question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Let $A$ be a Beta distributed random variable, $\mathcal B(a,b)$, with probability density function:
$$
f(x)= \frac{Γ(a+b)}{Γ(a)Γ(b)}*x^{(a-1)}*(1-x)^{(b-1)},
$$
where $0<x<1$. Suppose that $B$ is a random variable, $\mathcal B(a+1,b)$. Write down its probability density function $g(x)$.</p> | g28652 | [
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<p>In my attempt to forecast sales demand by month utilizing the last 3 years of history to predict balance of the year, <code>ets() from forecast() package</code> yields an answer for some time series but not others. I'm following Dr Hyndman's presentation on best fist ets() function. </p>
<p>I understand while the ... | g68576 | [
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<p>Would you consider the HBM vs EB to be two alternatives in which the hyperparameters are "in the game" of being sampled/estimated/etc.? There is clearly a connection between these two.</p>
<p>Would you consider HBM more "fully Bayesian" than EB? Is there some place where I can see what are the differences between b... | g68577 | [
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<p>(See note**)</p>
<p>I am attempting to put together an infograph and am almost done collecting all the data I need. </p>
<p>In addition to the base raw data collected, I'd like to add something I'm calling parallel stability and differential volatility. Here's what I mean:</p>
<ul>
<li>First, take a look at these... | g28655 | [
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<p>How do I generate random nos based on say <em>k</em> moments? (no other constraints on support)
When <em>k = 2</em>, we generate random nos. from a normal distribution defined by the 2 moments. Can we generalize this idea to an arbitrary <em>k</em>.</p>
<p>A related question: Is normal distribution the only (known)... | g68578 | [
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<p>I am trying to check the significance of counselling in the technique for inhaler usage (rotahaler only) at different points of time in same subjects. </p>
<p>The subjects' baseline technique will be assessed using a checklist scoring : zero for incorrect/ missed step and 1 for correct step. The total score is 8 (i... | g68579 | [
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<p>Consider the autoregressive model,</p>
<p>$\left[ \begin{array}{l}
y^{\ast}_t\\
x_t^{\ast}
\end{array} \right] = \left[ \begin{array}{l}
a_{11}\\
a_{21}
\end{array} \begin{array}{l}
a_{12}\\
a_{22}
\end{array} \right] \left[ \begin{array}{l}
y^{\ast}_{t - 1}\\
x^{\ast}_{t - 1}
\end{array} \right] +... | g68580 | [
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<p>I'm looking for a way of integrating the following formula where <em>ppf()</em> is the percentile point function for the standard normal distribution, <em>cdf()</em> is its inverse, and <em>A</em> is a constant:</p>
<p>\begin{equation}
\int_{0}^{1} cdf(ppf(x)-A)dx
\end{equation}</p>
<p>I can do it with a monte car... | g68581 | [
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<p>I read in many books or notes online that (1)volatile series do not differ significantly from white noise and that (2)their squared values will exhibit correlation.
Although I agree with (2), I can't seem to agree with (1). I used the tsdisplay function from forecast package to plot the acf of SP500(MASS) and bmw(ev... | g28661 | [
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<p>I'm trying to understand how logistic regression uses the binomial distribution. </p>
<p>Let's say I'm studying nest success in birds. The probability of a nest being successful is 0.6. Using the binomial distribution, I can calculate the probability of r successes given n trials (numbers of nests studied).</p>
<p... | g68582 | [
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<p>I'm having trouble deriving the PDF for the following problem (from the book <em>Doing Bayesian analysis with R and BUGS</em>):</p>
<blockquote>
<p>Consider a spinner of the kind often found with board games, but with
a log10 scale from 1 to 100 (covering 0 to 360 deg). The spinner is fair, so any value is equa... | g49729 | [
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<p>I am trying to fit a GLMM for binary responses and I want to model the covariance matrix of random effects, say bigE, with some covariates. To do this, we decomposed the bigE into two different matrices, bigT and bigD, as seen in the following code.</p>
<p>When I run the following code, it gives me the following er... | g68583 | [
