question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>Jon and Frank ordered 2 footlong sandwiches, but instead got 4 6-inch sandwiches. Jon had ordered spicy italian, and Frank chicken teriyaki. The sandwiches aren't labeled and are wrap, so they can't tell which sandwiches are which.</p>
<p>What would be the odds of Jon picking the 2 sandwiches that are are his own? ... | 72,508 |
<p>When assessing model performance, one would like to separate prediction errors due to limitations of the model from those errors due to intrinsic noise. For example, in noisy data, AUC in an ROC curve can be less than 1.0 even when using the "true" model. What are some approaches to get a quantitative estimate of ... | 37,728 |
<p>I'm reading a paper which claims that</p>
<p>$$\hat{X}_k=\frac{1}{\sqrt{N}}\sum_{j=0}^{N-1}X_je^{-i2\pi kj/N},$$
(i.e. the Discrete Fourier Transform, DFT) by the C.L.T. tends to a (complex) gaussian random variable. However, I know this isn't true in general. After reading this (fallacious) argument, I searched ov... | 34,463 |
<p>I'm studying an online course with about 3000 students who each took several quizzes and I'm trying to apply Item Response Theory (using the <a href="http://cran.r-project.org/web/packages/ltm/index.html" rel="nofollow">ltm package in R</a>) to model the questions, determine which items are most or least important ... | 34,464 |
<p>The <code>C5.0</code> classification model was used in this 4-class problem data with $N_{train}$=165, $P$=11, using <code>caret</code> R-package by running the code below. The winnowing option was tuned over in the model, which is a kind of feature selection approach. This excerpt I quote regarding winnowing from t... | 72,509 |
<p>Estimating parameters using maximum likelihood estimation (MLE) involves evaluating the likelihood function, which maps the probability of the sample (X) occurring to values (x) on the parameter space (θ) given a distribution family (P(X=x|θ) over possible values of θ (note: am I right on this?). All examples I've s... | 34,467 |
<p>Suppose we have a first differences regression with a bounded response variable,
$$\Delta y_{i} = \beta_1 \Delta X_{i}+\Delta\epsilon_i.$$ For example, suppose $y_{it} \in [0,1]$ where $y_{it}$ could represent participation of a population on a given survey, or the pass rates of students on a standardized test in a... | 30,848 |
<p>I have a data of sea levels from a particular station from 1940 till today. The linear regression on the data from 1940-1980 resulted in a slope of 3. The linear regression on the data from 1980-2010 resulted in a slope of 4.</p>
<p>What test can be used to establish whether the increase in the slope is significant... | 34,472 |
<p>I am familiar with notation such as:</p>
<p>\begin{align}
y_{ij} &= \beta_0 + \beta_i x_{ij} + u_j + e_{ij}\\
&= \beta_{0j} + \beta_i x_{ij} + e_{ij}
\end{align}
where $\beta_{0j}=\beta_{0}+u_j$, and</p>
<p>\begin{align}
y_{ij} &= \beta_0 + \beta_1 x_{ij} + u_{0j} + u_{1j} x_{ij} + e_{ij} \\
&= \b... | 72,510 |
<p>In market research I'm building a logistic regression model to estimate the likelihood that clients may change banks. The proportion of events is roughly 10% in my sample.
