question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am learning some image processing stuff and equalizing a histogram comes up as an important topic. I have followed the procedure listed on Wikipedia but the resulting equalized histogram does not look much better to me.</p>
<p>Let's say I have the following histogram where values only range from 0 to 7:</p>
<pr... | g62086 | [
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<p>Robby McKilliam says in a comment to <a href="http://stats.stackexchange.com/a/56/11697">this</a> post:</p>
<blockquote>
<p>It should be pointed out that, from the frequentists point of view, there is no reason that you can't incorporate the prior knowledge into the model. In this sense, the frequentist view is s... | g62087 | [
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<p>I have estimated (MC simulated) some probability values <strong>y</strong>, that each depends on a value of <strong>x</strong> between 0 and 1. </p>
<p>Say, for instance, that the vector <strong>x</strong> contains</p>
<p>$x_{1} = 0.1,\ \ x_2 = 0.2,\ \ x_3 = 0.3,\ \ x_4=0.4,\ \ x_5 = 0.5,\ \ x_6 = 0.6,\ \ x_7 = 0.... | g62088 | [
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<p>Say I have the centroids calculated via kMeans, and clusters identified.</p>
<p>How do I take an incoming datapoint ( a row in matrix with all the features) to compare with the points and figure out which cluster the datapoint belong to?</p>
<p>How to design a runtime like this?</p>
<p>I assume we only have to ca... | g62089 | [
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<p>I am trying to conduct a simulation study on a variation of the kernel density estimator. In that experiment, there is a parameter in one of my formulas that involves the value of the unknown pdf at a given point x. Therefore I need to find a consistent estimator to estimate the value of f(x), but I have no clues on... | g19012 | [
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<p>I work for a financial planning company and what I am trying to do is to project a client’s investment assets forward over several years. This is easy if we assume a constant return e.g. 7% every year. However I want to take account of fluctuations of returns and have therefore built in some random returns using e... | g19017 | [
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<p>Going through the <a href="http://en.wikipedia.org/wiki/Phi_coefficient" rel="nofollow">Wiki article</a> on the Phi coefficient, I've noticed that for paired binary data "a Pearson correlation coefficient estimated for two binary variables will return the phi coefficient".</p>
<p>Upon running a quick simulation I f... | g19018 | [
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<p>As far as I can understand, the Daniell kernel, is simply $K(j/M)=\frac{1}{2M+1}1(|j|\leq M)$. </p>
<p>Namely, this is a two sided average. Why do people call this an untruncated kernel and differentiate it from a kernel of the form $K(j/M)=1(|j|\leq M$) when the only thing different is the scaling factor?</p> | g19021 | [
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<p>I am going to run a quantitative experiment but I need my participants to come over and do some tasks in front of me. since I cannot recruit more than 40 participant (economic issues) and at the same time I need several data, I am going to ask each participant to go through the same task with different inputs. For e... | g19022 | [
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<p>In <code>R</code> we can "prior weight" a <code>glm</code> regression via the <strong><em>weights</em></strong> parameter. For example:</p>
<pre><code>glm.D93 <- glm(counts ~ outcome + treatment, family = poisson(), weights=w)
</code></pre>
<p>How can this be accomplished in a <code>JAGS</code> or <code>BUGS</c... | g62090 | [
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<p>I am having a little trouble coming up with a way of analyzing my data. If there is a short answer (i.e., "use logistic regression, dummy") you can just post that and I'll do some digging on my own - I just need to be pointed in the right direction...</p>
<p>My independent variable is a count and my dependent varia... | g62091 | [
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<p>I have a ROC curve generated for a multivariate logistic regression. Does it look correct?</p>
<p>This is what I've done:</p>
<ol>
<li>Solve $\theta_0 + \theta_1X_1 + \theta_2X_2 ... = Y$ for the $\theta$s</li>
<li>Iterate over all the input $X_i$ and compute the predicted $Y_i'$ for various cutoff values (thresho... | g62092 | [
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<p>I want to perform factor analysis to reduce the number of variables in my dataset (the variables are very redundant). One of the parameters I need to supply to the R code is the number of factors to retain. In order to choose this number, I intend to try several numbers and evaluate the best number on a training set... | g62093 | [