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<p>I'm trying to look at multiple comparisons (across levels of my between subjects factor) for a model with one between-subject factor and one within-subject factor. I was trying to use TukeyHSD on an aovlist object, and then found out that I couldn't do that.</p>
<p>After some browsing, I found how to do what I want... | g68584 | [
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<p>I have a score of some feature, $F_1$ and $F_2$ where this score is the logarithm of probability.</p>
<p>This score is very low and very sparse, for example i have:</p>
<p>$F_1$ with score $-800$</p>
<p>$F_2$ with score $-3000$</p>
<p>I need to get the probability with the exponential function and make the sum o... | g68585 | [
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<p><strong>The situation:</strong> I'm struggling with a predictive analysis of food sales prices using a generalized linear model. My dataset contains different kinds of food (cheeses, vegetables, meats, spices etc.) and hence I am splitting the dataset completely by these kinds when doing the analysis, because they a... | g28664 | [
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<p>I just discovered by mistake that raw data and the same z scored data produces the same correlation. Why is this? Can someone walk me through the logic?</p>
<pre><code>> x = c(2,4,6,7,8,3,6,8,9)
> y = c(3,3,5,7,6,8,9,10,5)
> cor(x,y)
[1] 0.3780247
> zx = (x-mean(x))/sd(x)
> zy = (y-mean(y))/sd(y)
>... | g28665 | [
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<p>I'm posting this in this forum because I think the question is related to stats. If it's not, I'm fine with it being moved over to Stackoverflow.</p>
<p>I have data in R and am trying to fit a linear model to it. Here's what the data looks like (sorry that it's not reproducible, it's just too much data to type out)... | g68586 | [
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<p>I have a variable called "obs" and from this variable I generated a new variable called "obs_sub" by excluding all observations for which a dummy variable is equal to one. Now what I want to know is if I remove these observations whether the mean of the sub-sample is equal to the mean of the sample. This is my null ... | g68587 | [
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<p>This is a portion of a tutorial from the <a href="http://www.bristol.ac.uk/cmm/" rel="nofollow">Centre for Multi-Level Modeling</a> regarding random intercept models. </p>
<p>Can anyone explain why this scenario is so? It seems like by the logic given and that the u_j (group effects) are moved toward zero by adding... | g68588 | [
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... |
<p>Consider this standard linear regression model:</p>
<p>$Y = \beta_0+\beta_1X_1+\cdots+\beta_pX_p+\epsilon$</p>
<p>I've loaded such a dataset into Stata 12.0, so I have some variables $y,x_1,x_2,\dots,x_p$. How do I produce a plot, like I would with <code>. scatter y x</code> for a simple linear regression model? <... | g68589 | [
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<p>I'm studying several schemes on classifying patients about their survival time. Let me illustrate the problem with supposing I have just two schemes.</p>
<p>Let's suppose that Scheme 1 put the patients in 5 groups, and Scheme 2 put the patients in 5 groups too (but the groups have different compositions, for exampl... | g68590 | [
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<p>If $X_1,X_2...X_N$ are independent Poisson variables with parameters $\lambda_1,\lambda_2...\lambda_3$, then given $\sum_iX_i=N$, we have that </p>
<p>$X_i \sim \mathrm{Binom}(N,\frac{\lambda_i}{\sum_j\lambda_j})$ (straight from <a href="http://en.wikipedia.org/wiki/Poisson_distribution#Related_distributions" rel="... | g49808 | [
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<p>I currently working in a multivariate logistic model but I have a problem regarding the sample size of my observations:</p>
<p>-The "success" (1) event group has a sample size of 249 distinct observations
- The "non success" (0) event group has a sample size of 48,957, and it's a significant part of the population,... | g68591 | [
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<p>I am trying to use Stata for the first time to calculate Spearman's Rank Correlation for differences in weight and hemoglobin between annual visits for a small dataset. Do I enter the differences with the negative sign directly or do I square the differences first?</p> | g68592 | [
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<p>My question is strongly related to this one: <a href="https://stats.stackexchange.com/questions/11384/pca-and-component-scores-based-on-a-mix-of-continuous-and-binary-variables">PCA and component scores based on a mix of continuous and binary variables</a>.