From university I remember that a proportion of events that is too small introduces bias into the estimate. Or is it the standard error that gets... | 72,511 |
<p>I recently did some maximum likelihood estimations where the dependent variable justified the use of a normal distribution. Now, however, the dependent variable has a skewness of 0.4 and a kurtosis of 1.5 and also looks quite strange.</p>
<p>Now my question is: How to choose/find an appropriate distribution? I read... | 72,512 |
<p>What is the meaning of <code>t value</code> and <code>Pr(>|t|)</code> when using <code>summary()</code> function on linear regression model in R?</p>
<pre><code>Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 10.1595 1.3603 7.469 1.11e-... | 72,513 |
<p>I want to assess the effect of temperature on fish mortality. Both variables are time series, so the residual will be autocorrelated. Is there a regression method to deal with that?</p>
<p>Any advice will be appreciated</p> | 72,514 |
<p>I'm cross validating a model that's trying to predict a count. If this was a binary classification problem, I'd calculate out-of-fold AUC, and if this was a regression problem I'd calculate out-of-fold RMSE or MAE.</p>
<p>For a poisson model, what error metrics can I use to evaluate the "accuracy" of the out-of-sa... | 5,455 |
<p>I have the following joint density:</p>
<p>$p(x_1,x_2,y_1,y_2) \propto \exp\left(−\left(x_1^2+x_2^2+c_1(y_2-y_1)^2+c_2(y_2-y_1)^4\right)\right)$</p>
<p>Can I use Gibbs sampling to sample from that? How can I get the full conditional distributions, and how can I draw samples from those conditional distributions whi... | 45,634 |
<p>Two independent random variables, X and Y, are uniformly distributed on the unit interval (-1,1).</p>
<p>Determine the density for U=min(X,Y) and for W=max(X,Y)</p> | 72,515 |
<p>The answer to this <a href="http://stats.stackexchange.com/questions/30643/confusion-regarding-kriging">question</a> gave me an interesting idea. The part that interested me was a brief description of kriging concluded by </p>
<blockquote>
<p>The way, kriging as usually practiced is not quite the same as
least ... | 72,516 |
<p>We have question regarding the analysis of panel data in R (<a href="http://cran.r-project.org/web/packages/plm/vignettes/plm.pdf" rel="nofollow">plm</a>) which was observed over two time scales. </p>
<p>As way of a background, we have completed an economic experiment with a group of 6-8 students, which is complete... | 72,517 |
<p>For polynomial fitting with a polynomial of degree $n$, we have $n$ degrees of freedom. Is there a similar concept for $k$ nearest neighbors? Is there any way to compare the degrees in general? I come from an EE background so I might not familiar with some of the advanced terminology.</p> | 72,518 |
<p>Is the loss sequence returned by cv.glmnet (the slot "cvm") on the standardized variable scale or the original scale? This only affects the penalty part of the loss, I think. In other words, are models obtained by calling cv.glmnet with standardize=TRUE comparable to those obtained with standardize=FALSE?</p> | 37,651 |
<p>I have a statistics interpretation question. I've recently performed a two-way anova to identify an interaction term between my categorical independent variables (genotype + temperature) that influences my continuous dependent variable (speed). My hypothesis is that genotype+temperature strongly interact to reduce ... | 45,641 |
<p>I have an issue with describing the results of a simple analysis in a self-consistent way.</p>
<p>This is for a study of an intervention that took place in 25 different towns, to reduce the number of cot deaths that took place. Data is for the number of cot deaths before the intervention started (the 'baseline' pha... | 72,519 |
<p>I'm dealing with two correlated random variables which are modeled via a bivariate normal distribution. I have values for the means ($\mu_x, \mu_y$) and individual variances ($\sigma_x, \sigma_y$) of the variables (effectively the marginalize normal distributions). Given new observations of the random variables, cou... | 45,644 |
<p>As far as I know first I have to standardize the variables. Then I have to check whether they are normal or not, then I should check whether there is multicolinearity. Then I perform the make regression and check whether the residuals are randomly distributed or not.</p>
<p>Is there anything I am missing or have wr... | 49,899 |
<p>Given multiple cross-validation folds of a logistic regression, and the resulting multiple estimates of each regression coefficient, how should one measure whether or not a predictor (or set of predictors) is/are stable and meaningful based on the regression coefficient(s)? Is this different for linear regression?</... | 308 |
<p>Correlation does not imply causation.
Causation does imply correlation but not necessarily linear correlation.
...
So does correlation imply high-order causation?
