question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p><img src="http://i.stack.imgur.com/IBHdy.png" alt="enter image description here"></p>
<p>This is an excerpt from "Modern mathematical statistics with applications" by Devore et al.
What puzzles me is that the estimator cannot help being dependent on $\theta$, since the sample depends on the parameter.</p> | 73,384 |
<p>I have a mixed model built using Data A below, and now I want to validate the model using Data B. What should I do to actually "validate" the model?</p>
<pre><code>model <- lme(Y~1+X1+X3, random=~1|School, method="ML", data=A)
</code></pre>
<p>I know how to use "predict(model,B) - B$Y" to get residuals, but wha... | 35,718 |
<p>I have some project categories $(PC_1, ... ,PC_n)$ and some institutions $(I_1, ..., I_n)$ and would like to determine how fairly projects are assigned to institutions and their project categories by some external sources.</p>
<p>I was thinking about using some chi square based measure for this. Basically I have a ... | 35,719 |
<p>I'm playing with support vector machines (SVM) using the e1071::svm() function in R, and I encountered a scenario where I asked it for a leave-one-out cross-validated classification of a 2-category response and obtained a total accuracy of 38% (35/90), which, given 90 samples, ends up with a 95% confidence interval ... | 35,721 |
<p>I am trying to compare 2 ideas to see which one is better/more effective - I am looking to see if a significant difference. (2 conditions)</p>
<p>We used a questionnaire to gather feedback from hundreds of people.
(Questions include: how likely would you buy it, how likely would you tell your friends and family, I ... | 73,385 |
<p>When you are trying to fit models to a large dataset, the common advice is to partition the data into three parts: the training, validation, and test dataset.</p>
<p>This is because the models usually have three "levels" of parameters: the first "parameter" is the model class (e.g. SVM, neural network, random fores... | 73,386 |
<p>I was thinking of this problem.</p>
<p><a href="http://en.wikipedia.org/wiki/Two_envelopes_problem" rel="nofollow">http://en.wikipedia.org/wiki/Two_envelopes_problem</a></p>
<p>I believe the solution and I think I understand it, but if I take the following approach I'm completely confused.</p>
<p>Problem 1:</p>
... | 73,387 |
<p>We are measuring data with a high sample rate (20 kHz) and calculated a big standard error due to our system setup. Currently we are only interested in slow signals (in the order of Hz's) is it valid to use averaging (once per 20.000 samples) and thus lower our standard error with an order 20.000?</p> | 41,569 |
<p>I have four numeric variables. All of them are measures of soil quality. Higher the variable, higher the quality. The range for all of them is different:</p>
<p>Var1 from 1 to 10</p>
<p>Var2 from 1000 to 2000</p>
<p>Var3 from 150 to 300</p>
<p>Var4 from 0 to 5</p>
<p>I need to combine four variables into single... | 49,470 |
<p><strong>INTRO</strong></p>
<p>I have trained a SVM model based on 300 training cases in order to build a filter that should help me extract a bigger and evenly balanced training set, that is to be validated by human judges.</p>
<p><strong>DATA</strong></p>
<p>My training set is:</p>
<pre><code>288 negative cases... | 47,744 |
<p>I am doing cross-validation using the leave-one-out cross-validation method (total 10 runs). I have predicted $\hat{y}$ and observed $y$ from all the runs. I have applied the following equation to calculate $R^2$. Can anyone please confirm whether I am doing right? I am confused because the $R^2$ value appeared nega... | 27,748 |
<p>I understand supervised and unsupervised learning well, and would be able to identify some 'basic' examples of, for example, supervised classifcation as:</p>
<ul>
<li>SVMs</li>
<li>Random Forests</li>
<li>Logistic Regression</li>
</ul>
<p>These are key works in the field which have lots of code and publications a... | 35,729 |
<p>I have a data table T1, that contains nearly a thousand variables (V1) and around 200 million data points. The data is sparse and most of the entries are NA. Each datapoints have a unique id and date pair to distinguish from another.</p>
<p>I have another table T2, which contains a separate set of variables (V2). T... | 73,388 |
<p>There are several packages that can apply the Durbin-Watson test for serial correlation. However, I do not see a package that supports the calculation in the case that once has a GLS weighted regression.</p>
<p>For example, CRAN package <a href="http://cran.r-project.org/web/packages/lmtest/index.html" rel="nofollo... | 1,008 |
<p>I have <strong>6</strong> masses as input data which they are expressed as m+/- delta m.