I will basically use the same code, but add a new nominal f... | g28668 | [
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<p>I am performing simulations while measuring a quantity A which depends on the parameter B. I make N independent measurements of A for given values of B. I can then calculate the mean to get an estimation of what the real value of A is. My question is about the error.</p>
<p>I can calculate the 95% confidence interv... | g68593 | [
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<p>I'm trying to write a program to detect water bubbles in heated oil. I've applied a canny edge detection filter to the image and the results look like the following:</p>
<p>No bubbles: <a href="http://imageshack.us/photo/my-images/20/nobubbles.png/" rel="nofollow">http://imageshack.us/photo/my-images/20/nobubbles.p... | g68594 | [
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<p>I know that R is not particularly helpful for analysing large datasets given that R loads all the data in memory whereas something like SAS does sequential analysis. That said, there are packages like bigmemory that allows users to perform large data analysis (statistical analysis) more efficiently in R.</p>
<p>I w... | g28669 | [
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<p>I am working on a project, and I am totally new to statistics. I have sales data for last two years at week level, along with other variables like temperature, holiday (TRUE/FALSE), where holiday are nominal variables. I have to do forecasting for the next 52 weeks. I have the following questions:</p>
<ol>
<li>Can ... | g68595 | [
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... |
<p>Sorry for a newbie question. I haven't quite understood the correct meaning of what it means to take the partial derivative of a cost function with respect to the parameters, say theta. Suppose these parameters include 2 arrays of dimensions axb and cxd.</p>
<p>When we do stochastic gradient descent, then what will... | g68596 | [
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0.05402316898107529,
0.01842251978814602,
0.010039... |
<p>I have a water quality data (<strong>value</strong>) measured 10 times (every month - <strong>data</strong>) on three <strong>depths</strong> (shallow, medium, deep) in five <strong>location</strong> (A, B, C, D, E):</p>
<p><img src="http://i.stack.imgur.com/9ANC6.png" alt="enter image description here"></p>
<p>I ... | g28672 | [
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0.045836541801691055,
0.09684833139181137,
0... |
<p>How do you choose the order p and q for a ARMA(p,q) process for modeling a time series?</p>
<p>Can that be told from ACF or PACF alone, just like for a AR(p) or MA(q) process?</p> | g68597 | [
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<p>I have a four columns data in a table that looks something like this :</p>
<pre><code>Item Result_1 Result2_ Result3 Result_4
========================================
A 77.2 20.2 10.2 2.1
B 32.1 16.1 50.3 4.1
C 40.3 90.2 7.1 6.2
</code></pre>
<p>The problem I ha... | g49809 | [
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0.026320137083530426,
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<p>I'm trying to use some code that includes Gamma priors for Poisson (rate) and Exponential (rate) distributions. I want to make the priors noninformative. I read that using a Gamma(0,0) is equivalent to the Jeffreys prior, which is noninformative. Is this true? Can anyone suggest any references for this? I though... | g68598 | [
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<p>Suppose I have a relatively large number of samples (~1k) drawn from a series (~40) of increasingly long-tailed distributions (going from approximately normal to approximately log-normal). I want to estimate the mean and its uncertainty for these distributions, which I do using jackknife resampling because the sampl... | g68599 | [
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<p>For my survey data analysis, I ran an Ordinal Logistic regression using the 'polr' function.
The summary of the regression is as follows:</p>
<p><img src="http://i.stack.imgur.com/csKGq.png" alt="enter image description here"></p>
<p>My question is:</p>
<ol>
<li>Do I need to standardize my beta values?</li>
<li>... | g28676 | [
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<p>I'm working through Rasmussen's Gaussian Processes book, and I have a question about the possibility of optimizing additional basis function hyperparameters (in section 2.7 <a href="http://www.gaussianprocess.org/gpml/chapters/RW2.pdf" rel="nofollow">http://www.gaussianprocess.org/gpml/chapters/RW2.pdf</a>).