If A and B are correlated, is it always possible to find <code>K={K1 K2 ... Kn}</code> variables such that </p>
<pre><code>A~K1, K1~K2, ...,Kn-1~Kn and K... | 72,520 |
<p>I'm implementing a decision tree algorithm, and I'd like to get a feel for how it performs relative to other implementations. Can anyone recommend popular datasets for training and testing decision tree algorithms? I've found some resources like <a href="http://archive.ics.uci.edu/ml/datasets.html" rel="nofollow">th... | 72,521 |
<p>I am currently working on implementing <code>SVAR</code> model in an economic analysis. I have 10 variables in my analysis and currently struggling to incorporate the short run restrictions.</p>
<p>Here is an example with four variables say Y1 (GDP), Y2(Exchange rate), Y3 (interest rate) Y4(Bank risk). I wanted to ... | 3,096 |
<p>Is it reasonable to choose a regression model with a value of <code>0</code> for the intercept when this makes logical sense? For example, I am trying to model a physical geometric relationship, and I know that when <code>x = 0</code>, <code>y = 0</code>. Yet the consequences of choosing such a model are that the <c... | 19,716 |
<p>I'm new to <a href="http://stats.stackexchange" rel="nofollow">http://stats.stackexchange</a>, so please let me know if I'm doing something wrong.</p>
<p>I have the following problem:</p>
<p>Suppose that there is a car traveling along a flat surface. There are no roads on this surface, so the travel can be thought... | 37,770 |
<p>I just read about a procedure I'd never heard of, and was wondering if anyone has had any experience with it. In Donald Berry's "Statistics" book, he presents an alternative to doing a t-test by modifying the sample standard deviation, with a factor that increases with lower-N:</p>
<p>$s\rightarrow s\left(1+\frac{... | 72,522 |
<p>I'm stuck with this one.</p>
<p>Let $X_1,...X_n$ be an i.i.d. sequence of random variables with CDF F. The empirical CDF of $X_i$ is defined
$$
\hat F_n(x) = \frac{1}{n} \sum_{1 \leq i \leq n} I\{X_I \leq x \}.
$$
Note that for $x \in \Re$, $\hat F_n(x) \xrightarrow{p} F(x)$. Also, define the smallest median of P a... | 72,523 |
<p>I am very new about statistics. So, please understand if my question is somewhat awkward, and please give me related any advice. </p>
<p>I have some data set.</p>
<p>X = 500 x 100 (500 observations x 100 predictor variables)</p>
<p>Y = 500 x 1 (500 response variables)</p>
<p>With that data, I first estimated mea... | 72,524 |
<p>In an election, candidate $A$ receives $n$ votes and candidate $B$ receives $m$ votes where $n>m$. The probability that $A$ is always ahead in the count of the votes is $\dfrac{n-m}{n+m}$. This is known as <a href="http://en.wikipedia.org/wiki/Bertrand%27s_ballot_theorem" rel="nofollow">Bertrand's ballot theorem<... | 34,489 |
<p>I understand what is K-fold cross validation, but what does balanced folds mean? I thought k-fold cross validation is balanced. What are the differences between the two?</p> | 72,525 |
<p>A coin that comes up heads with probability $p$ is flipped $n$ consecutive times. What is the probability that starting with the first flip there are always more heads than tails that have appeared?</p>
<p>I have seen hints that this is <a href="http://en.wikipedia.org/wiki/Bertrand%27s_ballot_theorem" rel="nofollo... | 72,526 |
<p>Background: In some cognitive psychology research areas N-alternative forced choice tasks are common. The most common of these is a two alternative forced choice (2AFC). This usually takes the form of participants being given a stimulus and asked to make one of two judgement, e.g. the target stimuli is present/ab... | 72,527 |
<p>It seems like the current revision of lmer does not allow for custom link functions. </p>
<ol>
<li><p>If one needs to fit a logistic
linear mixed effect model with a
custom link function what options
are available in R?</p></li>
<li><p>If none - what options are available in other
statistics/programming packages?<... | 37,783 |
<p><img src="http://i.stack.imgur.com/CLm9y.jpg" alt="enter image description here"></p>
<p>How do I compute the Gini index using <strong>Instance</strong> attribute as attribute test condition? </p>
<p>I calculated the Gini, but I have no clue how to do it for this Instance attribute.</p>
<p>$$\text{Gini for } a_1 ... | 72,528 |
<p>Suppose I have data of the following form</p>
<pre><code>t1 = data.frame(a=c(2,3,3,1,5),b=c(6,4,5,2,1))
t2 = data.frame(a=c(3,4,4,1,8),b=c(5,5,5,3,3))
</code></pre>
<p>If you consider <code>plot(t1$a,t1$b)</code> and <code>plot(t2$a,t2$b)</code>, you can imagine that the second plot is produced by taking every poi... | 72,529 |
<p>Let a bag have 1000 balls, 100 red and 900 blue.