Via a complicated processes I calculate <strong>decay width</strong> as a final result.
It takes a long time for the code to compute decay width for example for <strong>m</strong> values. Let's call it <strong>(decay width)_cent... | 35,730 |
<p>Given a data matrix like this:</p>
<pre><code> [,1] [,2] [,3] [,4] [,5] [,6] [,7]
[1,] 9.520 11.137 16.576 18.225 20.576 25.861 NA
[2,] 9.005 9.491 11.106 16.530 18.184 20.495 25.773
[3,] 9.437 11.050 20.393 25.711 NA NA NA
[4,] 9.442 11.058 20.411 25.711 NA NA ... | 73,389 |
<p>I am trying to fit a model investigating the amount of the loan (or a transformation of it) as a function of the the variables <code>income</code>, <code>gender</code>, <code>customer</code> and <code>age</code>.</p>
<p>Fitting a standard linear regression gives poor results (R-squared of only 0.27). Besides, the r... | 73,390 |
<p>I am an anthropology student. I am researching the inter-relatedness of most if not all humans as part of my studies. I personally have an interest in statistics and probability theory and I have used it in regards to this topic. Before I explain my theory, I received the following from a computer scientist that I w... | 73,391 |
<p>I trained a few different models, (Perceptron, Stochastic Gradient Descent and Naive Bayes), each with different parameters. I then scored their accuracy on a cross validation set.</p>
<p>The scores on the best parameter Perceptron, SGD and NB models were 93%, 91% and 94% respectively. </p>
<p>I didn't expect such... | 35,733 |
<p>This is in reference to the <a href="http://en.wikipedia.org/wiki/Girsanov_theorem" rel="nofollow">Girsanov theorem</a> however question is general. If $X$ is a standard normal variable $N(0,1)$, why is expectation of $e^{-\mu X - \mu^2/2}$ equal to 1?</p>
<p>Shouldn't it be $e^{-\mu^2/2}$?</p> | 47,133 |
<p>I have data on commute times over a specified route over different days during different conditions. Some of the conditions are categorical (e.g., weather, traffic), and some of them are numeric (e.g., time departing from origin). I'd like to find out which of these conditions most strongly correlate with the shorte... | 73,392 |
<p>I would like to compare two linear regression models which represent degradation rates of a mRNA over time under two different conditions. The data for each model collected independently. </p>
<p>Here is the dataset.</p>
<pre>
Time (hours) log(Treatment A) log(treatment B)
0 2.02 1.97
0 2.04 2.06
... | 37,528 |
<p>I am confused between what types of problems these three models capture, and their applications:</p>
<ul>
<li><a href="http://en.wikipedia.org/wiki/Latent_Dirichlet_allocation" rel="nofollow">Latent Dirichlet Allocation (LDA)</a></li>
<li><a href="http://en.wikipedia.org/wiki/Dirichlet_process" rel="nofollow">Diric... | 73,393 |
<p>I have been trying to use <a href="http://cran.r-project.org/web/packages/sspir/index.html" rel="nofollow">sspir</a> R package to estimate the following Poisson model:</p>
<p>$Y_{t}\sim Po(\exp(\lambda_{t}));$ such that $\lambda_{t}=X_{t}\beta
+\gamma_{t}$ and $\gamma_{t}=\theta\gamma_{t-1}+u_{t},u_{t}\sim NID(0,\s... | 35,735 |
<p>I'm trying to plot forecast and real data on the same plot. But there is always gap between them on the image :</p>
<p><img src="http://i.stack.imgur.com/ni7FR.png" alt="enter image description here"></p>
<p>I use for the forecasting following code:
y=boardings[,1]
## Simple Exponential smoothing
#pred... | 73,394 |
<p>Assume the model $ \ y = X\beta + u \ $ with $\ W \ $ is a $ \ n\times l \ $ so called matrix of instruments. </p>
<p>The following assumptions hold. There is a law of large numbers (LLN) for 1.,2.,3. and 4. such that</p>
<ol>
<li><p>$\text{plim}_{n\to\infty} \ \left(\frac{X^TX}{n}\right) = m_{X^TX}$</p>
<p>holds... | 73,395 |
<p>From what I read the <a href="http://en.wikipedia.org/wiki/Theil%E2%80%93Sen_estimator" rel="nofollow">Theil-Sen estimator</a> seems to be a really cool estimator; robust and easy to understand. <strong>Would it be possible to device (or does it already exists) a Bayesian "version" of the Theil-Sen estimator so that... | 73,396 |
<p>I've been using a Metropolis/Gibbs sampler combination to generate a joint density for some parameters(it is a hierarchical model, with $y_i\sim Poisson(\lambda_i)$, $\lambda_i\sim Gamma(\alpha,\beta)$). What techniques can I use to lower autocorrelation(it is present in $\alpha$ and $\beta$)? I have been using thi... | 47,141 |
