question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I'm using <a href="http://www.r-project.org/" rel="nofollow"><strong>R</strong></a> and the manuals on the R site are really informative. However, I'd like to see some more examples and implementations with R which can help me develop my knowledge faster. Any suggestions?</p> | g49454 | [
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<p>Given that a power series distribution is a distribution that can be expressed as</p>
<p>$$f_{\theta}(x) = {{a\theta^x}\over{C(\theta)}}$$</p>
<p>where $a$ is a sequence of non-negative real numbers, I've also seen it expressed as $a(x)$. I understand that you can re-parametrize a function so that there are separa... | g67799 | [
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<p><strong>Duplicate thread:</strong> <a href="http://stats.stackexchange.com/questions/1676/i-just-installed-the-latest-version-of-r-what-packages-should-i-obtain">I just installed the latest version of R. What packages should I obtain?</a></p>
<p>What are the <a href="http://www.r-project.org/">R</a> packages you co... | g27493 | [
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<p>Commonly, <strong>normalization</strong> of ratings seems to mean adjusting values measured on different scales to a notionally <strong>common scale</strong>.</p>
<p>I have different metrics that measure different <strong>performance aspects</strong> of a server. I want to <strong>aggregate these values</strong>. T... | g67800 | [
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<p>Suppose that one has data on a proportion $P$ measured on a continuous scale. Further suppose that this data has a grouped structure -- some proportions are clustered according to a certain variable $g$ (location, say). Further say that you've got a covariate $X$ that your think is correlated with $P$. You want t... | g67801 | [
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<p>I am using a generalized formula for normalizing one data range to another but am having difficulty finding its formal name, if it even exists (sorry if my notation is strange):</p>
<p>$$
x_b = min_b + \frac{(x_a - min_a)(max_b-min_b)}{max_a - min_a}
$$</p>
<p>This converts an $x$ in range $a$ to its respective va... | g5380 | [
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<p>I am specifying a latent growth curve model in MPLUS with a time-invariant predictor of the growh curve. </p>
<p>The time-invariant predictor is a team diversity measure (standard deviation) which is based on a 7 item survey scale. Each team has 5 team members. </p>
<p>My question is whether the correct approach w... | g67802 | [
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<p>Let's say I have a set of data which are lognormal-distributed and I want to
create boxplots. The part of the values which is symbolized by the <em>box</em> may lie somewhere around 1. In that case, the inter quartile range will also be single digit. With the lower values lying somewhere below 0.1, even the most ext... | g67803 | [
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<p>First of all, I would just like to point out I have next to nothing knowledge about data representation, so I would be more then thankful if someone could answer this question on as basic level as it could be.</p>
<p>I have three different data sets which I need to plot on the very same graph. The first data set is... | g48193 | [
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<p>I would like to find if there is a significant difference between two ROC-curves. I've found the roc.test in the pROC package. However, I cannot seem to find any information on how this test is actually performed. Can anyone explain it to me or refer to a webpage that has information on this?</p>
<p>From the <a hre... | g67804 | [
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<p>I am not very familiar with filters. The Hodrick-Prescott filter as one can find it e.g. <a href="http://en.wikipedia.org/wiki/Hodrick%E2%80%93Prescott_filter" rel="nofollow">in wikipedia</a> is two-sided. I also found an R implementation for this in the R package <a href="http://cran.r-project.org/web/packages/mFil... | g43205 | [
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<p>If I have a sample $(X_i,Y_i)_{i=1}^n$ I can estimate the joint CDF by:
$$F_{X,Y}(x,y) = \frac{1}{n}\sum_{i=1}^nI[X_i\leq x,Y_i \leq y]$$
Assume now I observe only $(X_i)_{i=1}^n$, but I know that $Y\sim U[0,1]$. How does one estimate the bivariate CDF in this case? I would be thankfull for any reference or suggesti... | g43250 | [
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<p>I've read about two ways to test the significance of just one predictor when fitting a linear model with least squares. </p>
<p>Suppose I fit the following linear model using least squares using standard assumptions.
$$y = X \beta + \varepsilon \tag{1}$$
where $\beta = (\beta_1, \cdots, \beta_i, \cdots, \beta_p)^T$... | g67805 | [
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<p>I have a learning to rank system where implicit feedback (from user clicks) is used to determine +ve and -ve examples for the training. The problem is that (obviously) the learner sees only the top few ranked results (+ve or more relevant examples will appear at the beginning). This introduces some kind of a bias in... | g67806 | [
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<p>I have a time series monitoring data set that looks like below:
The response is a count.</p>
<pre><code> Site Year Response Effort
1 1 1 8 3
2 1 2 NA 0
3 1 3 9 3
4 1 4 7 2
5 2 1 4 2
6 2 2 NA 0
7 2 ... | g27501 | [
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<p>The problem is how to estimate, by sampling, the mean of a very right asymmetrical distribution (even with right outliers)</p> | g67807 | [
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<p>I'm defining a Multinomial-Dirichlet model in JAGS and want to assign some hyperpriors to the parameters of the Dirichlet distribution. In the WinBugs manual I read that "the parameters of Dirichlet and Wishart distributions and the order (N) of the multinomial distribution must be specified and cannot be given prio... | g27502 | [
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<p>I have a dataset of three groups of cells treated with 10 different compounds and am not sure how to check for significant differences between those treatments. Within each group the data is also paired. </p>
<p>I tried doing an two-way ANOVA; however, that doesn't work because of the unbalanced sample size. I then... | g67808 | [
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<p>Although the title of the question appears trivial, I would like to explain that it is not that trivial in the sense that it's different from the question of applying the same statistical test in similar datasets to test against a total null hypothesis (meta-analysis, e.g. using Fisher's method for combining p-value... | g67809 | [
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<p>I am running a summary(aov(…)) in R and I got this message:</p>
<p><code>Estimated effects may be unbalanced</code></p>
<p>What does it mean? How may I solve this problem?</p> | g27503 | [
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<ol>
<li><p>The "classical" MAP estimation: $$\hat\theta = \arg\max_{\theta}P(\theta|\mathbf{x})$$ where $\mathbf{x}$ are the observations and $\theta$ are the parameters. </p></li>
<li><p>In this <a href="http://mitpress.mit.edu/sites/default/files/titles/content/9780262015776_sch_0001.pdf" rel="nofollow">book chapter... | g67810 | [
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<p>I tried fitting an ARMA(1,1)/GARCH(1,1) model to my data consisting of around 5000 data points but I got significant results in Ljung Box test on standardized residuals and squared residuals. However when I used only the last 3000 data points the model showed much better results with non-significant standardized res... | g67811 | [
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<p>I want to classify images as "normal" or "lesions", and then rate the images in the lesions category from mild and severe.