Now, let us get ten independent samples (without replacement within each sample) of the original population (10% each).
Proceed to count the number of red balls in each sample, i.e.:</p>
<pre><code>(9, 10, 10, 11, 13, 8, 5, 15, 12, 9)
</code></pre>
<p>To estimate th... | 34,494 |
<p>Conditions of a weak-stationary time series are: (1) constant in mean (2) constant in second-order moments.</p>
<p>We can test whether a time series is stationary using like <code>kpss.test()</code> in R. If say, a time series $X_t$ is non-stationary by the test. Is there a way to check whether it is not constant i... | 72,530 |
<p>Let a discrete Random Variable $T$ have CDF $F_T(T)$. Could you please help me understand why $$ P \left[ F_T (T) \leq a_1 \right] \leq a_1 $$</p>
<p>I know that the result holds with equality for the continuous case, it is known as Probability Integral Transform, but I am having trouble understanding it for the Di... | 72,531 |
<p>I was wondering if there's any good R libraries out there for deep learning neural networks? I know there's the <code>nnet</code>, <code>neuralnet</code>, and <code>RSNNS</code>, but none of these seem to implement deep learning methods.</p>
<p>I'm especially interested in unsupervised followed by supervised learn... | 72,532 |
<p>I am working with customer satisfaction data where the dependent variable is "Overall satisfaction" and the independent variables are satisfaction with various areas such as customer support, delivery etc.</p>
<p>I want to suggest areas where the company should focus on in order to improve overall satisfaction. </p... | 72,533 |
<p>Suppose we have trained a model (function, algorithm) $M$ which gives prediction to a new sample $x$ not observed in the training set, $M(x)$. It is natural to assume that the quality of prediction $M(x)$ depends on similarity of $x$ with the training set $X$. I wonder if there are any indices/methods which would ev... | 72,534 |
<p>I am new to g*power and have a question about which test I have to choose and how to interpret the given sample size.</p>
<p>I have 2 measurements (pre / post), one control-group and one intervention-group. In a reference study, I was able to find an effect size of .7 for the most important parameter. In g*power I ... | 34,497 |
<p>Do anyone know if in the field of topic modeling and latent class analysis, it exists some heuristic to determine a good number of latent classes?</p> | 49,900 |
<p>I'd like to calculate the statistical power of a likelihood ratio test based on mutual information.</p>
<p>I'm using the asymptotic property that the test statistic $G = 2NI$ where $N$ is the sample size and $I$ is the mutual information.</p>
<p>I have a large sample size (say $10^6$ observations) but also many d... | 37,672 |
<p>There's a question for <a href="http://stats.stackexchange.com/questions/4612/good-econometrics-textbooks">textbooks</a> here, but I would like to ask similar question about handbooks: What econometrics handbooks would you recommend?</p>
<p>Assumed audience is researchers and graduate-level students. It needs to in... | 72,535 |
<p>Let's say you have an overall group of financial institutions (fi) made of banks (ba) and federal credit unions (fcu). The total number of fi is 73. The number of ba is 46 and the number fcu is 27. Let's assume also the total numbers of employees working for ba is 2500 and the total numbers of employees working for ... | 34,504 |
<p>There are three random variables, $x,y,z$. The three correlations between the three variables are the same. That is,</p>
<p>$$\rho=\textrm{cor}(x,y)=\textrm{cor}(x,z)=\textrm{cor}(y,z)$$</p>
<p>What is the tightest bound you can give for $\rho$?</p> | 49,690 |
<p>I'm trying to find multiple break points by using <code>processStream</code> from <code>CPM</code> package on R.