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<p>I have the frequencies of binary patterns of polar and non-polar residues in strands of anti-parallel beta-hairpins from 5 different sets of anti-parallel beta-hairpins. I want to know how can I quantify the similarity or difference between the frequencies of binary patterns among those 5 sets of beta-hairpins. Are ... | g62094 | [
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<p>I conducted a survey to get peoples current moods with the activity they were just doing and if they did it with a friend or not. I've only studied how to linear regression, and may have gotten over my head in doing this, but I was wondering what you would use if you have ordinal numeric values with categorical data... | g41845 | [
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<p>I am using logit models to predict whether or not children are unhealthy (binary indictor). Many of my models have statistically significant relationships between predictors of interest (ie, if the child’s household has improved water/sanitation) and the outcome. However, none of my models outperform a model whic... | g62095 | [
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<p>I have 10 vectors each having 100,000 points ( Muscle activity obtained by sampling at a rate of 10 Khz). I take integral of each data set to have 10 values. I want to know whether these 10 values are normally distributed. ?</p> | g49049 | [
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<p>Referring to the <a href="http://stats.stackexchange.com/a/9144/46297">link</a>, my doubt is regarding the actual computation of variance of the forecast. The variance depicted here is $\sigma^2 [1+X^*(X'X)^{-1}(X^*)']$. As mentioned in the link added here, if $X$ is a row vector, then $X'X$ will be a singular matri... | g62096 | [
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<p>I wonder if there is a clear-cut difference between the so-called zero-inflated distributions (models) and so-called hurdle-at-zero distributions (models)? The terms occur quite often in the literature and I suspect they are not the same, but would you please explain me the difference in simple terms? </p> | g62097 | [
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<p>I have the model $y_i=\beta_1+\beta_2 X_i+ u_i$ where $u_i\sim\text{iid } N(0,\sigma^2)$. I estimate $\beta_1$ and $\beta_2$ by drawing a straight line between the first $(x_1,y_1)$ and last dot $(x_n,y_n)$. So, $\hat{\beta}_2$ will be the slope of this straight line.</p>
<p>What is the variance of $\hat{\beta}_2$ ... | g62098 | [
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<p>I have pairs of values from two runs (replicate) for each sample along with total count for each run. I assumed each value as random binomial. I used log-likelihood ratio test to compare each pair, but my data range is wide, e.g. X1, X2 = (0,0), (0,1), (0,2), ..., (20, 20) with total counts for each run (n1, n2) ran... | g62099 | [
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<p>Is there any software package to solve the linear regression with the objective of minimizing the L-infinity norm.</p> | g62100 | [
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<p>I'm regressing a continuous variable (y) on a categorical (x=0,1,2) variable.
Is it possible (or even make sense?) to derive an elasicity of y on x?
Thanks.</p> | g19033 | [
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<p>To compare distributions, it is common to use box blots.</p>
<p>I'm looking for a similarity measure that calculates whether distributions are
the similar or not.</p>
<p>Ideally, given that e.g. four distributions are exactly the same,
it would return 1.
The more they are different, it would approach to 0.</p>
<p... | g19034 | [
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<p>I have a table with responses of a survey. Now I want to test the statistical significance between 3 groups of respondents. </p>
<p>There are two columns I'm interested in. The first is an ordinal variable denoting company size (small, medium, large). The second is a 5-scale Likert variable denoting working experie... | g62101 | [
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<p>For a Gaussian linear model $Y=\mu+\sigma G$ where $\mu$ is assumed to lie in some vector space $W$ and $G$ has the standard normal distribution on $\mathbb{R}^n$, the statistic of the $F$-test for $H_0\colon\{\mu \in U\}$ where $U \subset W$ is a vector space, is an increasing one-to-one function of the <em>devianc... | g19036 | [
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<p>While I am having a series of regression experiments, I could detect there are 2 independent variables seem to follow power law distribution.(Or, they have too much value of 1) here's a example of them.<img src="http://i.stack.imgur.com/QZAxh.jpg" alt="enter image description here"></p>
<p>Actually I did not think ... | g62102 | [