This classification would be based on edge, color and texture features.
For this concept I want to use a binary SVM classifier using threefold cross validation, in Matlab.
Where do I start?</p> | g48198 | [
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<p>When using the <code>step.plr()</code> function in the <a href="http://cran.r-project.org/web/packages/stepPlr/index.html" rel="nofollow">stepPlr</a> package, if my predictors are factors, do I need to encode my predictors as dummy variables manually before passing it to the function? I do know that I can specify "l... | g67812 | [
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<p>Can you explain what is a <a href="http://www.originlab.com/www/helponline/origin/en/UserGuide/Fit_Exponential.html#Second_order_exponential_decay_.28Exponential_Decay.2C_2_term.26ldots.3B.29" rel="nofollow">second order exponential decay function</a>:
$$
y(x) = y_0+A_{1}e^{-\frac{x}{t_1}}+A_{2}e^{-\frac{x}{t_2}}
$$... | g67813 | [
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<p>I'm currently on a project where I basically need, like we all do, to understand how output $y$ is related to input $x$. The particularity here is that data $(y,x)$ is given to me one piece at a time, so I want to update my analysis every time I receive a new $(y,x)$. I believe this is called "on-line" processing, a... | g27508 | [
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<p>Does it matter how many levels the independent variable has for significance? For example, suppose socioeconomic status has 10 levels and the output variable has 2 levels. Suppose this is significant in a $\chi^2$ test. If we increase the number of levels to 20 for the independent variable would this change the sign... | g48205 | [
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<p>In four different experiments, I ran two programs <code>A</code> and <code>B</code> with different parameter setteings <code>a</code>, <code>b</code>, and <code>c</code>. Target variable is kind of time -- lower Target value means higher performance. I know the reasons why program <code>A</code> is better than <code... | g67814 | [
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<p>Let's say as a business owner (or marketing or anyone who understands a scatter plot) is shown a scatter plot of two variables: number of advertisements vs number of product sales per month for the past 5 years (or another time-scale so that you have more samples. I just made this one up).</p>
<p>Now he/she see's t... | g14075 | [
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<p>I have three variables, x,y, z. My sample n is about 17,000.</p>
<p>My pearson coeficients & r^2:</p>
<p>for x -> z it is 0.187, 0.034</p>
<p>for y -> z it's 0.311, 0.096</p>
<p>testing for significance, I receive a z-score of 12.3 & p < 0.00</p>
<p>So, I know the difference is significant, but I wan... | g14079 | [
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<p>In baseball, Bill James suggested using, to predict next season's winning percentage
<code>runs_scored^2/(runs_scored^2 + runs_allowed^2)</code>, rather than this season's winning percentage, because there is a great deal of luck involved in winning games. Similarly, I think the number of points a football (America... | g48207 | [
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0.047243695706129074,
0.053536467254161835,
0.08727127313613892,
-0.03... |
<p>I am beginner to data mining.
This is my understanding, regression is used to predict continuous values. It is a type of classification.
Classification is Supervised and Clustering is unsupervised.
In classification we have predefined classes, whereas in clustering there are no classes defined.