<p>I'm familiar with very basic plotting in R, but I'm not sure how best to create the reasonably-complicated plot described below.</p>
<p>I have developed a density estimation method that essentially fits an empirical distribution to multiple univariate samples, under distinct conditions. To be clear, let $\mathbf{x}... | 31,078 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/26970/validation-techniques-for-hierarchical-model">Validation techniques for hierarchical model</a> </p>
</blockquote>
<p>I already posted <a href="http://math.stackexchange.com/questions/135641/validatio... | 49,336 |
<p>I've been searching for a way to combine two hazard ratios from the same study for a meta-analysis, but found nothing. Does anyone know how to do this?</p>
<p>Any thoughts would be great.</p>
<p>Good Day,</p>
<p>Simon</p> | 73,397 |
<p>I have spent a fair amount of time trying to solve this problem but I can't find the solution. More specifically, I have the following matrix:</p>
<pre><code>P(D|E&F) = [ 0.5 0.3 0.5 0.2 ;
0.5 0.7 0.5 0.8 ]
</code></pre>
<p>All the variables are binary (two states)
D, E and F are nodes of a Bayes... | 35,743 |
<p>I used the MATLAB interface of libsvm for doing binary classification of 997-dimensional training data. I am trying to understand how the resulting model is used to compute the predicted output (which we get by calling <code>svmpredict</code>)</p>
<p>The model contains fields (it has linear kernel):</p>
<pre><code... | 73,398 |
<p>How can I measure separability between different number of instance of one feature vector? For example the main vector is <code>V=[1 1 2 3 4 5 7 8 10 100 1000 99 999 54]</code> and three sub-vector with different sample lengths are <code>t1=[1 1 2 3 99 1000]</code> or <code>t2=[1 10 1000]</code> or <code>t3=[2 3 4 1... | 73,399 |
<p>What are the most significant annual conferences focusing on quantitative methods in psychology?</p>
<p>This could include but is not limited to psychometrics, mathematical psychology, and statistical methods in psychology.</p>
<p>Rules:</p>
<ul>
<li>One conference per answer</li>
<li>Include a link to the confer... | 35,748 |
<p>I have two samples, one with $n_1 = 41,000$ and the other with $n_2 = 881$; the larger sample has a standard deviation of $13.74$, and the smaller has an $SD=10.75$. The means are different, and when I run a Welch's t-test, I get a $p < .001$. I'm not sure if that's the appropriate test. I checked the skew for bo... | 73,400 |
<p>This may be a stupid question but... is there a specific name for normalizing some data so that it has mean=0 and sd=1? </p>
<p>Or do I just say "data was normalized to have mean=0 and sd=1"?</p>
<p>thanks
nico</p> | 47,158 |
<p>Lately, I have been interested in phenomenons related to omission of variables. For example, it can be shown that the expected value of the sample variance under the inclusion of one variable $x_1$ but omission of one variable $x_2$ is $\mathbb{E}(s^2|x_1,x_2)= \sigma^2 + \frac{\sigma^2}{n-1} RSS_{x_1, \beta_2 x_2}$... | 35,751 |
<p>Am I correct to understand that the order in which variables are specified in a multifactorial ANOVA makes a difference but that the order does not matter when doing a multiple linear regression?</p>
<p>So assuming an outcome such as <strong>measured blood loss, y</strong> and two categorical variables</p>
<ol>
<l... | 47,159 |
<p>I have numerous road segments that belong to a city. Each road segment as a weight that is given to it due to its level of 'connectivity' (‘impact’from a small side street to a motorway). So, small neighbourhood road networks won’t have much weight at the regional level. These are calculated at different radii from ... | 73,401 |
<p>I have two bacterial markers, I'll just call them <em>X</em> and <em>Y</em>. <em>X</em> codes for virulence, whereas <em>Y</em> just indicates the bacteria is present. Consequently, <em>X</em> will not show up without <em>Y</em> although not all bacteria have <em>X</em>. Both also have a detection limit, although I ... | 73,402 |
<p>I perform prequential evaluation like this: start with a training set, classify a number of examples, then add the correctly classified examples in the training set and continue to classifying the next number of unseen examples. Is this supposed to increase performance as examples are added to the training set or th... | 73,403 |