Can someone enlighten me on what is <code>ARL0</code> how does one determine what <code>ARL0</code> should be used for?</p>
<pre><code>processStream(ret.fin.chn,"Kolmogorov-Smirnov",ARL0=500,lambda=NA)
$... | 72,536 |
<p>Here is a problem from a practice test. Suppose that $$X_i = \mu + \epsilon_i,\quad i=1,\ldots,n\quad \epsilon_i\sim N(0,\sigma^2_1)$$ $$Y_i = \mu + \delta_i,\quad i=1,\ldots,m\quad \delta_i\sim N(0,\sigma^2_2)$$ All $\epsilon_i$'s and $\delta_i$'s are independent. The paramters $\mu, \sigma_1^2, $ and $\sigma_2^2$ ... | 72,537 |
<p>I want to express the joint probability of $\Phi_A$ and $\Phi_B$: $p(\Phi_A, \Phi_B)$ conditioned that $\Phi_A$ and $\Phi_B$ are both greater than some value C. How would I express this mathematically? I guess my intuition says:</p>
<p>$p(\Phi_A, \Phi_B | \bf{\Phi} >C)$</p>
<p>Is this correct? Is there a bet... | 72,538 |
<p>If you could review and share any insights/guidance you may have to share, i would sincerely appreciate it!!!!!</p>
<p><strong>Dataset</strong> </p>
<p>Server id---------Repair id---------Repair Type---------Date of repair </p>
<ul>
<li>each server can have the same type of repair multiple times in its lifetime <... | 72,539 |
<p>I am wondering if one can relate the <a href="http://en.wikipedia.org/wiki/KL-divergence" rel="nofollow">KL divergence</a> to the probability of error in a Bayesian binary hypothesis testing setting. That is, we have to decide between hypotheses $A$ and $B$ given observationx, and we have prior probabilities of eit... | 72,540 |
<p>Suppose we have a data set of means and standard deviations. So the data are of the form $X_1=(\bar{x}_1, \bar{x}_2,\dots, \bar{x}_n)$ and $X_2 =(s_1,s_2, \dots, s_n)$. Is there any utility in looking at $\overline{X_1}$? Also is there a relationship between $\text{Stdev}(X_1)$ and $X_2$? It seems that $X_2$ gives i... | 72,541 |
<p>I am looking for suggestions on how to deal with uneven time points and missing data in a single-group repeated-measures design.</p>
<p><b>BACKGROUND:</b> A group of 220 subjects went through a 4-month weight loss treatment, and were given wireless scales to weigh themselves daily at home. The primary outcome is ch... | 47,280 |
<p>I have a homework problem about finding an optimal decision boundary. I know the formula (not really the process) for calculating one, so that may be another question entirely, but I do know I need the mean, covariance, and priors. The question is shown below</p>
<pre><code>Suppose points in R^2 are being obtained ... | 72,542 |
<p>I have very basic knowledge of stats so my question may sound very simplistic. I have a large time series of measured data and have calibrated a model with five parameters to make predictions. I would like to test the sensitivity of my model but I am not sure what statistical method to use. I've been reading about s... | 47,306 |
<p>I'd like to create a composite item from variables with the following scale: strongly disagree, disagree, neither agree or disagree, agree, strongly agree and don't know. </p>
<p>I was going to code the scale as 1=strongly disagree, 5=strongly agree, and calculate the composite item with these values. However I don... | 72,543 |
<p>So say I am testing the predictive value of a predictor towards a "DV" within a survey data-set, between two time-points. Say also that I have measurements of both variables at all time points and that I can see that the DV and the predictor correlate at baseline. If I use linear regression or pearson correlation to... | 34,510 |
<p>I am trying to make a prediction in a time series with window 512 and horizon 2. I want to know if it's worth using ARIMA, that seems to be hard to understand, instead of the simple Autoregressive model?</p> | 72,544 |
<p>How do I interpret the following output from R for a two-way repeated measures ANOVA</p>
<pre><code>Model <- aov(value ~ BWRatio * NumGraBoolean + Error(participant/(BWRatio * NumGraBoolean)))
</code></pre>
<p><img src="http://i.stack.imgur.com/kQCo7.png" alt="enter image description here"></p>
<p>In particula... | 72,545 |
<p>Suppose that we have the following model
$$
y[t] = A_1\sin(\omega_1 t+\phi_1)+A_2\sin(\omega_2 t + \phi_2)+ \cdots + A_p \sin(\omega_pt + \phi_p) + z(t) .