What does this exactl... | g67815 | [
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0.043686166405677795,
0.06521628051996231,
0.0124... |
<p>I have a dataset which only has one continuous variable, and I try to use decision tree algorithm to build a model which classify the +ve and -ve label from the dataset. I run 10-fold cross-validation.</p>
<p>How is the AUC calculated for the decision tree classifier? Will the algorithm check different threshold va... | g67816 | [
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<p>I am working in Program R. I am conducting analysis on zero inflated over dispersed data. I am leaning towards hurdle regression with the count aspect modeled in a negative binomial framework. I am interested in assessing the model fit and stumbled upon this <a href="http://www.plosone.org/article/info%3adoi/10.1371... | g67817 | [
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<p>If you are running K-medians, and your distance metric is the L1 norm, how do you derive that the center of each centroid is the median of the data points assigned to it?</p>
<p>Second, how do you compute the geometric median?</p>
<p>Third, are there any implementations of k-medians algorithm?</p> | g14089 | [
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<p>I've got a question.</p>
<p>Let's say I have a medical data representing 2 classes of patients (healthy and unhealthy) and some number of predictors which characterize these patients. Choosing different combinations of predictors I may construct logistic regression model (for distinguishing healthy and unhealthy pa... | g67818 | [
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0.023179614916443825,
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<p>I have an exam in two days and can't figure this out at all:</p>
<blockquote>
<p>In the local cola canning factory, the mean fill of cans is set at 300
milliliters but there is concern that the population mean fill may not
in fact be 300ml. Assume that the standard deviation of the amount
of cola in a rando... | g67819 | [
0.027926549315452576,
0.031042203307151794,
0.015677746385335922,
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0.0017749319085851312,
0.0028555961325764656,
0.024736398831009865,
0.013010108843445778,
0.016970409080386162,
... |
<p>Let $U \subset \mathbb{R}^n$ be a vector space with $\dim(U)=d$. A standard normal distribution on $U$ is the law of a random vector $X=(X_1, \ldots, X_n)$ taking values in $U$ and such that the coordinates of $X$ in one ($\iff$ in any) orthonormal basis of $U$ is a random vector made of $d$ independent standard nor... | g48208 | [
0.047756489366292953,
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-0.014705140143632889,
0.006830327678471804,
0.00014029277372173965,
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... |
<p>Under what circumstances will the Kalman filter implementation in proc UCM fail?</p>
<p>High variance of the constituents is one case. Are there other cases you've encountered?</p>
<p>Anything other than :<a href="http://support.sas.com/documentation/cdl/en/etsug/63939/HTML/default/viewer.htm#etsug_ucm_sect031.htm... | g27519 | [
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<p>In R I created a gradient boosted random forest from 100,000 records with 10 cross validation folds using the <code>gbm</code> library. I want to communicate the strength and accuracy of the model, because it worked very well (far surpassing the random forest, kNN or SVM).</p>
<p>There are plenty of strength and ac... | g67820 | [
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0.02565605565905571,
0.004... |
<p>I'm not too great at statistics, so apologies if this is a simplistic question. I am fitting a curve to some data, and sometimes my data best fits a negative exponential in the form $a * e^{(-b * x)} + c$, and sometimes the fit is closer to $a * e^{(-b * x^2)} + c$. However, sometimes both of those fail, and I would... | g67821 | [
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0.026989195495843887,
0.025489049032330513,
0.02432434819638729,
-... |
<p>I want to visualize the results of a clustering (produced with <code>protoclust{protoclust}</code>) by creating scater plots for each pair of variables used for classifying my data, colouring by classes and overlapping the ellipses for the 95% confidence interval for each of the classes (to inspect which elipses-cla... | g67822 | [
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0.03607688844203949,
0.03593853861093521,
0.057157088071107864,
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<p>I have a multiple regression problem, which I tried to solve using simple multiple regression:</p>
<pre><code>model1 <- lm(Y ~ X1 + X2 + X3 + X4 + X5, data=data)
</code></pre>
<p>This seems to be explaining the 85% of variance (according to R-squared) which seems pretty good.</p>
<p>However what worries me is ... | g49670 | [
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0.054912302643060684,
0.005775132682174444,
0.01... |
<p><em><strong>TL, DR summary:</em></strong></p>
<p>Is there any theoretical or empirical basis to support the following statement being true as a general rule of thumb?</p>
<p>"When estimating a mixed model, typically the estimated variances/standard deviations of random effects associated with 'higher-order' terms ... | g143 | [
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0.008878975175321102,
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0.04430048540234566,
0.022... |
<p>A penalized regression provides biased estimates of the regression coefficients (bias-variance trade-off principle). Therefore, standard errors and confidence intervals are regarded as not very meaningful for those biased estimates arising from (frequentist) penalized regression method, see e.g. the discussion <a h... | g67823 | [
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0.0009433999075554311,
0.011458626948297024,
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0.03027927130460739,
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<p>I have two different analytical methods that can measure the concentration of a particular molecule in a matrix (for instance measure the amount of salt in water)</p>
<p>The two methods are different, and each has it's own error. What ways exist to show the two methods are equivalent (or not).</p>
<p>I'm thinking... | g27523 | [
0.03379225730895996,
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0.02320987917482853,
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0.008283976465463638,
0.04545429348945618,
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0.05555914714932442,
0.0612... |
<p>I am trying to model a system that generates events modeled by a Poisson process.</p>
<p>I am using the following ruby code:</p>
<pre><code>INTERVAL = 0.005
LAMBDA = 167.0
events = Hash.new(0)
def f(x, lambda)
1 - Math.exp(-lambda * x)
end
random_gen = Random.new
start = Time.now.to_f
while Time.now.to_i - st... | g67824 | [
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0.0008247598889283836,
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0.01951010152697563,
... |
<p>I am testing for cointegration all the pairs from a set of 100 stocks. I run an Ordinary Least Square Regression on each pair and then I test for the existence of unit roots in the residuals. I am using the ADF test with no trend and no intercept.