The tex... | g28677 | [
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... |
<p>I used to know that Naive forecast is equal ( ft is the same like the previous year)
Someone told me that there is another equation used in the sales which is equal
( current year - previous year)/ previous year
Is it true?</p> | g28678 | [
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<p>lets say we have this: </p>
<blockquote>
<p>model2 <- lmer(milk.amount~(1|cow), data=milk, REML=FALSE)</p>
<p>model1 <- lmer(milk.amount~(1|cow), data=milk)</p>
<blockquote>
<p>summary(model2)</p>
<p>Linear mixed model fit by maximum likelihood ['lmerMod']</p>
<p>Formula: mi... | g68600 | [
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<p>I've collected data measuring several different parameters in several subjects at two time-points (t1 and t2).</p>
<p>X and Y are meausurements of two anatomical structures; X is an area measured in mm2, Y is a volume measured in mm3. For each one I can describe at least 4 variables: measuments at t1 and t2 (eg. X1... | g68601 | [
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<p>What is the difference between finite and infinite variance ? My stats knowledge is rather basic; Wikipedia / Google wasn't much help here.</p> | g68602 | [
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<p>I am new to Neural networks and I am trying to build a custom neural network using the NN toolbox in MATLAB.I am using the "create custom neural network function".</p>
<p>Now, I find the neural network interpretation of MATLAB very confusing.</p>
<p>I am looking to create a network which looks like this - </p>
<p... | g68603 | [
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<p>After I read chapter 7 of the new edition of Bayesian Data Analysis<sup>1</sup>, I have come to understand that while Information Criteria like DIC and WAIC are: </p>
<ul>
<li>A way measuring the adjust of the model and penalize by the effective number of parameters.</li>
</ul>
<p><br />They are also:</p>
<ul>
<l... | g68604 | [
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<p>I have collected ratings on a scale from 0 to 100 for two different conditions: A and B. I want to show now, that the ratings collected under both conditions are very similar and that their range overlap.</p>
<p>How can I do that best? I thought about drawing a box plot for both conditions, but I would prefer a num... | g68605 | [
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<p>Suppose you have a relatively small random sample and have a corresponding model
$\ Y$ ~ $\operatorname{Bernoulli}(p_i) $</p>
<p>$\ \operatorname{logit}( \hat{p_i} )=\hat{\beta}*X$ and now want to draw a sample of a fixed size in order to maximize the accuracy over the entire universe of the $\hat{p_i}$ generated ... | g68606 | [
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<p>I'm trying to use rjags to predict what the curve-maximums will be for different groups of incomplete data (one metric x and one metric y). Here is an example of the indata:</p>
<p><img src="http://i.stack.imgur.com/315aR.png" alt="enter image description here"></p>
<pre><code>in.data <- structure(list(x = c(10... | g31687 | [
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<p>Good Day All,</p>
<p>I am attempting to compare three diagnostic tests against a gold-standard and for simplicity sake, let us have all the outcomes be binary (disease/no disease).</p>
<p>In this study study, all participants received the four tests (e.g. everyone got the gold-standard and three competing tests).<... | g35180 | [
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<p>Say, I have a biomarker that is strongly associated to a gene. This biomarker is also strongly associated to another trait, like glucose, but the gene is not. </p>
<ul>
<li>If I perform a regression between the glucose and biomarker + gene I get the biomaker and gene both significant: Is this a spurious effect? </l... | g28688 | [
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<p>I have an algorithm that take as input some data (that are continuously arriving) and 3 or 4 parameter values that should be specified by the user. At the and of execution (or periodically during execution) we can evaluate the performance to see if the chosen parameter values were good or not, but the evaluation fun... | g28689 | [
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0.069... |
<p>I've subsetted and plotted my unweighted data, but I don't see how to make use of my weighting variable "FactBx$expwgt"</p>
<pre><code>#####################################################
plot( density(FactB1$BAV_DIST),
#### xlim=range( c(FactB1$BAV_DIST, FactB2$BAV_DIST, FactB3$BAV_DIST) ),
xlim = c(0, 10... | g68607 | [
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0.03873... |
<p>I have a question on the term used for the type of the item that I would like to use and how it is "usually" analysed.