$$
Let us call this signal as B.
Then in matlab I executed the following commands</p>
<pre><code>>> [pxxr,fr]=pyulear(B,50,1024,100);
>> plot(fr,px... | 34,512 |
<p>I want to cluster time-series concerning sales of products. In the database I have 26weeks after launching each products and units sold each week.</p>
<p>One of the method of clustering is to cluster parameters of growth curve fitted to time-series. </p>
<p>Can somebody tell me what should I do before fitting logi... | 72,546 |
<p>I'm new to the site, and to Bayesian statistics and was hoping to get some help.</p>
<p>I'm currently working through some study exercises and am required to compute the mean and variance of the posterior density in R. The prior density is represented by a normal curve with a mean of 6 and variance of .25, whereas... | 72,547 |
<p>I have a dependent variable <code>C</code> and an independent variable <code>VPT</code>.
<code>VPT</code> is the average volume per tree (in cubic foot) of a timber stand. <code>C</code> ist costs resulting from a <a href="https://github.com/ustroetz/MT/blob/master/CostFunc.py" rel="nofollow">cost function</a>, that... | 34,514 |
<p>Are there any packages that implement the Autoclass/ Naive Bayes Clustering algorithm in R or Python? </p>
<p>Alternatively, what are some other clustering algorithms that can handle both categorical and numeric variables that are implemented in either R or Python?</p> | 34,515 |
<p>I have two data sets to compare. Each is a list of billed amounts by diagnosis codes. The data differs in that the diagnosis codes may be different for some of the billed amounts. There are approximately 32 different diagnosis codes that were used. What type of statistical analysis is most appropriate in compari... | 72,548 |
<p>I have just read up on Bouchard's Minnesota Twins study that turned up some amazing identical similarities in the lives of some identical twins reared apart. Both had same jobs, married and divorced women of same name, named dogs and children same etc. I'm not sure what percentage of their study group had these iden... | 72,549 |
<p>I'm using <code>patternnet</code> for my binary classification in <code>MATLAB</code> and using <code>10-fold cross validation</code>. I'm repeating my neural network in a loop for some times to see the results. when i see neural network training window in <code>MATLAB</code> after 15~40 iterations the neural networ... | 34,517 |
<p>What is the difference between the classic meta-analysis (that aggregates effect sizes from a sample of studies to a summary effect size), meta-regression analysis and moderator analysis?</p>
<p>As I understood moderator analysis is used to explain heterogeneity in a meta-analysis by regressing a vector containing ... | 34,518 |
<p>Let $X_i, i \geq 1,$ be independent uniform (0, 1) random variables, and define $N$ by $$N=\min\{n:X_n < X_{n-1}\}$$. I need to prove that $$P\{N \geq k | X_0=x\} = \frac{(1-x)^{k-1}}{(k-1)!}$$. I am stuck when finding the quantities like $P(X_i \geq X_{i-1} | X_{j} \geq X_{j-1}, \forall j\lt i)$. I have also pos... | 45,680 |
<p>I thought I might toy with some Bayesian variable selection, following a <a href="http://darrenjw.wordpress.com/2012/11/20/getting-started-with-bayesian-variable-selection-using-jags-and-rjags/">nice blog post</a> and the linked papers therein. I wrote a <a href="http://www.mediafire.com/?1c8g8tcm55m4uw4">program</... | 72,550 |