I am surprised that I found a big amount of pairs which the test on ... | g48223 | [
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0.04413994774222374,
0.001134089077822864,
-0.0... |
<p>I am examining the relationship between a categorical variable and a quantitative one. For the test of linearity, I was told that I must use scatter plots. However, this is no longer applicable if one of the variables is categorical. So I resorted to box plots. Now, I have difficulty identifying/checking if there is... | g67825 | [
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0.007240959908813238,
0.03847084194421768,
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0.0... |
<p>I have to forecast a large set of (hierarchical) time series and since the R package <a href="http://cran.r-project.org/web/packages/hts/index.html" rel="nofollow">hts</a> allows for confidence intervals for their ensemble, I'd like to use it. I haven't found an example of how to use it, yet. How should I forecast t... | g67826 | [
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<p>I have a several hundreds of measurements. Now I am considering utilizing some kind of software to correlate every measure with every measure. This means that there are hundreds of correlations. Among these there should (statistically) be a high correlation, even if the data is completely random (each measure has on... | g67827 | [
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0.009098902344703674,
0.05653... |
<p>In a double-blind study, when are deviations from the control group considered statistically significant? And is this related to the number of samples?</p>
<p>I realise that every experiment is different and statistical significance should depend on the deviations in measurements and the size of the sample group, b... | g27527 | [
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0.023904699832201004,
0.11099060624837875,
... |
<p>Consider translated <a href="http://en.wikipedia.org/wiki/Weibull_distribution" rel="nofollow">Weibull distribution</a> with probability density function:</p>
<p>$$
f(x ; k, \lambda, \theta) = \frac{k}{\lambda} \left( \frac{x-\theta}{\lambda} \right)^{k-1} \exp\left( - \left(\frac{x-\theta}{\lambda} \right)^k \r... | g49651 | [
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0.030909651890397072,
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0.02567681483924389,
0.... |
<p>So I originally thought I would be able to solve this problem fairly easily with ANCOVA, but now that I've thought more deeply about it I realized it is not so simple.</p>
<p>Essentially we have a scalar response variable, $y$ which we want to predict using three variables $x$, $c$ and $g$. $x$ is a scalar variable... | g27537 | [
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0.011846333742141724,
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0.0325486920773983,
-0.0021447609178721905,
-0.001223766477778554,
0.03432082012295723,
0.00... |
<p>I want to plot $15$ random draws of Dirichlet distribution with $\alpha = 1$ and dimension $n=10$ in R. </p>
<pre><code>require(MCMCpack)
alpha <- 1
draws <- 15
dimen <- 10
x <- rdirichlet(draws, rep(alpha, dimen))
</code></pre>
<p>I want an output similar to the following image. This image is from ... | g67828 | [
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0.04416327923536301,
0.01... |
<p>I have used LDA on a corpus of documents and found some topics. The output of my code is two matrices containing probabilities; one doc-topic probabilities and the other word-topic probabilities. But I actually don't know how to use these results to predict the topic of a new document. I am using Gibbs sampling. Doe... | g43139 | [
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0.030883602797985077,
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0.014564232900738716,
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0.024383261799812317,
-0.0015170115511864424,
0.0543525256216526,
... |
<p>I am running a relatively simple propagation of error analysis on an equation:</p>
<p>$$S = \frac{ABC}{XY}$$</p>
<p>I have independent random error terms calculated for each variable (for the purposes of this analysis I am assuming systematic errors to be negligible), but I am having a specific issue with the $C$ ... | g27541 | [
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0.04540427029132843,
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0.0011243221815675497,
-0.010637838393449783,
0.032812125980854034,
0.0007541421218775213,
0... |
<p>I am having somewhat of a problem setting up contrasts from an anova in R. I have done this in the past, but at the moment I don't seem to be able to get R to use my contrast matrix instead of the treatment contrasts. Any help on this would be greatly appreciated, I guess its possible I am making some basic mistake ... | g27542 | [
0.005699455738067627,
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0.04424329847097397,
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0.10775552690029144,
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... |
<p>Say I have 3 random variables ${X, Y, Z}$, and I have collected an iid sample of size $N$ from them: ${\cal D} = \{ (x_i, y_i, z_i), i = 1,\dots,N \}$.
The conditional expectation $E[ X | y ]$ can also be written as </p>
<p>\begin{eqnarray*}
E[ X | y ] = \int E[ X | y, z ] \,\, dF_{ Z | Y }(z)
\end{eqnarray*}</p>
... | g27545 | [
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0.02045678161084652,
0.03283640369772911,
0.03739495202898979,
0.04... |
<p>Let $X \in \{0,1\}^{n \times m}$ be a matrix with $n,m \geq 600$.</p>
<p>I want to calculate the correlations between the columns of the matrix $X$. To be more precise, I need the correlation matrix $C \in [-1,1]^{m \times m}$.</p>
<p>My question is, is a rank correlation coefficient like Spearman's $\rho$ or Kend... | g27546 | [
0.014021485112607479,
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0.058901481330394745,
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0.048187099397182465,
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0.027739116922020912,
-0.03470328822731972,
0.03059368208050728,
-0.028701206669211388,
... |
<p>I have to analyse data that look at the relevance of some posts. Basically each post is rated by 100 persons, and the scale looks something like this (like a Likert scale):</p>
<ol>
<li>Irrelevant</li>
<li>Slightly relevant</li>
<li>Relevant</li>
<li>Useful</li>
<li>Extremely Useful</li>
</ol>
<p>But each person c... | g67829 | [
0.030585361644625664,
0.014458751305937767,
-0.03431599214673042,
-0.0804545134305954,
0.0008281533373519778,
0.016801565885543823,
0.008436640724539757,
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0.018020546063780785,
0.02606472373008728,
0.006944757420569658,
0.057956233620643616,
0.01... |
<p>I ran an ANOVA finding for example an interaction between gender and grade than I want to know in what grades boys and girls differ, but in many cases I find (adjusted) p-values of 0 and 1. How / why is this possible? Doesn't seem right...</p>