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<p>How can I transform a variable (non linear transformation) such that its values are more evenly spread, that is reduce the peak in the middle of the histogram and move more into tails?</p> | g62103 | [
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<p>I was wondering if the following is correct. I am trying to wrap my head around testing time series for stationarity, but the lecture notes I am given are rather minimal. With external sources, I think I understand the concept, but was wondering if someone could please confirm that my thinking is correct. </p>
<p><... | g62104 | [
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<p>I am looking for dynamic time warping step pattern (<a href="http://cran.r-project.org/web/packages/dtw/index.html" rel="nofollow">dtw package</a> for R) , which would allow assignment of one query index value to several reference index values (<code>symmetric2</code> does that for example). I would, however, like t... | g62105 | [
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<p>I was working on image processing where I have some list of pixel value eg:-[5,2,5,2,4,2,4,2,2,2] so I found mean as 3 and variance as 1.77778 </p>
<p>My question is how to find the probability of data been distributed eg
if data is [1,1,1,1,1] then the probability should be 1 , if data is [1,2,3,4,5,6,7,8] then th... | g62106 | [
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-0.04422128200531006,
-0.04202236980199814,
-0.021443694829940796,
0.024146035313606262,
0.040988337248563766,
0... |
<p>I am a beginner with BUGS/JAGS and I was hoping to gather the opinion of you, experts.</p>
<p>I am trying to implement a Nominal Item Response Analysis (Polytomous, not ordered, like a multiple-choice exam) with JAGS. I simulated data according to this model, but
the code doesn't seem to work as it can't recover t... | g62107 | [
-0.02130967192351818,
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0.024198491126298904,
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0.04203038662672043,
... |
<p>I've performed a study which yielded (?) the following results:</p>
<pre><code>- no bike box bike box % change
correct procedure 173 55 -27%
incorrect procedure 68 50 69%
</code></pre>
<p>Since a result could only be one of the two -... | g62108 | [
0.013109367340803146,
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0.04181298613548279,
0.0054... |
<p>I have two data sets with about 7 points on each. Excel gives me trendlines with the following values:</p>
<p>$y=0.0263x + 17.292\,,\quad R^2 = 0.09617$</p>
<p>$y= 0.0121x + 18.873\,,\quad R^2 = 0.01528$</p>
<p>What do I do with them now? How do I know if they are statistically different trends?</p> | g49346 | [
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<p>I'm trying to draw reliability conclusion about a material under a tensile test. All of my data max out the sensor. The spec is 8 lbf and I'm maxing out a 50 lbf load cell. "Get a bigger sensor" doesn't help, because I'm trying to save money by eliminating the test, not spending more (I don't really care what the... | g62109 | [
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... |
<p><strong>My question:</strong> When doing SVD analysis, you can extract the maximum contributors to each component from the V matrix - does the sign of the the component matter?</p>
<p><strong>Background</strong></p>
<p>I'm currently enjoying the Coursera class on <a href="https://class.coursera.org/dataanalysis-00... | g62110 | [
0.019530093297362328,
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0.013463099487125874,
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0.05131131038069725,
0.035364631563425064,
0.08260527998209,
0.0012... |
<p>I have an input dataset <code>x_train</code> and an output dataset <code>y_train</code></p>
<pre><code> > head(x_train)
Symscore1 Symscore2 exercise3 exerciseduration3 groupchange
1 1 0 2 3 Transitional to Transitional
2 1 ... | g62111 | [
-0.0208603423088789,
-0.0164223313331604,
0.01250729151070118,
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0.013983994722366333,
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0.0179410632699728,
0.04368579015135765,
-0.0025... |
<p>In my data, each instance has several attributes as <code>TRUE</code> or <code>FALSE</code>. For example:</p>
<pre><code>Instance1: X1=TRUE, X2=TRUE, X3=FALSE, ...
Instance2: X1=FALSE, X2=TRUE, X3=FALSE, ...
</code></pre>
<p>I need to classify a <code>TRUE</code>/<code>FALSE</code> attribute, named <code>Y</code>,... | g62112 | [
0.0500747375190258,
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0.010657516308128834,
0.005413467064499855,
0.04449494183063507,
0.03729750216007233,
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<p>Were finalizing an RCT with two intervention groups (n=13, n=11). Both samples are evaluated pre vs post treatment for pain (VAS), and also against each other (group vs group). However, there are four subjects lost to post treatment in one of the groups (n13 --> n=9).