<p>I have a set of observations. When I do an OLS I get a $\beta$. After I remove some values I also get a $\beta$. Now I want to test if the properties of two betas are the same? Please give me a hint how to do that?</p> | 35,760 |
<p>I am looking at the spatial patterns of turnover in aquatic assemblages using gradient forest and generalized dissimilarity models in R. I have species and environmental data for more than 400 sites sampled from streams across the country. However, I also have many missing values in my predictor (environmental) vari... | 35,761 |
<p>I'm writing a proposal for a restrospective cohort study using registry data. Am I right to think of the registry data as the whole population?</p>
<p>If it is the population, then am I right in thinking there is no need to calculate required sample size (as is required for other cohort studies) or confidence inter... | 73,404 |
<p>What is meant by subscripting the expectation with some distribution, e.g. $\mathrm{E_{f}}[h(X)]$? </p>
<p>If it's any help, here's the context:</p>
<p>In M.C. Simulation, we wanted </p>
<blockquote>
<p>$\mathrm{E[h(X)] = \int{h(x)f(x)dx}}$ </p>
</blockquote>
<p>so we used the law of large numbers and central... | 73,405 |
<p>I have a dataset that is clearly increasing as time goes on (exchange rate of a currency, monthly data over 20 years), my question is: Can I detrend the data and then difference it also to make it stationary, if the detrending in itself doesn't achieve this? And if so, would this be considered twice differenced, or ... | 35,763 |
<p>This is similar to question <a href="http://stats.stackexchange.com/questions/17602/caret-re-sampling-methods">Caret re-sampling methods</a>, although that really never answered this part of the question in an agreed upon way.</p>
<p>caret's train function offers <code>cv</code> and <code>repeatedcv</code>. What i... | 73,406 |
<p>The biological data is listed as following: </p>
<pre><code> V1 V2 V3 V4 V5 V6
0.064 0.014 0.016 0.012 0.013 0.023
0.056 0.000 0.000 0.008 0.010 0.000
0.042 0.014 0.024 0.008 0.017 0.023
0.031 0.014 0.016 0.008 0.013 0.023
0.068 0.000 0.008 0.004 0.020 0.000
0.081 0.000 0.000 0.004 0.010 0.000
0.06... | 73,407 |
<p>Dear all,
I was encouraged to ask this question here as well as on stackoverflow and would be very appreciative of any answers...</p>
<p>Due to hetereoscedasticity I'm doing bootstrapped linear regression (appeals more to me than robust regression). I'd like to create a plot along the lines of what I've done in th... | 47,164 |
<p>I conducted a multilevel analysis using repeated measures across four time points. The model contains intercept, linear slope and quadratic slope. I am interested in examining the extent to which variable A interacts with other identified variables in my model, so I added the interaction terms to intercept, linear s... | 73,408 |
<p>I am trying to apply a GLM in R. I have a binary response (success vs failure), and 3 categorical explanatory variables : Sex (male or female), Food (present or absent) and Wind (none, low, high). I arranged my data to end up with a count of number of success for each possible combination of explanatory variables. (... | 73,409 |
<p>$\chi^n_k=\sum_{i=1}^kx_i^n$ where $x_i$ are Gaussian variables and $n>2$?</p> | 35,766 |
<p>I have a question regarding a small investigation that I have been conducting into the relationship between the length of observation sequence, T, on which two decoders (BCJR and classic Viterbi) decode in a fixed small (2 state, 3 symbol) HMM.</p>
<p>When I plot $T$ against the average decoding rate accuracy, I ge... | 73,410 |
<p>Does anyone know of research which investigates the effectiveness (understandability?) of different visualization techniques? </p>
<p>For example, how quickly do people understand one form of visualization over another? Does interactivity with the visualization help people recall the data? Anything along those line... | 47,168 |
<p>This is a soft question: How can the order of a sample univariate data be reversed while preserving the variance?</p> | 35,767 |
<p>Hello I'm running anova with R and I am wondering what the differce is between multiway anova and single anova. I know single anova gives a different answer than multiway anova but I dont know how to quantify multiway anova.