<pre><code>as.factor(gender) 1 16 16.2 2.6... | g67830 | [
-0.008394473232328892,
-0.050913598388433456,
0.025343162938952446,
-0.03108464553952217,
0.03864389285445213,
0.022908182814717293,
0.051600273698568344,
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0.0021234434098005295,
-0.050779011100530624,
0.027156740427017212,
0.052683256566524506,
0... |
<p>I'm looking for sources of data related to Federal regulation and enforcement. Things like the following:</p>
<ul>
<li>Size of Federal regulatory agencies (number of workers)</li>
<li>Number of pages of Federal regulations [total pages that are in force; not just new ones]</li>
<li>Number of enforcement actions br... | g27549 | [
0.011166084557771683,
0.08494823426008224,
-0.013963182456791401,
-0.02909316122531891,
-0.00477330107241869,
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0.00329570472240448,
0.030277876183390617,
0.012747392989695072,
-0.018849601969122887,
-0.029495377093553543,
-0.012792717665433884,
0.020958084613084793,
-0... |
<p>I'm working in the area of natural language processing, to be specific I'm reviewing the parsers that take advantage of data-mining techniques. </p>
<p>I've read an introduction to natural language processing, specifically the <a href="http://www.ldc.upenn.edu/acl/J/J96/J96-1002.pdf" rel="nofollow">maximum entropy ... | g67831 | [
-0.023592738434672356,
-0.02846253104507923,
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0.047862615436315536,
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-0.027268191799521446,
-0.05315663293004036,
0.010914230719208717,
0.03390925005078316,
-... |
<p>I've run a Tobit regression but I'm not sure of how I should interpret the coefficients. Do you have any suggestions? Thank you very much!</p> | g37721 | [
-0.040987059473991394,
-0.0005480091786012053,
0.006342678796499968,
-0.06009168177843094,
0.04863151162862778,
-0.019020646810531616,
0.0341840498149395,
0.04696781188249588,
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-0.020296471193432808,
-0.03633047267794609,
0.06001105159521103,
0.04170113801956177,
-0.0... |
<p>Do you know any C# library or source code that can be used for ARMA / ARIMA forecasting?</p> | g38137 | [
0.05408065766096115,
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0.017595652490854263,
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0.012355595827102661,
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0.01233549602329731,
0.05586174130439758,
0.023389799520373344,
0.06860016286373138,
0.02... |
<p>I am looking at a $\chi^2$ (crosstabs) test looking at interactions between types of dyads in an animal group. My categories are Male-Male, Male-Female, and Female-Female dyads in the rows and "Were Seen to Interact" and "Were Never Seen to Interact".<br>
The matrix looks something like:</p>
<pre><code>21 7
85 ... | g67832 | [
-0.012403680011630058,
0.020240379497408867,
-0.007567334454506636,
-0.06431366503238678,
0.05308195576071739,
-0.041461531072854996,
0.068695068359375,
-0.022650789469480515,
-0.06456397473812103,
-0.010621353052556515,
-0.00685508456081152,
0.021671388298273087,
-0.004981283564120531,
0.... |
<p>I'm writing naive bayes classifier for spam detection. </p>
<p>I'd like it to recognize difference between "Paris Hilton" and "Hilton Paris", so I'm using bigrams in addition to unigrams.</p>
<p>Currently I throw both bigrams and unigrams in one bag as independent words, but obviously they're not independent.</p>
... | g67833 | [
0.0016978969797492027,
0.00014490490138996392,
0.017462056130170822,
-0.039660293608903885,
-0.012449060566723347,
-0.005501484032720327,
0.01214215811342001,
0.06256572157144547,
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-0.0034039034508168697,
0.02542930655181408,
0.023897457867860794,
0.06683323532342911,
... |
<p>I have corrected my alpha level using Šidák correction to take into account the experiment-wise error rate, as I am doing multiple correlation tests using the same data set.</p>
<p>My new alpha is 0.00056. </p>
<p>I tried using SPSS but the p threshold (alpha) seems to be either 0.01 or 0.05 and the p value of the... | g48249 | [
0.03452073410153389,
-0.04155861958861351,
0.0029233312234282494,
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0.017897283658385277,
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0.016641560941934586,
0.06563049554824829,
0.017894135788083076,
-0.013253546319901943,
0.00116608920507133,
-0.012645173817873001,
0.030643654987215996,
0.... |
<p>I conduct a simulation experiment which produces values with some random effects involved. In theory, the results should all be some fixed value $c$.</p>
<p>What is an appropriate test to check whether the distribution converges to the fixed value?</p>
<p>I saw others using a binomial test for that purpose, but it... | g14314 | [
0.03671135753393173,
0.0336625874042511,
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0.012374233454465866,
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-0.03142058104276657,
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0.020189441740512848,
-0.007711000740528107,
... |
<p>I have one independent variable with two levels: Gender (Male and Female),
and dependent variables will be composed of three test scores: Impulsivity, Assertiveness, and Social Desirability.</p>
<p>My research question is to know the difference between males and females on all three test scores.</p>
<p>I'm confuse... | g27555 | [
-0.02841191738843918,
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0.006121564656496048,
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0.013795237988233566,
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-0.022774653509259224,
0... |
<p><img src="http://i.stack.imgur.com/uGbui.jpg" alt="boxplot of claim frequency"></p>
<p>I have done a boxplot to represent my claim frequency. However make 2 and 4 have only 1 whisker. How do I interpret that?</p> | g49786 | [
-0.0067415134981274605,
0.05387753248214722,
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0.006671626586467028,
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0.03434019908308983,
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-0.06774991005659103,
0.027492864057421684,
0.025059986859560013,
0.03364376351237297,
0... |
<p>I am trying to interpret the variable weights given by fitting a linear SVM.</p>
<p>(I'm using <a href="http://scikit-learn.org/stable/" rel="nofollow">scikit-learn</a>):</p>
<pre><code>from sklearn import svm
svm = svm.SVC(kernel='linear')
svm.fit(features, labels)
svm.coef_
</code></pre>
<p>I cannot find anyt... | g49488 | [
0.0036844704300165176,
-0.01480149757117033,
-0.008792384527623653,
-0.02959245629608631,
0.029432233422994614,
0.010917089879512787,
0.014120121486485004,
0.08067042380571365,
-0.06111368164420128,
-0.0010919903870671988,
-0.01678142510354519,
-0.026006318628787994,
0.026618391275405884,
... |
<p>Imagine following example:</p>
<p>We have two pairs of points (i.e. 4 objects in some space) and two similarity measures.