Which statistic model/test would be appropriate ... | g62113 | [
0.000991346430964768,
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0.022460192441940308,
0.012127220630645752,
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-... |
<p>I want to conduct a usability study for a software programming tool. There are two versions of the tool (prototype A and prototype B) with different features, but allowing the same goals. I want the participants to complete a set of tasks using both versions of the tool and report the time taken. I'll compare the ti... | g62114 | [
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0.029283598065376282,
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0.0... |
<p>I have field measurements of spectral reflectance obtained for a research to map different vegatation assemblages. I have been able to use the median test and, Kruskal-wallis H test with Tukey post-hoc in SPSS to determine the vegetation assemblages with significant differences between them. However, I need to know ... | g62115 | [
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0.03824306279420853,
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0.041919492185115814,
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0.0455225333571434,
0.0595... |
<p>Before submission of my meta-analysis I want to make a funnel plot to test for heterogeneity and publication bias. I have the pooled effect size and the effect sizes from each study, that take values from -1 to +1. I have the sample sizes n1, n2 for patients and controls from each study. As I cannot calculate the st... | g49078 | [
-0.0008710437105037272,
-0.015498615801334381,
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0.021253151819109917,
0.04701031744480133,
0.03790568932890892,
0.05324113368988037,
... |
<p>I have data that map one real (float) and several nominal arguments to one real value:</p>
<pre><code>y = f(r, n1, n2, n3, n4)
</code></pre>
<p>If I check dependency of <code>y</code> on <code>r</code> (r is my real-valued variable), I see that <code>y</code> depends linearly on <code>r</code> with a lot of noise ... | g62116 | [
0.034297578036785126,
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0.0045301830396056175,
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0.0003629984857980162,
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-0.010588208213448524,
-0.018187344074249268,
0.03955969586968422,
0.016972266137599945,... |
<p>I have data with continuous class and I'm searching for good methods to reduce number of attributes. Now I'm using correlation based filters, random forests and Gram–Schmidt algorithm. </p>
<p>What I want to achieve is answer which attributes are more important/relevant to class attribute than others. </p>
<p>By ... | g19048 | [
0.034057166427373886,
-0.035270217806100845,
0.038972750306129456,
-0.01728096604347229,
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0.03320247307419777,
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0.014898547902703285,
0.040024951100349426,
0.011139004491269588,
0.07049372047185898,
0.07... |
<p>Basically what I'm wondering is how different covariance structures are enforced, and how the values inside these matrices are calculated. Functions like lme() allow us to chose which structure we'd like, but I'd love to know how they are estimated.</p>
<p>Consider the linear mixed effects model $Y=X\beta+Zu+\epsil... | g62117 | [
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0.003706989111378789,
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0.021317744627594948,
0.01062769629061222,
0.0... |
<p>Is there an analogue to the higher moment Chebyshev's inequalities in the one sided case?</p>
<p>The Chebyshev-Cantelli inequality only seem to work for the variance, whereas Chebyshevs' inequality can easily be produce for all exponents.</p>
<p>Does anyone know of a one-sided inequality using the higher moments?<... | g19049 | [
-0.0110707376152277,
0.001434994162991643,
0.00391593249514699,
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0.00855204090476036,
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0.008843855932354927,
0.0013653399655595422,
0.077845... |
<p>What is the practical way to identify the factors that create variation in a data of a dataset? What category does this question fall into? Are there a set of algorithms that can be used for this purpose? Statistical modeling solutions? I googled a lot but no go! The question is so vague that hard to find an answer ... | g19050 | [
0.017665836960077286,
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0.028558390215039253,
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0.004405237268656492,
0.024725640192627907,
0.10587397962808609,... |
<p>From <a href="http://en.wikipedia.org/wiki/Complex_normal_distribution" rel="nofollow">Wikipedia</a></p>
<blockquote>
<p>the family of complex normal distributions characterizes complex
random variables whose real and imaginary parts are jointly normal,<a href="http://en.wikipedia.org/wiki/Complex_normal_distri... | g19053 | [
0.022226344794034958,
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0.035160310566425323,
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0.025951722636818886,
0.04277259111404419,
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-0.006607194896787405,
0.005987214855849743,
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-0.01615147665143013,
-0... |
<p>I have test data where I have several large samples from discrete distributions which I am using as empirical distributions. I am wanting to test whether the distributions are actually different and what the difference in means is for those distributions which are actually different.</p>