Let's assume that we have two items and the one is linked to the other, namely, the one is the answer in a multiple choice question and the second on is quantifies an attribute, for example, "did yo... | g68608 | [
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<p>In reviewing a paper, the authors state, "Continuous outcome variables exhibiting a skewed distribution were transformed, using the natural logarithms, before t tests were conducted to satisfy the prerequisite assumptions of normality."</p>
<p>Is this an acceptable way to analyze non-normal data, particularly if th... | g68609 | [
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<p>Whilst reading up on the Deep learning literature, I noticed that a few variations on the standard network structure that were created specifically to better model "Natural/Real Images". For example, <a href="http://www.cs.toronto.edu/~ranzato/publications/ranzato_aistats2010.pdf" rel="nofollow">this paper</a> says ... | g28691 | [
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<p>Recent research has attempted to determine if certain psychological constructs are latently dimensional or taxonic (i.e., including taxons or classes). For example, researchers may be interested in finding out if there is a certain "class" of people who are more likely to develop chronic pain after an injury, or if ... | g68610 | [
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... |
<p>So I'm currently training a stack of RBMs (Restricted Boltzmann Machines), eventually to be build into a DBN (Deep Belief Net), on a set of gray-scale images featuring objects placed in different locations on a complex background. </p>
<p>After training for a good long while, I tried generating from the RBMs and fo... | g28692 | [
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<p>I have a panel chart composed of 4 panels, each with 12 bars that essentially show data from a pivot table. The default layout has the first 11 rows show individual points, with the 12th row showing a total of the entire column. Similarly, the final column shows a total of the 3 preceding columns. The result is t... | g28 | [
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0... |
<p>I need to find a symmetric low-kurtosis distribution class, which includes the uniform, the triangular and the normal Gaussian distribution. The Irwin-Hall distribution (sum of standard uniform) offers this characteristic, but is not treating non-integer orders $N$. However, if you e.g. simply independently sum up e... | g68611 | [
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<p>Hi I am trying to calculate the t-statistic for a correlation coefficient between two vectors $x$ and $y$.</p>
<p>The individual vectors shows signs of autocorrelation. I have made use of the formula:</p>
<p>$\frac{r}{\sqrt{(1-r^2)(n-2)}}$</p>
<p>but I'm not sure this is the correct way of solving the problem.</p... | g28694 | [
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<p>I'm currently working with a data set where there is a control group and an intervention group. There are a couple of data points where we're interested in seeing if the intervention group has a statistically significant difference in effect (basically is $x_2 - x_1$ in intervention different than $x_2-x_1$ in contr... | g68612 | [
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0.0... |
<p>I want to run a simulation in which I want to find out whether there is a relation between the independent variable $x_t$ and the dependent variable $y_t$. I.e., in the following regression I want to find out if $\beta$ is signficantly different from zero:</p>
<p>$$ y_t = \beta x_t + \epsilon_t. $$</p>
<p>In empir... | g28695 | [
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0.022919300943613052,
0.08029201626777649,
0.0035607151221483946,
-0.... |
<p>So I have a data set like so:</p>
<pre><code>Email Posted Received Platform
ss104@gmail.com 3/20/2012 1:11 Tue, 20 Mar 2012 01:07:05 -0700 (PDT) Wikipedia
ss104@gmail.com 3/20/2012 1:11 Tue, 20 Mar 2012 01:07:22 -0700 (PDT) Mailing list
ss104@gmail.com 3/2... | g10882 | [
0.0224857646971941,
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<p>Let the random point $(X,Y)$ be uniformly distributed on the unit disc $D=\{(x,y):x^{2}+y^{2}<1\}$.