According to first similarity measure, objects from first pair are more similar then objects from second pair. On the contrary, according to second similarity measure, objects from the second pa... | g67834 | [
-0.004233296494930983,
0.016036788001656532,
0.01690160483121872,
-0.020618567243218422,
0.05204613506793976,
-0.02284151129424572,
-0.05514780804514885,
-0.021589262410998344,
-0.04724228009581566,
-0.008736052550375462,
-0.0022279901895672083,
-0.0022220732644200325,
0.031728655099868774,
... |
<p>I am trying to figure out the relationship between a dichotomous independent variable sex, an ordinal three level SES independent variable predicting a dichotomous variable for legalization of pot or against. I am confused about what test to run.</p> | g48253 | [
-0.00677462387830019,
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0.007462446577847004,
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-0.047591619193553925,
-0.014867709018290043,
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0.00806656014174223,
0.02953265607357025,
-0.015411103144288063,
-0.013747512362897396,
0.012755810283124447,
0.03764983266592026,
-... |
<p>I wanted to test the effectiveness of a particular type of "talking" therapy on depression. I envisaged selecting ONE group of people and measuring their heart rate and scores on depression scale for a period of 8 weeks. So I would have 8 measurements for the heart rate (session heart beat average) and 8 measurement... | g48254 | [
0.0054088132455945015,
0.002103509847074747,
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0.0006306286086328328,
0.0005674533895216882,
0.011849171482026577,
-0.03831752389669418,
0.024625051766633987,
0.01595735177397728,
0.020980488508939743,
... |
<p>Among the literature, some line charts use mean/SE but others use mean/SD. Which is correct or better?</p> | g44165 | [
-0.013958828523755074,
-0.004590355325490236,
-0.015029652044177055,
-0.03864249214529991,
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0.006050376687198877,
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0.02730846218764782,
-0.01779838278889656,
0.06656941771507263,
-0.031118884682655334,
0.09871358424425125,
-0... |
<p>I was looking at section 6 of these <a href="http://www.hongliangjie.com/notes/plsa.pdf" rel="nofollow">notes</a> and trying to understand the derivation of the M-step at the top of page 10. I understood the derivation for the model without background, but I do not understand where the $(1-P(Z_{d,w}=\theta_B \mid d,... | g48255 | [
0.003045549849048257,
-0.005806897766888142,
-0.025217022746801376,
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0.012123044580221176,
0.0013531595468521118,
0.09254689514636993,
0.026615474373102188,
0.0023498102091252804,
-0.036949146538972855,
-0.06935367733240128,
0.006965060718357563,
0.006228241138160229,
... |
<p>There are several threads on R-sig-ME about obtaining confidence intervals for predictions using <code>lme4</code> and <code>nlme</code> in R. For example <a href="https://stat.ethz.ch/pipermail/r-sig-mixed-models/2010q1/003445.html">here</a> and <a href="https://stat.ethz.ch/pipermail/r-sig-mixed-models/2010q2/0035... | g67835 | [
0.02053709141910076,
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0.027105029672384262,
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0.02654808573424816,
0.02436799369752407,
0.03598760813474655,
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-0.04435788094997406,
0.02448880486190319,
-0.01200108788907528,
0.027028877288103104,
0.009472... |
<p>I am analyzing data relating to networks that evolve over times (more precisely, a snap shot of the network at every discrete time step). Each node of the network denotes a person who perform some action at each time step.</p>
<p>As the network evolves, communities may emerge and we run some detection algorithm to ... | g27920 | [
-0.007718116510659456,
0.012991050258278847,
-0.010906037874519825,
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0.06084735319018364,
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0.04474910721182823,
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-0.021572168916463852,
-0.05334916710853577,
-0.029867414385080338,
0.030691996216773987,
... |
<p>I have the following challenge: The dataset has one dependent and one independent variable which are connected in a non-linear fashion. I am trying to give a more qualitative picture here because I am unsure how to handle the dataset. </p>
<p>Basically there are five regions from "one end to the other":</p>
<ol>
<... | g48258 | [
-0.008970136754214764,
-0.05216703191399574,
-0.021823536604642868,
-0.052210018038749695,
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-0.038548510521650314,
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-0.049129050225019455,
-0.03499557450413704,
0.027518361806869507,
0.0029170841444283724,
0.03704172000288963,... |
<p>My task is to test if there's change in covariance matrix of 6 variables. Values of 6 variables are measured twice from same subjects (3 years between measurements). </p>
<p>How can I do that? I've been doing most of my work using SAS.</p> | g27562 | [
0.024537431076169014,
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0.02387089468538761,
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0.03254114091396332,
-0.0065068998374044895,
... |
<p>I got this question on a test:</p>
<blockquote>
<p>The average jumping distance for males between the ages of 20 to
30 is 6.5 feet with a standard deviation of 0.523 feet. What is the
probability, from a sample of 5 males between the ages of 20 to 30,