<p>Since they are discrete ... | g62118 | [
0.00863983016461134,
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-0.0020423042587935925,
-0.023136913776397705,
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0.01591501012444496,
-... |
<p>Does the Mantel Test works with non-normal distributed samples? I couldn't find anything clear enough about it.</p> | g62119 | [
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... |
<p>For simple random sampling, I know that the probability of each point being part of the sample should be equal. Also, any sample of size say $k$ should be equally likely. In the sampling procedure I am using right now, the probability of each point being part of the sample comes out to be the same. However, if a poi... | g62120 | [
0.04001561552286148,
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0.017372598871588707,
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0.011704720556735992,
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0.0028749804478138685,
0.05259259417653084,
... |
<p>I have run correlation tests between two city-level variables (e.g. weather and revenue) from about 30 different cities, and therefore got <strong>30 pairs of correlation and T-value</strong> by cities. My hypothesis is that the correlation between the two variable is determined by their geographical location, and i... | g19057 | [
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0.004645534325391054,
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0.033379510045051575,
0... |
<p>Consider the following data about bulb failures (which require a filament replacement for repair) compared across three companies:</p>
<pre><code> P(1st failure) | P(2nd failure | 1st failure) | P(3rd failure | 2nd failure)
-----------------------------------------------------------------------------------... | g62121 | [
0.06952033936977386,
-0.025548653677105904,
0.000993730267509818,
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0.05290079861879349,
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-0.0036350111477077007,
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0.027543509379029274,
0.022671421989798546,
0... |
<p>I'm analyzing a data set that has an extremely long tail, and I'm looking for a way to transfer the data into a bell curve so I can apply statistical analysis to it. Hope this makes sense, any help would be greatly appreciated.</p>
<p><strong>edit</strong>
My data is the number of posts on an online community, a fe... | g62122 | [
0.032776929438114166,
0.018015556037425995,
0.0031531972344964743,
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0.008414013311266899,
0.03182084485888481... |
<p>It is mentioned in <a href="http://en.wikipedia.org/wiki/Determining_the_number_of_clusters_in_a_data_set#The_Elbow_Method">wiki page</a> that one of the method to determine the optimal number of cluster in the dataset is "elbow method". Here the percentage of variance is calculated as the ratio of the between-group... | g10031 | [
0.014414270408451557,
0.004293215926736593,
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0.01588859222829342,
0.01956968754529953,
0.030725236982107162,
-0.014... |
<p>The <a href="http://stackoverflow.com/questions/2691928/calculating-percentiles-in-excel-with-buckets-data-instead-of-the-data-list-it">question</a> below was asked on a sister site (Stack Overflow) back in 2010 by a user still active there (to me it seems more suitable here, for example quite similar to <a href="ht... | g19061 | [
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0.014488235116004944,
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0.017528235912322998,
0.013315096497535706,
0.06727772206068039,
-0.035... |
<p>I have implemented some internal clustering validity indexes in Java:</p>
<ol>
<li>Simplified Silhouette. </li>
<li>Calinski-Harabasz (VRC).</li>
<li>Davies -Bouldin. </li>
<li>Dunn's Index.</li>
</ol>
<p>How could I verify if my implementation is correct?</p>
<p>I have tested the indexes on Iris, Wine, Ionospher... | g62123 | [
-0.016193468123674393,
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0.008068549446761608,
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0.012138229794800282,
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0.005530006252229214,
0.002545795403420925,
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0.02740851230919361,
0.039092302322387695,
0.04566536098718643,
0.039853014051914215,
-0... |
<p>I have univariate time series data (windspeed at a particular place) measured at 1 hour interval for 5 years. </p>
<p>I used <code>auto.arima()</code> to get the following parameters:</p>
<pre><code> ar1 ar2 ma1 ma2 intercept
1.5314 -0.55 -0.1261 0.032 10.1223
... | g62124 | [
-0.001962847076356411,
-0.11203120648860931,
0.014429237693548203,
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0.020972970873117447,
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0.07910316437482834,
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0.0030366673599928617,
-0.0013371348613873124,
0.08205429464578629,
0.0669345110654831,
-0... |
<p>A ARMA(p,q) process is weakly stationary, iff the root of its AR part is not on the unit circle. So its weak stationarity doesn't depend on its MA part.
But what can the positions of the roots of its MA part imply?</p>
<p>In the unit root tests for ARIMA, a unit root of the MA polynomial indicates that the data wer... | g19063 | [
0.07870742678642273,
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0.020711328834295273,
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0.030639106407761574,