Could someone explain in words the difference between:</p>
<ul>
<li>base~col1</li>
<li>base... | 73,411 |
<p>I am using random forests for a class.</p>
<p>I am predicting weight training.</p>
<p>In scikit learn I always used a rule of thumb of a depth of 5, the depth x features rounded.</p>
<p>I had 53 features, rounded to 50 x 5 and got 250 for number of trees.</p>
<p>I picked 250 trees and 5 node depth and got great ... | 27,350 |
<p>I want to make a 4 question, multiple choice survey in which each question asks about an analogous range of actions for slightly different scenarios. Each participant would only be administered the survey once. For example: </p>
<p>"In situation W how would you behave? (5[very aggressively] -- 1 [not aggressivel... | 73,412 |
<p>Please help! </p>
<p>I have developed a logistic regression model for prediction of a binary outcome at a range of different times following a set point. This gave me different models with different variables lists, although many variables overlapped and were seen to be significant at different times. I've then cre... | 35,771 |
<p>I posted this to mathoverflow and no one's answering:</p>
<p><a href="http://en.wikipedia.org/wiki/Scheff%C3%A9%27s_method">Scheffé's method</a> for identifying statistically significant contrasts is widely known. A <b>contrast</b> among the means $\mu_i$, $i=1,\ldots,r$ of $r$ populations is a linear combination ... | 73,413 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/12386/machine-learning-cookbook-reference-card-cheatsheet">Machine learning cookbook / reference card / cheatsheet?</a> </p>
</blockquote>
<p>I wonder if there is a good self-learning textbook for machine ... | 49,363 |
<p>I have a database of users with a field of the last time they logged in. Would this kind of data be considered "censored", and if so is there anything I can do with it beyond a histogram/density of how many people logged in within the last month, two months, etc? (To be clear: I only know the last time they logged i... | 35,775 |
<p>I have logs for users and posts in a blog platform for 3 years. I can easily find out how many posts each user have made per day/month/year/etc.</p>
<p>What I want to find out is if the frequency of posts is growing or not, in other words, if the users are contributing more over time or not. New users could join at... | 35,977 |
<p>What is the purpose of the link function as a component of the generalized linear model? Why do we need it?</p>
<p>Wikipedia states:</p>
<blockquote>
<p>It can be convenient to match the domain of the link function to the range of the distribution function's mean</p>
</blockquote>
<p>What's the advantage of doi... | 73,414 |
<p>I am interested in finding a leading indicator of $Y_t$. Is it sufficient to find a variable $X$ for which its lagged value is correlated with $Y$? Do I have to give consideration to the spurious regression phenomenon? Or is it correct to say that when it comes to forecasting, I can ignore this problem?</p> | 35,777 |
<p>Suppose you have $n$ players play a round robin tournament. A win adds 1 to the winning score of a player while a loss adds nothing. After the round robin tournament is finished the players are assigned ranks based on their scores, with ties being broken at random, the top player receiving a rank of $n-1$ and the bo... | 73,415 |
<p>Consider a set of observations $ \{ y_i \}$ and assume a Gaussian model for these data: $y_i \sim \mathcal{N}(\mu, \sigma^2)$. Suppose the mean parameter $\mu$ is known, but the variance parameter $\sigma^2$ is not. The conjugate prior for $\sigma^2$ is then the scaled inverse chi-squared distribution; consequently,... | 73,416 |
<p>I am working on monthly seasonally adjusted data. To the best of my knowledge (maybe I'm wrong), data is seasonally adjusted to take out any form of seasonality. </p>
<p>After doing an ACF of the second difference of my data with R, I saw a spike from the lag one point that crosses the horizontal dashed line. This ... | 73,417 |
<p>I am working on a data set. After using some model identification techniques, I came out with an ARIMA(0,2,1) model. </p>
<p>I used the <code>detectIO</code> function in the package <code>TSA</code> in R to detect an <em>innovative</em> outlier (IO) at the 48th observation of my original data set. </p>
<p>How do I... | 73,418 |
<p>I am using Logistic Regression in a <code>low event rate</code> situation.<br>
Overall universe: 46,000<br>
Events: 420</p>
<p>Conventional logistic regression models divide the data into training and test sets and compute the error rates. The final coefficients and threshold levels are chosen and a model is creat... | 73,419 |
<p>I'm working on a software and need to do some statistics. In my case I'm comparing two different networks that have a certain number of nodes with attributes and want to test with a Fisher's exact test if some of these attributes are enriched in the smaller one.<br>
I also have a good math library that is able to ca... | 35,782 |