Show that the polar coordinates $R\in [0,1)$ and $\theta \in [0,2\pi)$ of the point are independent.</p>
<p>Can you help me with this exercise please?</p> | g68613 | [
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<p>This is continuation for a series of questions (<a href="http://stackoverflow.com/questions/10330314/pointrange-plot-with-boxplot-type-grouping">1</a>, <a href="http://stats.stackexchange.com/questions/27248/monte-carlo-nonparametric-confidence-intervals-for-mean-estimate">2</a>). I have a data set from an experimen... | g28703 | [
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0.0098... |
<p>I have different models namely AR, ARMA, ARIMA for different time series (in data set of 4449)
stationary-3096, Non stationary-1353 , why this classification appears to be? </p>
<p>If I have $AR(p=1-5)$ and $AR(p >5)$ what does my data tell ?,</p>
<p>I have many time series which follows ARMA-1239 best models, ... | g68614 | [
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0.06422407180070877,
0.04037291184067726,
-0.01... |
<p>Given a weighted sum of regression trees, is there an efficient algorithm to find <strong>all</strong> local maxima ?</p>
<p>(I would tend to think that a gradient based method will find <strong>some</strong> maxima but it is not entirely clear to me how to ensure that one will find all of them)</p> | g28705 | [
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<p>I really want to learn about Bayesian techniques, so I have been trying to teach myself a bit. However, I am having a hard time seeing when using Bayesian techniques ever confer an advantage over Frequentist methods. For example: I've seen in the literature a bit about how some use informative priors whereas others ... | g35986 | [
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<p>This is probably a simple question.</p>
<p>I'm studying events which have N outcomes, of which exactly one is correct. N is very large, more than a billion (and is known). There are many possible events, some of which are tested multiple times.</p>
<p>I would like to test the following model: a given event is te... | g38649 | [
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0.0291... |
<p>I have a dataset with between 10,000 and 100,000 feature values. The number of datapoints is between 1,000 and 10,000. I want to perform a LASSO on this dataset but can't really find any good software to do so. Does anyone have any suggestions?</p> | g28706 | [
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<p>This is the PDF that I am dealing with:</p>
<pre><code>fx = 0.3 if (0<=x<1)
0.1 if (1<=x<2)
0.25 if (2<=x<3)
0.15 if (3<=x<4)
0.2 if (4<=x<5)
0 otherwise
</code></pre>
<p>I have to write a function <code>gen_xy</code> that will generate a sequence of points <code>(X,Y)</code> unifo... | g21394 | [
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<p>I am new to evolutionary algorithm. I have studied Covariance Matrix Adaptation Evolution Strategy. I am not good at statistics. So could you please explain me in simple language (I mean not too many equations)</p>
<ol>
<li>What is CMA-ES?</li>
<li>How does it work?</li>
<li>Why is it superior to other strategies?<... | g68615 | [
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... |
<p>I have a multi-class dataset like the following (a,b,c,d are features and e is the class (it can be 0,1 and 2)).</p>
<pre><code> a b c d e
1 1 1 2 2 1
2 1 2 4 2 0
3 1 2 4 2 0
4 2 2 2 2 0
5 2 1 2 2 2
</code></pre>
<p>I am trying to use mlogit package in order to see which column is more important but I... | g68616 | [
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0.06333264708518982,
0.15262152254581451,
0.01... |
<p>How do you show that if my model parameter $\theta$ (scalar) is U-estimable (i.e. if there exists an unbiased estimator of $\theta)$, then $\theta$ is identifiable? This makes sense intuitively, but I'm not sure how to prove it.</p> | g2311 | [
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0.06504256278276443,
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0.04060480371117592,
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0.05616... |
<p>Suppose we consider a linear normal regression
$y\sim$Normal($\mu,\sigma$) and $\mu=a+bx$. I have seen documentations for methods for obtaining a confidence interval for $x$ for a specific mean value of $y$. Suppose instead of the mean $y$, I want a confidence interval in $x$ for top 5%ile of $y$ (e.g., so that pred... | g68617 | [
0.04455714672803879,
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0.04153425991535187,
0.07870695739984512,
0.03990919142961502,
-0.041... |
<p>How do I get better forecasts for my model? Is the plot supposed to look like this? I am using the code:</p>
<pre><code>fit <- auto.arima(blah)
fcast <- forecast(fit,100)
</code></pre>
<p><img src="http://i.stack.imgur.com/TeiGU.png" alt="enter image description here"></p> | g68618 | [
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<p>I am developing network meta-analysis BUGS model that I will use to compare Hazard Ratios in studies that assume Box Proportional Hazard model. </p>
<p>As input I am given pairs: (log HR, its standard error) that measure magnitude of the effect of difference between two treatments. Naturally I assume normal distri... | g68619 | [
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0.01496527437120676... |