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-0... |
<p>I am trying to get the raw value of AIC that I can see as a result of the summary function.</p>
<pre><code>x = forecast(ets(ts(data, start=2000, frequency=12)),h=6)
summary(x)
</code></pre>
<p>This shows me an AIC value:</p>
<pre><code>AIC AICc BIC
7.995437 27.995437 7.779078
</code></pre>
<p>When... | g62125 | [
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0.015804044902324677,
0.04501611366868019,
0.12380186468362808,
0.0096... |
<p>I am running a GEE on <code>SPSS</code> as well as <code>Stata</code> on choice data with the following structure:</p>
<p>Each subject completed 32 trials in 4 blocks, 8 trials per block, on which he/she chose between two options. The four blocks represent two within-subjects factors crossed with each other. Subjec... | g62126 | [
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0.04428795352578163,
0.017672035843133926,
0.046174533665180206,
... |
<p>Suppose you have a classifier $C^n$ which continuously outputs a stream of classification labels $K^n_i$ and corresponding timestamps $T^n_i$. Also, we know the prior probability $P(K^n) \forall n$. Now, suppose we have several classifiers obtaining classification labels from different sources of data but all attemp... | g62127 | [
0.007276287768036127,
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0... |
<p>I've run a simulation study in order to determine type I error rate of a statistic.My simulation design includes threes factors as sample size (4 levels), test length or number of items (3 levels) and estimator (3 levels). The statistic is developed to measure person fit with test data in educational testing situati... | g19066 | [
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0.018818363547325134,
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0.04... |
<p>I've done 2-sample test for equality of proportions with continuity correction. (This is the second course of statistic I'm studying so I know basically nothing, at least so it feels.)</p>
<p>I'm using <code>R</code> and Rstudio for the first time in this course. I have no idea how to interpret the results of this ... | g62128 | [
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0.011548724956810474,
0.019516201689839363,
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0.0... |
<p>I think that dynamic pricing algorithms (used in aviation and ticketing industry) is very statistical based, anyone here has experience with those algorithms with references for it?</p> | g49127 | [
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<p>If $X = \{ x_1,\cdots x_n\}$ is a set of feature vectors, then the k-means algorithm tries to minimize the objective function $O = \sum_{i=1}^{k}\sum_{x \in G_i}||x -\mu_i ||^2$ in order to cluster $n$ feature vectors into $k$ clusters, namely $G_1 \cdots G_k$. Here $\mu_i$ is the centroid of cluster $G_i$. </p>
<... | g62129 | [
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<p>I work on quite a lot of statistical modelling, such as Hidden Markov Models and Gaussian Mixture Models. I see that training good models in each of these cases requires a large (> 20000 sentences for HMMs) amount of data that is taken from similar environments as the final use. My question is: </p>
<ol>
<li>Is th... | g49128 | [
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<p>I'm in a little debate with a colleague about hypothesis testing and interpretation. Your insights, link, or edits to get us on track are really appreciated! I won't tell you which side of the debate I'm on, but here is the situation:</p>
<p><em><strong>Situation 1</em></strong></p>
<p>Subjects are divided into ... | g62130 | [
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<p>I am looking at setting up an experiment concerning a hobby of mine, basically measuring a variety of parameters 'before' and 'after' and see which one, if any, gives the most reliable prediction of a final parameter i.e. do they have a linear relationship, etc. The object being to save some time and effort later <... | g37587 | [
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<p>I want to sample according to a density
$$
f(a) \propto \frac{c^a d^{a-1}}{\Gamma(a)} 1_{(1,\infty)}(a)
$$
where $c$ and $d$ are strictly positive.
(Motivation: This could be useful for Gibbs sampling when the shape parameter of a Gamma density has a uniform prior.)</p>
<p>Does anyone know how to sample from this... | g62131 | [
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0.017832446843385696,
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... |
<p>Given $p$-variate normal $X \sim \mathcal{N}\left(\mu,\Sigma\right)$, consider the random variable
$$
t_* = \frac{X_1}{\sqrt{\sum_{2\le i \le p} X_i^2}}.
$$
For some values of $\Sigma$, this generalizes the doubly noncentral t-distribution (which generalizes the singly noncentral t-, which generalizes the central t-... | g19072 | [
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<p>Likelihood methods have many desired properties. Sadly, local maxima in finite samples is not one of them. The fact a local maximum exists near the true parameter value is of no comfort if one converges to different local maxima. </p>
<p>I am looking for works reviewing this problem, demonstrating it, and offering ... | g22332 | [
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<p>What should be the ratio of number of observations and number of variables?
How to detect overfitting in the neural network model and what are the ways to avoid overfitting?
If I want to perform classification with Neural Network, should the classes have equal frequency?