<p>I have a very sparse set of measurements of a quantity, around 10 measurements at different locations across a continent. The distributions of locations is highly irregular. I would like to smooth these into values on a regularly spaced grid over the continent.</p>
<p>We actually have a much denser set of observati... | 34,521 |
<p>For my linear regression class we need to come up with some kind of simple experiment (we must collect the data, can't get it online) for which we can use the methods we have studied in class (simple linear regression, multiple linear regression, ANOVA, ...) to analyze the data. </p>
<p>I am having the hardest time... | 34,523 |
<p>I use the machine learning software <code>WEKA</code> for data mining on biological data. I would describe my dataset as unbalanced: It comprises around 2000 instances, splitting in classes of 900, 500, 350, 160 that are very important to have in the dataset and some less important smaller classes that are nice to h... | 72,551 |
<p>I'm trying to simulate this scenario: 10 different algorithms are solving a number of problems. All 10 are run on each problem instance, which means if a particular problem instance is hard, I expect all algorithms to perform quite bad and vice versa. </p>
<p>Now, to simulate this, I created 10 different normal dis... | 34,530 |
<p>How do I sample from a distribution that is the product of a gaussian and an inverse-wishart distribution? I was going to use <a href="http://en.wikipedia.org/wiki/Inverse_transform_sampling" rel="nofollow">inverse transform sampling</a> but a friend said that he thinks there is a much simpler way of doing it, a tri... | 34,531 |
<p>In my free time, I am working on a small web based system which collects crash reports (but not other, non-crashing bug reports) that are sent from Delphi Windows applications.</p>
<p>For troubleshooting, users would love to have a data-mining feature to find relationships between hardware or operating system versi... | 72,552 |
<p>I have gathered information on the rate increases allowed by a government regulator over about 17 years. As background, utilities in this area must apply to the regulator if they wish to raise their rates, in exchange for being granted a quasi-monopoly in the market.</p>
<p>In this period, there are 65 'usable' de... | 72,553 |
<p><a href="http://en.wikipedia.org/wiki/Resampling_%28statistics%29#Permutation_tests" rel="nofollow">Permutation tests</a> can be used to test the likelihood of obtaining a single mean value (composed of the average of k-fold CV) classifier accuracy by chance, such as for a linear classifier using two classes. The pe... | 72,554 |
<p>Even if the $F$ statistic in an ANOVA test is significant, we may need to do further testing before drawing conclusions. The most common method for doing this involves the use of a multiple comparisons procedure. I am trying to understand why Tukey's method is used over the two-sample $t$-test. I read the following ... | 34,534 |
<p>I want to perform a very simple linear regression in <code>R</code>. The formula is as simple as $y = ax + b$. However I would like the slope ($a$) to be inside an interval, let's say, between 1.4 and 1.6.</p>
<p>How can this be done?</p> | 49,772 |
<p>
Different textbooks cite different conditions for the existence of a Fisher information matrix. Several such conditions are listed below, each of which appears in some, but not all, of the definitions of "Fisher information matrix".
<ol>
<li>
Is there a standard, minimal set of conditions?