<p>Why are measures of dispersion calculated relative to some central point? Why wouldn't, for instance, all possible non-repeated, pairwise differences in the dataset be a valid measure of spread?</p> | 35,784 |
<p>I am new to statistics and within the last two days I tried to get my head around PCA plots. Now, I kind of understand what they are showing but I am still not sure about the 95% confidence ellipse that is very often shown in such plots. The 2 dimensional PCA plot displays the two biggest variances (whatever these a... | 73,420 |
<p>I am building a scoring model for rating an individual on trustworthiness. The parameters of the model are not fixed and I have no historical data to test. So to test the validity of the parameters and their weightings, I have built random samples using Monte Carlo simulation. I have now came across the term predict... | 73,421 |
<p>I was studying Deep Belief Network (DBN) and have questions. </p>
<p>1) According to the definition of DBN, DBN is formed by stacking RBM on top of each other such that the hidden layer in a lower layer becomes the input layer in the above layer. However, when I read the papers by Geoff Hinton (for example, "a fast... | 451 |
<p>Is there a standard hypothesis test for differences in the mean of a continuous dependent variable with respect to a single ordered categorical variable. </p>
<p>By specifying that the independent variable is ordered, I also mean to impose the assumption that the dependent variable is monotonic in the independent ... | 14,632 |
<p>Last week I had an interesting discussion with a good friend of mine. He had been playing some <a href="http://en.wikipedia.org/wiki/Online_poker">online poker</a> and suggested that there is a relationship between new subscription/additional money transfer and the cards that you're dealt, i.e. you get good cards to... | 73,422 |
<p>For a linear regression fit for a problem with p variables X_i ranging between 0 and 1, where p>20 (I don't know if that is relevant or not), and the number of samples is about 1000, I wanted to estimate the variance contribution for each of the variables using the regression coefficients. If I understood correctly ... | 35,792 |
<p>The <code>chisq.test</code> function in R includes a <code>y =</code> argument, which is to <code>NULL</code> by default. The help page doesn't explain what this argument does, and playing round with numbers doesn't give any clues, for example all these give exactly same results:</p>
<pre><code>chisq.test(x=c(20, 1... | 18,145 |
<p>The dependent variable of my problem is highly concentrated around zero. Here is a stemplot</p>
<pre><code> The decimal point is 6 digit(s) to the right of the |
-2 | 511
-1 | 92221
-0 | 87777666666665555555555555555444444444444444444444444444444433333333+2428
0 | 0000000000000000000000000000000000000000... | 73,423 |
<p>IMDB uses a Bayesian estimate to compute its top 250 films. Let's say I know all the variables needed to compute this Bayesian estimate for these films. I also have the production company associated with each film. How could I fairly rank the production companies based on the weighted rank (and review counts) of ... | 73,424 |
<p>Official stats on how many videos (rather than how many hours or what volume of data) seem quite hard to come by. </p>
<p>My current idea is something like this:</p>
<p>A youtube URL is like: <a href="http://www.youtube.com/watch?v=w1sjRD7NSec" rel="nofollow">http://www.youtube.com/watch?v=w1sjRD7NSec</a></p>
<p>... | 12,795 |
<p>I am measuring the evolution of the brain response to a visual stimulation over time. The measures are done every seconds from 1 second to 14 seconds (each measure at time t gives a value summarizing the magnitude of the brain response from time 0 to time t). I have 8 subjects and 2 experimental conditions. For each... | 35,796 |
<p>I'm very in to Sports analysis and am keen to look at finessing my analysis models that I have worked up (I don't have a great maths background, I've just done a little bit of reading).</p>
<p>Standard deviation of Game Results about prediction from a Ratings system (in this case least squares regression with a fe... | 73,425 |
<p>I have multiple (finitely-many) variables with independent posterior pdfs $f_{x_1}...f_{x_n}$ based on Bayesian updating treating them as independent with independent evidence.</p>
<p>If I subsequently discover conditional evidence relating the variables and need a joint prior, is there an analogue to a maximum-ent... | 73,426 |
<p>I'm want to show that a customer who buys paper books is more likely to buy an e-reader than a customer who does not buy paper books. Note that the number of e-readers purchased in the past is small (1,000) compared to the total set of events (1,000,000).</p>
<p>Here's the historical data that I have:</p>
<pre><co... | 35,800 |
<p>I'm hoping someone can explain this bit of R code for me related to <code>glm()</code>. I don't understand the diagnostic plot that has been suggested. It seems a more informative plot would be to plot against the fitted values, but maybe I don't understand something.