Please help me out.</p> | g19073 | [
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0.004785508848726749,
0... |
<p>When asked to "find all frequent Item sets" is it just the set that was last worked out that is the answer you should give or is it necessary to give all before that too.</p>
<p>For example, say if the last results I get for a set is (A,B,D) then is that my frequent item set or do I need to also include all found ... | g62132 | [
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... |
<p>While working on a big data set made of 10-minutes-points of information - i.e. <code>144</code> points per day, <code>1008</code> per week and <code>52560</code> per year - I encountered a few problem in R. The information concerns electricity load on a source substation during the year.</p>
<h3>Multiple seasonali... | g1246 | [
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0.0022... |
<p>Having the <code>sensitivity</code> and <code>specificity</code> values, what software do you recommend that enables drawing the <code>ROC</code> curve provided this data?</p>
<p>Thanks.</p> | g19075 | [
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0.... |
<p>In summary: given confusion matrices (TP/TN/FP/FN) from 8 runs on real data and x runs on simulated data, show that the results from simulated data behaves similar to that of the real data.</p>
<p>More detail:
I'm working on project of sorting/classifying mineral ores for my research (in Computer Science). I take d... | g62133 | [
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0.0033499791752547026,
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0.05610272288322449,
0.04415234923362732,
... |
<p>We have a last assignment for my poli sci stat class and these two have really got me stumped. We really didn't go over multiple regression very well so if anybody can help, I appreciate it! </p>
<ol>
<li><p>Your dependent variable is “Child Deaths,” and your independent variables include a dummy variable called ... | g27676 | [
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0.023273000493645668,
0.013745795004069805,
... |
<p>My neurology experiment has a spike detector outputting <code>40</code> sample long spike waveforms.</p>
<p>I'm using a dictionary method for sorting the spikes in real time. To obtain the dictionary at start of program, I want to use all the spikes detected in the first <code>30</code> seconds and perform an <code... | g36655 | [
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0.0016726722242310643,
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0.05437399446964264,
0.030048850923776627,
0.0... |
<p>I'm using Bernhard Pfaff's packages {urca} and {vars} to analyze 3 time series. Each is I(1) and cointegrated with $r =2$ cointegrating relationships.</p>
<p>The <em>vec2var</em>() command should make the conversion from the <strong>ca.jo</strong> object (my VECM) to its VAR representation in levels. But I do not... | g19080 | [
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0.06854207813739777,
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/28936/how-to-compute-significant-interaction-estimates-when-main-effect-is-not-signifi">How to compute significant interaction estimates when main effect is not significant?</a> </p>
</blockquote>
<p>I am ... | g49635 | [
-0.011455929838120937,
-0.009040608070790768,
0.010253066197037697,
-0.0335032157599926,
0.023400267586112022,
0.0269020963460207,
0.06223065033555031,
0.033248163759708405,
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0.007696669083088636,
0.00561159010976553,
0.0022970768623054028,
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0.04... |
<p>I am in Psychology and trying to explore the utility of mixed modeling for analyzing my repeated-measures data in a factorial experiment. The primary reason for using mixed models is that I would like to avoid the common practice of averaging data collected in the same experimental condition. My understanding is tha... | g62134 | [
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0.008231090381741524,
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0.03557518869638443,
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-0.01618320494890213,
0.007243262138217688,
-0.02034091204404831,
0.0015400928677991033,
... |
<p>I am estimating a hurdle model, which consists of two data-generating processes: one for the zero/positive relationship, and a different one for the positive numbers above zero. A binary logit model is often used for the first part, and a zero-truncated poisson or negative binomial model for the second.</p>
<p>In R... | g49136 | [
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0.009781362488865852,
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0.019626213237643242,
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0.030166147276759148,
0.023076368495821953,
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-0.02425464428961277,
-0.040343333035707474,
0.04171431064605713,
0.001440119929611683,
... |
<p>Are there any good reasons to prefer a sliding model training window to a growing window in online time series forecasting (or vice versa)? I'm particularly referring to financial time series.</p>
<p>I would intuitively think a sliding window should perform worse -- out of sample-- as it is has more potential for ... | g989 | [
0.02680768072605133,
0.033487945795059204,
0.020597372204065323,
0.0031104572117328644,
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0.06874525547027588,
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0.00751468213275075,
0.03374627232551575,
0.028939304873347282,
0.043272558599710464,
0.05... |
<p>I have a time series of proportions, $x_t = \frac{a_t}{b_t}$ i.e.</p>
<p>$x_1 = 2 / 30, x_2 = 1/10$, ...</p>
<p>I want to smooth $x_t$. Should I apply a smoothing function directly to $x_t$, or should I smooth $a_t$ and $b_t$ individually, then recompute the proportions? </p>
<p>My gut tells me you should smoot... | g62135 | [
0.04126916080713272,
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0.016546009108424187,
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0.028684061020612717,
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0.0437040850520134,
0.05761461704969406,
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0.03891724720597267,
0.017320984974503517,
0.02241929993033409,
0.04905562102794647,
0.0254914... |