having a sample mean jumping distance between 6 and 7 fe... | g49811 | [
-0.0024902645964175463,
0.08016374707221985,
0.010232582688331604,
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-0.02977145090699196,
-0.036629561334848404,
-0.008525381796061993,
0.042207036167383194,
... |
<p>I have following type of data. I have evaluated 10 individuals each repeated 10 times. I have 10x10 relation matrix (relationship between all combination of the individuals).</p>
<pre><code>set.seed(1234)
mydata <- data.frame (gen = factor(rep(1:10, each = 10)),
repl = factor(rep(1:10, 10))... | g562 | [
0.003374670399352908,
-0.047321073710918427,
0.0004478774208109826,
-0.028332985937595367,
-0.0006925328052602708,
-0.02962898463010788,
0.05482596531510353,
0.01085069589316845,
-0.06077128276228905,
0.00740731181576848,
0.01013620663434267,
0.020677415654063225,
0.011207985691726208,
0.0... |
<p>I am conducting an orthopedic study to predict improvements in activity level (dependent variable) based on a type of self-efficacy scale (the independent variable). There are, however, other predictors that I wish to include in the model. All scales are continuous.</p>
<p>Since this study will be conducted longitu... | g27566 | [
-0.038261592388153076,
0.000673203612677753,
-0.0005476718652062118,
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0.06225433945655823,
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0.004390617832541466,
0.040570106357336044,
0.03832704946398735,
0.06448693573474884,
-0.0038494968321174383,
-... |
<p>Suppose that we are modeling the log-hazard of death using age, gender, bmi, and weight. BMI and weight are correlated. Would it make sense to drop one of these variables from out analysis?</p> | g67836 | [
0.03460798040032387,
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0.00689625833183527,
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0.019882384687662125,
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-0.009390789084136486,
0.020717985928058624,
0.021310975775122643,
0.07914558053016663,
... |
<p>The title says it all. Specifically: given strictly positive real numbers $a_1,\dots,a_T$ and $b_1,\dots,b_T$, I want to sample from $$\mu:=\text{Uniform}(\{p\in[0,\infty)^T : \sum_{t=1}^T a_t p_t = 1\}\cap\{p\in[0,\infty)^T : \sum_{i=1}^T b_t p_t = 1\}),$$ assuming that the intersection is nonempty.</p>
<p>My best... | g67837 | [
0.008624824695289135,
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-0.09066640585660934,
-0.07495151460170746,
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0.01663925312459469,
0.05142045393586159,
0.0002764173550531268,
0.04132434353232384,
0.02158394642174244,
0.01968526467680931,
0.041557736694812775,
-0.0171... |
<p>Here's the thread I got the idea from: <a href="http://www.quora.com/Do-men-have-a-wider-variance-of-intelligence-than-women/answer/Ed-Yong" rel="nofollow">http://www.quora.com/Do-men-have-a-wider-variance-of-intelligence-than-women/answer/Ed-Yong</a></p>
<p>Basically, this is a model that might be able to explain ... | g27568 | [
-0.02632785029709339,
0.05515331029891968,
-0.00497446721419692,
-0.02048518694937229,
0.027366725727915764,
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0.038205213844776154,
-0.027876850217580795,
-0.023877743631601334,
0.03825772553682327,
0.004996732342988253,
0.0055567240342497826,
0.016241956502199173,
-0... |
<p>I was wondering how the Bayesians in the CrossValidated community view the problem of <strong>model uncertainty</strong> and how they prefer to deal with it? I will try to pose my question in two parts:</p>
<ol>
<li><p>How important (in your experience / opinion) is dealing with model uncertainty? I haven't found a... | g27569 | [
0.017623376101255417,
-0.010962815955281258,
0.02346450462937355,
0.028389878571033478,
0.02057356759905815,
0.01974998228251934,
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0.01132875680923462,
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0.03144626319408417,
0.04769764095544815,
-0.05016235262155533,
0.07487975060939789,
0.00508069... |
<p>I am having trouble understanding the following. Let $\mu$ and $\sigma^2$ be the true mean and variance, $\bar{x}$ and $s^2$ the measured mean and variance for a random variable $x$, where $$\displaystyle s^2 = \frac{1}{N+k}\sum_i (x_i-\bar{x})^2.$$ </p>
<ul>
<li>If $s^2$ is an unbiased estimate
of variance then ... | g67838 | [
0.008968375623226166,
0.014694766141474247,
-0.03282324969768524,
-0.0049316538497805595,
-0.012996342033147812,
0.006560815963894129,
0.007152374368160963,
-0.0026297683361917734,
0.009904703125357628,
-0.027963273227214813,
-0.041460003703832626,
0.0374181866645813,
0.0006495469715446234,
... |
<p>Here is an ANOVA model with one between-subject factor (condition; 4 levels) and one within-subject factor (trial_seq; 20 levels).</p>
<pre><code>amod = aov(decision_quality ~ condition*trial_seq +
Error(user_id/trial_seq), data = d.task1)
summary(amod)
</code></pre>
<p>I want to do a pairwise analysis for... | g67839 | [
-0.05535208061337471,
-0.028122875839471817,
-0.0022663671988993883,
-0.09354326128959656,
0.02204453945159912,
-0.011663117446005344,
0.0009176500607281923,
-0.0037047299556434155,
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0.03510859236121178,
-0.004049612674862146,
-0.00493503175675869,
0.04908524081110954,
... |
<p>I have carried out PCA and then clustered the 6 resultant components using K-means clustering technique using SPSS. Normally SPSS adds a class variable for each case indicating its assigned group. </p>
<p>Is there any other method I can "calculate" the class variable (i.e. using component scores and REGR factor sco... | g67840 | [