<p>I am currently rather confused about the design type for my study.</p>
<p>I am looking at a number of measures pre and post intervention with control group in a community sample. The sample collected was not through randomization. Is the design type quasi-experimental? What kind of statistics can i use for this des... | g68620 | [
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<p>I have more of a programming background, and I am fairly new to statistics. I am currently trying to solve some sample exercises to get more familiar with data science / modelling. </p>
<h3>Problem Background</h3>
<p>A user posts a request on a forum. Considering number of responses / number of up votes / users' r... | g28712 | [
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<p>I've been reading an <a href="http://queue.acm.org/detail.cfm?id=2492433" rel="nofollow">article on ACM queue</a>, and got confused by figure 6 (latency distribution of a push-only workload), where the authors used the y axis to display the latency, and the x axis to denote the quantile. </p>
<p><img src="http://i.... | g68621 | [
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0.0067643471993505955,
0.06007090210914612,
-0.0424... |
<p>I am working Automatic Email routing. My historical data set has Email Description,Division and Category. There are around 20 division and 150 categories.</p>
<p>I have built one vs. all classifier (RTextTools - SVM) for 20 divisions and trained 20 classifier and when the new email comes in , my container(SVM Model... | g68622 | [
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0.04171482473611832,
0.09501631557941437,
0... |
<p>Let A be a random variable hence a node in my bayesian network. I wish to apply some function on A and then connect it to some other node in the network. So how to do that?</p> | g68623 | [
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0.035103689879179,
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<p>I'm trying to follow the proof from question 1b out of the book "50 Challenging Problems in Probability" by Mosteller. The problem states:</p>
<p>A drawer contains red and black socks. When two socks are drawn at random, the probability that both are red is $1/2$. How small can the number of socks in the drawer be ... | g68624 | [
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0.0030641895718872547,
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... |
<p>I am designing RBM with CD training methodology in MATLAB. CD is an unsupervised learning algorithm, so I do not need to use any label information included in input. Does that make sense? </p> | g28716 | [
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<p>I'm linearly regressing some response <code>y</code> onto some predictor <code>x</code>. I'm interested in knowing for what <code>x</code> does <code>y = 0</code>.</p>
<p>I can think of two ways to do this. Let me illustrate with some sample data:</p>
<pre><code>x <- 1:10
y <- 20 - 2 * x + rnorm(10)
</code><... | g68625 | [
0.027235709130764008,
-0.01978898048400879,
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0.055402614176273346,
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0.016754424199461937,
0.03364958241581917,
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-0.0867733284831047,
-0.009398427791893482,
0.05704311653971672,
0.03558671474456787,
0.0036... |
<p>I'm trying out the boot() function for internal validation of a logistic glm model using the AUC (aka c-statistic) as my performance measure. My problem is that depending on the dataset I use, sometimes the function gets "50 or more warnings," all of which are of this type:</p>
<pre><code>Warning messages:
1: In wi... | g68626 | [
-0.0022216439247131348,
0.03312916308641434,
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0.07897703349590302,
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0.0422738678753376,
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-0.06850313395261765,
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0.04524196311831474,
0.05895109102129936,
0.03... |
<p>Could someone please explain in plain English (preferably without using the word paired) or by using examples when it is appropriate to use <code>wilcox.test(x,y,paired=TRUE)</code>?</p>
<p>I have read the R documentation and various links on google and I'm not 100% sure that I get it. If someone would be kind enou... | g28719 | [
0.04181313142180443,
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0.02396463416516781,
-0.026975765824317932,
... |
<p>I would like to create a power law distributed series with 100 numbers and a minimum value of 10. </p>
<p>I could not find any command in R that directly does this. What is the easiest way?</p> | g28720 | [
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0.024038439616560936,
... |
<p>What is your or an offical (please provide link to citation) definition of range AND interval <strong><em>_</em></strong>? </p>
<p>Or perhaps put in another way: what is the major important difference between the two terms <strong><em>_</em></strong>?</p>
<p>My perception is the following:</p>
<blockquote>
<p>S... | g68627 | [
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0.008169788867235184,
0.026231586933135986,
0.05509323254227638,
-0.0258... |
<p>I'm kind of a noob to EFA and am trying to use the FANode object in Python. This is from the MDP library. I am using it on survey data to see which variables are tied together. Whenever I run it on my data, I get the following error:</p>