<p>We are preparing one event for our customers and I need to count numbers we need to prepare for this event (I think my question belongs to statistics and it isn't a homework).</p>
<p>Inputs:</p>
<ul>
<li>We have 26 ASCII letters (ASCII codes 65-90) from which customers choose. When somebody choose a letter, he doe... | g62136 | [
-0.03476967290043831,
0.07695005089044571,
0.010339001193642616,
-0.08363349735736847,
0.01947169378399849,
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0.019215591251850128,
0.04095382243394852,
0.003890541847795248,
-0.061051953583955765,
0.03405938670039177,
0.04456976428627968,
-0.00731... |
<p>How would you go about explaining i.i.d to non techncial people?</p> | g37870 | [
0.010844976641237736,
0.0609416589140892,
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0.01670672930777073,
0.06169092282652855,
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0.013743245974183083,
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0.0062355464324355125,
-0.0006285631679929793,
0.006694894749671221,
0.... |
<blockquote>
<p>A certain town has two taxi companies, the Green Taxi Co (cars coloured green) and the Blue
Taxi Co (cars coloured blue). 10% of taxis are the Green and 90% are the Blue. There was an
accident on a dark evening, and the witness claimed a Green cab was involved. On future testing, they discovered t... | g39005 | [
0.036059606820344925,
-0.008046858943998814,
0.02492624707520008,
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-0.02746208757162094,
0.019029652699828148,
0.028360843658447266,
0.027987204492092133,
... |
<p>Say there are two variables. Variable A has a higher $\beta$ weight than variable B but variable B has a higher t-statistic than variable A. Can either of these measurements, standardized $\beta$ or t-value, offer better predictive power over the other? Must t-value and $\beta$ be taken into consideration together ... | g19089 | [
0.02536592073738575,
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-0.010668233968317509,
-0.01187626551836729,
0.027768151834607124,
0.002403984311968088,
... |
<p>I am trying to do a correlation between a 4 level likert scale with 11 items and a dichotomous present-not present scale of the same 11 items. Can I do this?</p> | g62137 | [
0.014045929536223412,
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0.006579509936273098,
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0.047916628420352936,
0.... |
<p><strong>Question</strong></p>
<p>Consider the following transition matrix:</p>
<pre><code> P=
0 0 1 0 0 0
0 0 0 0 0 1
0 0 0 0 1 0
1/4 1/4 0 1/2 0 0
1 0 0 0 0 0
0 1/3 0 0 0 2/3
</code></pre>
<p><s... | g48387 | [
-0.0018965133931487799,
-0.011216633953154087,
0.014148661866784096,
-0.030474558472633362,
0.06587743759155273,
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0.04144199192523956,
0.017096592113375664,
-0.008120330050587654,
0.019772980362176895,
-0.08874138444662094,
0.0614539198577404,
-0.020964575931429863,
0... |
<p>there are several distinct usages:</p>
<p>kernel density estimation<br>
kernel trick<br>
kernel smoothing</p>
<p>Please explain what the "kernel" in them means, in plain English, in your own words</p> | g49145 | [
0.04308624565601349,
0.04448602348566055,
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0.0253206305205822,
0.05131160467863083,
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0.02198711968958378,
-0.004724049940705299,
-0.009799218736588955,
0.04341161996126175,
0.0619337... |
<p>From <a href="https://en.wikipedia.org/wiki/Kruskal%E2%80%93Wallis_test#Exact_probability_tables" rel="nofollow">Wikipedia</a></p>
<blockquote>
<p>A large amount of computing resources is required to compute <strong>exact probabilities</strong> for the Kruskal-Wallis test. Existing software only provides <strong>... | g62138 | [
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<p><a href="http://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence">Kullback-Leibler divergence</a> is a metric to compare two probability density functions, but what metric is used to compare two GP's $X$ and $Y$?</p> | g36730 | [
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<p>I would like to use <code>lme4</code> to fit a mixed effects regression and <code>multcomp</code> to compute the pairwise comparisons. I have a complex data set with multiple continuous and categorical predictors, but my question can be demonstrated using the built-in <code>ChickWeight</code> data set as an example:... | g62139 | [
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... |
<p>I'm concerned to seasonal adjustment procedure and want to know the criteria for this purpose can anyone please give me the answer of the following question.
what should be the criteria for seasonal adjustment whether to do or not to do?</p> | g62140 | [
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0.... |
<p>I have some environmental data I am examining (samples from water of a lake).</p>
<p>After next generation sequencing and some computation I get some OTUs (Operational Taxonomic Units) saying which bacteria are in which environmental samples (150 samples).</p>
<p>First I filtered for the OTUs which have a high abu... | g62141 | [
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<p>I would greatly appreciate any of you who could help me with this challenge. I am going to state the problem in sequential order, so as to make it clear:</p>
<ol>
<li><p>I have $n$ normally distributed random variables.</p></li>
<li><p>I have statistical data for each random variable (thus, their mean and variance)... | g48414 | [
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<p>I'm looking for the appropriate theoretical framework or speciality to help me deal with understanding how to deal with the errors that the GPS system has - especially when dealing with routes.</p>
<p>Fundamentally, I'm looking for the requirements on the data and any algorithms to use to be able to establish the l... | g49751 | [
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<p>A former colleague once argued to me as follows: </p>
<blockquote>
<p>"we usually apply normality tests to the results of processes that,
under the null, generate random variables that are only
<em>asymptotically</em> or <em>nearly</em> normal (with the 'asymptotically' part dependent on some quantity which w... | g49510 | [
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