</li>
<li>
Of the 5 con... | 72,555 |
<p>For $i=1, \ldots, K$ and $j=1, \ldots,n$, assume the following model.
\begin{align}
X_{ij} \mid \mu_i, \sigma^2 & \stackrel{_\text{iid}}{\sim} N(\mu_i, \sigma^2) \nonumber \\
\mu_i & \stackrel{_\text{iid}}{\sim} N(\mu, \tau^2) \nonumber \\
\ln(\sigma^2) & \sim N(\mu_v, \tau_v^2)
\end{align}
First assum... | 72,556 |
<p>I know table can count contingency table, what if I want to summarize all elements that fall in a cell of the table using some type of function, such as mean?</p>
<p>For example</p>
<pre><code>facA = rep(1:3, 4)
facB = rep(c(rep(1, 3), rep(2, 3)), 2)
value = rnorm(12)
</code></pre>
<p>How do I summarize the mea... | 45,697 |
<p>I'm kinda brand new to statistics and I'm developing classification algorythm. My method is based on simple chi-square goodness of fit. I am counting the effect size of known cases to predict the future ones.</p>
<p>My problem is that I don't really know how to deal with large sample sizes, neither do I know when i... | 72,557 |
<p>I want to be able to compare the angles of neighbours in a herd of hippos. I have data for the x and y coordinates and the angles that they are facing (using <a href="http://rsbweb.nih.gov/ij/" rel="nofollow">imageJ</a>, angles are between -180 and 180 with 0 being a horizontal straight line across the middle of the... | 72,558 |
<p>Say I have $N$ items that are partitioned / clustered and I want to randomly repartition these items, such that the distribution of sizes of the clusters is 'similar' to those that I already have. I'm viewing this (perhaps unhelpfully), as trying to sample $k$ natural numbers, such that $x_i \geq 1$ and $\sum_{i=1}^... | 39,135 |
<p>Let $X_{i}, i\ge 1$, be i.i.d. random variables defined on a probability space $(\Omega, \mathcal F,P)$ such that $P(X_{i}=1)=P(X_{i}=-1)=\frac{1}{2}$. Consider the filtration $\mathcal F_{n}=\sigma(X_{1},\dots,X_{n})$ on this space and the random walk $R_{i}=\sum_{i=1}^{n} X_{i}$. </p>
<p>Show that $R_{n}^{2}-n$ ... | 72,559 |
<p>I understand that clustering is meant to group items together, is there any ways that we can quantify saying Cluster A is more important than Cluster B? Other than counting the number of items in a cluster?</p> | 72,560 |
<p>I'm looking for implementation of <strong>self organizing map</strong> which for the clustering part <strong>uses spectral clustering rather than k-means</strong>. </p>
<p>Does anyone knows something about it ?</p> | 34,541 |
<p>I am trying to write a function in R that determines which of the following statistical tests should be run on a set of data:</p>
<p>{paired-t, sign, two-sample t, pooled two-sample t, two proportions, F}</p>
<p>-Data sets have two columns, representing the X and Y values.</p>
<p>-The focus of the test on the dat... | 72,561 |
<p>I have three groups. Both have small sample sizes (<10). And we can't check the assumption of normality. I want to compare any two of them.</p>
<p>What to do in this case( unequal small sizes, non-normality)</p> | 72,562 |
<p>I've read through some past posts about using the KS test when the distribution parameters are estimated. <a href="http://stats.stackexchange.com/questions/45033/can-i-use-kolmogorov-smirnov-test-and-estimate-distribution-parameters">This one</a> in particular was very helpful, and I implemented Greg Snow's suggesti... | 34,544 |
<pre><code>data a;
input treat$ rep boreria mimiosa asysta axono seleria paspa macran melas scopo cleom otto;
cards;
M 1 0.20 0.00 0.00 0.00 0.00 12.20 0.00 0.00 0.00 4.90 0.00
M 2 0.00 0.00 0.00 0.64 0.00 0.00 0.00 0.00 0.00 0.00 0.00
M ... | 20,026 |
<p>I have 2x2 design with n = 3 (averages) for each group (<a href="http://stackoverflow.com/questions/10330314/pointrange-plot-with-boxplot-type-grouping">see here</a>). I am not sure that my data follows any particular distribution, but I would like to use confidence intervals as error bars in a dot plot. Thus I can'... | 34,548 |
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