation involving $Y_{t}$ , $e_{t}$, $\theta$ and $\Theta$. </p>
<p>I really don't want an equation involving the backsh... | g49885 | [
0.014126382768154144,
0.01765264943242073,
0.00020468267030082643,
0.0748012438416481,
0.0014595537213608623,
-0.02618057280778885,
0.04982147365808487,
0.015528152696788311,
-0.0004656868986785412,
0.008798398077487946,
-0.009131252765655518,
0.07982558012008667,
0.05390268564224243,
-0.0... |
<p>I have 30 features in my self-collected dataset where I want to build a regression model. When I look at my data, most of the attributes (95% of the data points) are skewed on a very small range. Out of 30 features, only 2 features has sort-of normal distribution and other features are ranged within a majority range... | g21600 | [
0.008465754799544811,
-0.01635054498910904,
0.006906263530254364,
-0.01363347563892603,
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0.003358761314302683,
0.00522809661924839,
-0.04842869192361832,
-0.000646578730084002,
0.04903849959373474,
0.04567781835794449,
0.0024719417560845613,
-0.0... |
<p>I am trying to fit a logistic regression model with L1 regularization on my data. My data has just 12 examples with 150 features. So I used L1 regularization. Now when I use the <a href="http://www.mathworks.fr/fr/help/stats/lasso-regularization-of-generalized-linear-models.html" rel="nofollow">lassoglm</a> function... | g63767 | [
0.04668353497982025,
-0.00689022708684206,
0.002440765732899308,
-0.016076957806944847,
0.017324166372418404,
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0.031013494357466698,
0.05033788084983826,
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-0.031907472759485245,
-0.006737525574862957,
0.016305837780237198,
0.07478136569261551,
0.00... |
<p>I have a question regarding model comparison using Bayes factors. In many cases, statisticians are interested on using a Bayesian approach with improper priors (for example some Jeffreys priors and reference priors). </p>
<p>My question is, in those cases where the posterior distribution of the model parameters is ... | g63768 | [
0.03966823220252991,
-0.05084966868162155,
0.0445883609354496,
-0.028645141050219536,
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-0.0034762565046548843,
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0.009450807236135006,
0.0392577163875103,
0.03947538137435913,
0.00032403322984464467,
0.... |
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