<pre><code>mdp.NodeException: The covariance matrix of the data is singular. R... | g21186 | [
0.018186243250966072,
-0.0033844131976366043,
0.02318904735147953,
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0.047526951879262924,
0.03423153981566429,
0.031568773090839386,
0.0334724485874176,
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0.004946921952068806,
0.023575037717819214,
-0.02146579511463642,
0.04281385987997055,
-0.01346... |
<p>I am having trouble training a model for nested data about house prices. Lets say my data looks like following:</p>
<pre><code> logPrice bedCount bathCount city
0.6517920 4 2-3 Redwood City
0.4402192 1 1-2 South San Francisco
0.5922396 2 1-2 ... | g68628 | [
0.02310747653245926,
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0.008314336650073528,
0.01607884280383587,
0.00986472424119711,
0.04025166109204292,
0.028305642306804657,
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-0.04788762331008911,
-0.05461835488677025,
0.07882551848888397,
0.04916665703058243,
0.010100... |
<p>Statistical model for a Completely Randomized Design:</p>
<p>$$y_{ij}=\mu+\tau_{i}+\epsilon_{ij}\quad i=1,2,\ldots,a;
j=1,2,\ldots,n$$</p>
<p>where,</p>
<p>$y_{ij}$ is the $j$th observation of $i$th treatment effect</p>
<p>$\mu$ is the overall mean</p>
<p>$\tau_{i}$ is the $i$th treatment effect</p>
<p>$\epsi... | g29537 | [
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0.040981490164995193,
0.019485624507069588,
0.0640334039926529,
0.0... |
<p>I'm trying to predict a price for an item on the website. I'm interested in classifying the prediction as good or bad. There are two approaches that I can think of, and I'm wondering which one is better and why:</p>
<ol>
<li><p>See what percent of the time the predicted value falls within a certain distance away fr... | g68629 | [
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<p>I'm aware of several related questions here (e.g., <a href="http://stats.stackexchange.com/questions/14830/hypothesis-testing-terminology-surrounding-null">Hypothesis testing terminology surrounding null</a>, <a href="http://stats.stackexchange.com/questions/6225/is-it-possible-to-prove-a-null-hypothesis">Is it poss... | g17705 | [
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<p>I feel like these questions should be related to the binomial and geometric distributions, but I can't quite work out how.</p>
<p>Suppose I do sequential independent Bernoulli trials each with success probability $p$. Rather than fixing the number of the trials, as with the binomial distribution, I want to fix the ... | g68630 | [
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<p>Overfitting is when we have a model which has memorized the training data and does not perform well in real-world cases.</p>
<p>Okay, say that I had some training points which look like this:</p>
<p><img src="http://i.stack.imgur.com/NEzOx.png" alt="enter image description here"></p>
<p>What if the red curve was ... | g68631 | [
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<p>What kind of normalization scheman is required for the best of NN algorithms? I saw some people just give the data to signum function before passing to NN and some of those process data by regular standardization. What is the best result method?</p> | g68632 | [
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<p>Suppose one has two features: color = {R, G, B} and t-shirt size = {S, M, L} and wants to regress these features on the probability of a sale, call it p. So the model is p ~ color + size.</p>
<p>Now, the design matrix will have an intercept, and colors can be represented as</p>
<pre><code>R -> [1 0 0]
G -> [... | g68633 | [
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<p>my problem is as follows. I have a simulation of a neural network which creates activity patterns, learns them and then tries to retrieve previously learned patterns one by one. The performance of these retrievals (=remembering) is the result I'm interested in.</p>
<p>Simplified, this is how it works (I used fictiv... | g28728 | [
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<p>I have a function $f$ that takes $N$ real-valued inputs and is very expensive to compute. I am studying the properties of $f$ by generating samples. Each input $n$ has a range of values $(n_{min}, n_{max})$ that it can take on.</p>
<p>Let's say that due to time constraints I can only generate 1000 samples. Is it "b... | g28729 | [
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<p>In layman's terms, what is the difference between predicting and explaining in statistics? I was looking for the differences between AIC and BIC and found <a href="http://stats.stackexchange.com/questions/577/is-there-any-reason-to-prefer-the-aic-or-bic-over-the-other">this post</a> with an answer stating:</p>
<bl... | g49292 | [
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<p>It's well known that language can be modeled by Multinomial distribution and Multiple Bernoulli distribution.</p>
<p>So far I don't see any advantage of Multiple Bernoulli distribution representation over Multinomial representation.</p>
<p>Both models equal computationally, Multinomial considers the number of occu... | g68634 | [
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