-0.022815747186541557,
-0.08343170583248138,
0.007432305719703436,
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-0.003436580765992403,
-0.06914741545915604,
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0.025743668898940086,
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0.04806288704276085,
0.04173294082283974,
0.07815385609865189,
0.033... |
<p>I was wondering if there is a way to determine the significance of a covariance? So, if have two vectors of returns, and then calculate the covariance, how do I determine if the sample covariance is significantly different from zero? A professor at the university told me to look for the confidence interval? Can use ... | g67841 | [
0.001002429286018014,
0.008754562586545944,
-0.023838838562369347,
-0.0368470773100853,
0.011440863832831383,
0.029331116005778313,
0.02167852781713009,
0.04275741055607796,
-0.03280085325241089,
-0.008629366755485535,
0.019498903304338455,
0.02976233884692192,
0.020853595808148384,
-0.018... |
<p>I have a spreadsheet with one object per line. Each column contains values that are parameters of my objects (let's say length, width, height, weight, color). I can classify objects based on color and define classes.</p>
<p>Let's say I am blind, and I therefore don't have access to the color parameter. I want to fi... | g17506 | [
0.03964533656835556,
0.0207318477332592,
0.003007934195920825,
-0.023201577365398407,
0.05717889592051506,
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-0.010393152013421059,
-0.022669527679681778,
0.0027728977147489786,
0.05815206468105316,
0.003... |
<p>How I can choose the most optimal parameters for SMOTE in WEKA. More specifically, how should I pick the nearest-neighbours and the SMOTE to apply? I have been using the amount of SMOTE that gives the highest geometric mean and F1 measure but I'm not sure if this is the correct approach.</p> | g67842 | [
-0.026224782690405846,
-0.012173383496701717,
0.001299956813454628,
-0.00421947380527854,
-0.018128888681530952,
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0.03176705911755562,
0.055544737726449966,
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0.06399760395288467,
0.008462228812277317,
0.010071229189634323,
0.07544399052858353,
0.0... |
<p>Suppose I have a dataset $\{y_i,x_i\}$ $i=1,2,...n$. For the response variable, $y_i$ as per quantile regression I have the following likelihood:</p>
<p>$$p(y_i|\beta,\alpha_i,\sigma) =\frac{\alpha_i(1-\alpha_i)}{\sigma}\exp\left(-\frac{\epsilon_i(\alpha_i-I(\epsilon_i<0))}{\sigma}\right) $$</p>
<p>where, $\ep... | g67843 | [
-0.017102325335144997,
-0.07259128987789154,
-0.04073232039809227,
-0.07327263802289963,
0.013490020297467709,
-0.008664529770612717,
0.045764703303575516,
-0.0010300882859155536,
-0.07072540372610092,
-0.01670716144144535,
0.0032265197951346636,
0.04388128221035004,
0.050843171775341034,
... |
<p>I want to perform test to a 10-fold cross validated result like the following to prove my proposed model is better than the baseline.</p>
<pre><code>Baseline,Proposed
0.807,0.901 - won
0.851,0.861 - won
0.840,0.799 - lose
0.817,0.951 - won
0.907,0.951 - won
...
0.827,0.911 - won
</code></pre>
<p>So my question is,... | g67844 | [
0.02736613340675831,
-0.03100578300654888,
0.02105596661567688,
-0.04157283157110214,
0.04127258062362671,
0.015573914162814617,
0.05146871134638786,
0.03376989811658859,
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0.023671556264162064,
0.03912966698408127,
-0.008034205064177513,
0.008371682837605476,
-0.02072... |
<p>I have been reading about VaR scaling in "Market Risk Analysis" by Carol Alexander. It talks about square root of time (horizon) scaling is valid only if returns distribution is normal. </p>
<p>For stable distributions there is a method, Power Law of exponents, to empirically find out exponent of horizon instead of... | g67845 | [
0.02445172891020775,
0.03497403860092163,
-0.03164323791861534,
-0.024303151294589043,
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0.020616954192519188,
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0.014762163162231445,
0.0029569293837994337,
0.022069979459047318,
0.015893056988716125,
... |
<p>I am working with a structural time series model in R using dlm that has both a stochastic (slope and intercept) local trend and two trigonometric seasonal components (sin and cos pairs). I have difficulty balancing the two. </p>
<p>The main frequencies in my problem arise from several diurnal and semi-diurnal tid... | g27577 | [
-0.013472926802933216,
-0.06769555062055588,
0.023569775745272636,
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0.02387663908302784,
0.002271195873618126,
0.049375634640455246,
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0.039441004395484924,
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0.05266067013144493,
0.028932305052876472,
0.05903298407793045,
0.0133... |
<p>Assuming I have an unordered set of tuples of the form:</p>
<p>$(a, b)$ </p>
<p>How can I order the set so as to optimize the following equation:</p>
<p>$\sum_{i=1}^n\sum_{j=1}^{i-1}(a_i*b_i)(1-b_j)$ </p>
<p>For small numbers of $n$ I can simply calculate the result for each ordering. However, as this is $O(n!)$... | g27579 | [
-0.040639519691467285,
0.07579333335161209,
-0.01673179119825363,
-0.009474185295403004,
-0.022121796384453773,
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-0.0055686854757368565,
-0.03818989172577858,
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-0.028302667662501335,
-0.018971974030137062,
-0.007173005025833845,
-0.00831916928291320... |
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