Here's the code:</p>
<pre><code>result <- gl... | 73,427 |
<p>this is a rather elemental question, but any help would be appreciated anyway.</p>
<p>This <a href="http://www.gifted.uconn.edu/siegle/research/Correlation/alphaleve.htm" rel="nofollow">webpage</a> gives a method of finding the p-value of Pearson's correlation coefficient, using a table. However, the methods liste... | 35,803 |
<p>I would like to compute the Wilcoxon rank-sum test in Stata for two countries of my sample with the dummyvalue 3 and 6. </p>
<p>Can anyone give the right code for Stata? </p> | 73,428 |
<p>I have calculated the correlation between A and B for 10 different subjects. For averaging purposes, I've converted the r-values to z-values using Fisher's z-transformation. </p>
<pre><code>subj zvalue
s1 -0.04
s2 -0.14
s3 -0.29
s4 -0.20
s5 -0.37
s6 -0.01
s7 -0.09
s8 0.20
s9 -0.15
s10 0.09
</code></pre>
<p>I wan... | 47,199 |
<p>I am implementing a Fine & Gray competing risk model. The model includes covariates that are static for each person (e.g. location) as well as covariates that change over time (such as local unemployment rates).</p>
<p>The issue I have is: how do you generate cumulative incidence curves, assuming covariates tha... | 35,805 |
<p>I would like to know how to move forward in establishing a baseline on multiple observed years of retrospective data. My intent is to first identify the 10% of a given group to include in a study, and then establish a baseline.</p>
<p>One concern of the data is that some observations may have an extremely large sco... | 73,429 |
<p>In maximum likelihood estimation (MLE) a useful result is that the standard errors for some estimated coefficient vector can be computed as the square roots of the diagonal entries of the inverse of the negative expected information matrix. </p>
<p>In other words, let the empirical estimate <em>of the expectation</... | 35,807 |
<p>I've got a online classification problem where I predict a class label <code>{+1, -1}</code> for an object and then show it to a user to get a real label. My task is to minimize a number of <code>-1</code> objects shown to a user.</p>
<p>Obviously, the algorithm will not converge if it learns only on <code>+1 ->... | 73,430 |
<p>This question is somewhat of a continuation from an earlier posting:
<a href="http://stats.stackexchange.com/questions/50526/using-em-algorithm-for-record-linking">Using EM algorithm for record linking</a></p>
<p>I have two data sets of individual some of whom are in both but a prior it is not know which are and th... | 35,810 |
<p>I aim to discriminate between three populations by using a maximum likelihood classifier. The idea is that every population has a unique distribution $\hat{f_i} (x)$. The pdf $\hat{f_i}(x)$ has been estimated on a set of training data. A new set of observations $(x_1,...x_p)$ will be assigned to the population for... | 73,431 |
<p>I want to generate some spatial data where the points/location in the space form a multivariate gaussian distribution. I want these points to have certain autocorrelation given by the variogram model like spherical with spill 0.025 and range 15. I then want to generate some sample for this </p>
<p>How can I do it?<... | 73,432 |
<p>I've read <a href="http://www.evanmiller.org/how-not-to-sort-by-average-rating.html" rel="nofollow">How Not to Sort By Average Rating</a> regarding how to average binary positive/negative ratings in a way that takes the number of ratings into account. The author uses the "lower bound of Wilson score confidence inter... | 73,433 |
<p>I have a question about Bayesian Information Criteria. (GARCH models)</p>
<p>I have looked for so many hours but still very confused about this BIC especially a negative one. As far as I am concerned it is okay to have a BIC that is negative, but the interpretation of them are different in each book on website. I a... | 12,798 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.