question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>So I have a dataset which I am using K fold cross validation on to select the number of features and which features should be selected. As I understand it, I would set the number of features to be selected as a constant, then let my feature selection method pick whatever N features it wants to for each fold of cross... | 69,433 |
<p>I have a dataset of roughly 500 features and am training a binary classifier using GBM - gradient boosted machines, an ensemble of decision trees. Of these 500 variables, I am sure some are highly correlated with each other, though probably not to the extent where they are linearly dependent. For example, one vari... | 69,434 |
<p>I'm looking at similarity of samples for non-ordinal/non-parametric data. I've included a dummy dataset below for reference in the question. Neither A, B, or C is ordinal data: it's entirely categorical. Where C is filled in, it shows a Pareto distribution. </p>
<p>The actual dataset is large and a very small subse... | 29,892 |
<p>I am regressing a log-normally distributed dependent variable (<code>wage</code>) on a heavily skewed independent variable and I want to make sure I handle it in the best possible way. The independent variable <code>award</code> is the percentage point (measured 0-100) likelihood that a given person will win a speci... | 69,435 |
<p>I have $N$ time series each of which can be modeled as $$y_{kt}=Ax_{kt}+b+\varepsilon_{kt}\quad(1\le k\le N,1\le t\le T),$$ where $x_{kt}\sim\text{Pois}(\lambda\Delta t)$ and $\varepsilon_{kt}\sim N(0,\sigma^2)$. Parameters $A$, $b$ and $\sigma^2$ are unknown and I want to extract the uncontamined version of all $y_... | 69,436 |
<p>I am running a GLM of about 15 predictor variables and using <code>dredge</code> and <code>model.avg</code> functions of <code>MuMIn</code>. The output, however, is confusing (attached below). I would appreciate your help understand it and/or organize it. Cheers!</p>
<pre><code>> dd<-dredge(model1, beta = FAL... | 69,437 |
<p>What would be the distribution of $y$, when:</p>
<ol>
<li>$y = x^2$ and $x\sim\mathcal{N}(\mu, \sigma^2)$.</li>
<li>$y = x^2$ and $x\sim$ Log-$\mathcal{N}$.</li>
</ol> | 69,438 |
<p>Let, $S_{n*n}$ represent a similarity matrix, among $n$ observation, my case n = 215. and $Y=\{y_1, y_2, ...,y_n\}$ contains a response value for each $x_n$ observation. For each observation we have $t$ features,my case t = 50.</p>
<p>Since, the number of observation is not enough vs features to do a nice multiply ... | 236 |
<p>I have a time series which has a very strong upward trend for the first half, then very strong downward for the second half and finishes pretty much back where it started.
Should I split the data in two for analysis - or can I still account for a trend which is net neutral?</p> | 29,901 |
<p>I would like to use a binary logistic regression model in the context of streaming data (multidimensional time series) in order to predict the value of the dependent variable of the data (i.e. row) that just arrived, given the past observations. As far as I know, logistic regression is traditionally used for postmor... | 40,134 |
<p>I have a huge dataset of reaction times from a psycholinguistic experiment, and in separate tables, I have information that I'd like to add in about each word's frequency and things like that. </p>
<p>The main dataset looks something like this:</p>
<pre><code>maindataset <-structure(list(item = c(101, 103, 102,... | 40,135 |
<p>I have a made a linear mixed model using <code>lmer()</code>. </p>
<p>I began with a maximal model containing 6 terms and all two-way interactions (15 total), I also have a random effect of subject ID. Of these terms, 11 interactions were significant and so were kept in the final model. I found this by dropping in... | 69,439 |
<p>I've scraped a set of data, and I was wandering what the best way to start analyzing it was. My initial thoughts were to use a multi y axis graph, like this:</p>
<p><img src="http://i.stack.imgur.com/wrexa.png" alt="http://imgur.com/bFbDIxz"> </p>
<p>The reason I was thinking about a multi axis graph was because i... | 69,440 |
<p>Say we have a nasty probability distribution like,
$$
P(x) = \frac{P^*(x)}{Z}
$$
where we can easily compute $P^*(x)$ for a given $x$ but not $P(x)$ because partition function $Z$ is expensive to compute. There are approximation techniques like Monte Carlo which can be used to estimate the expectation of functions u... | 69,441 |
<p>Is there any popular implementation of logistic regression in R that defaults to using a one vs all approach for a categorical dependent variable with more than two classes? I have specific reasons to favor a one vs all approach vs simply performing a multinomial logistic regression. Also, while I know I can write m... | 69,442 |
<p>I'm looking for a simple explanation of what an elliptical distribution is and how it differs from a non-elliptical distribution. My knowledge of stats is very basic; Wikipedia was not much help on this topic (too technical for my level of understanding). Thanks.</p> | 69,443 |
<p>I'm interested in finding out a method for generating correlated, non-normal data. So ideally some sort of distribution that takes in a covariance (or correlation) matrix as a parameter and generates data that approximates it. But here's the catch: the method I'm trying to find should have the flexibility to also co... | 29,910 |
<p>I'm using a free version of Bayesian network software called Netica. It allows only 15 nodes for the free version. Do you know any other software or R package that generate a kind of graph below using a dsc file?</p>
<p><img src="http://i.stack.imgur.com/uetJn.png" alt="network graph"></p>
<p>I know R package call... | 69,444 |
<p>I came across interesting <a href="http://goo.gl/1DBkh" rel="nofollow">article</a> on application of canonical correlation analysis (CCA). Authors apply classical CCA on a mixed variables dataset (both independent and dependent sets include continuous and binary variables).</p>
<p>To sum up their main contribution:... | 29,914 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/20359/sine-wave-with-a-constant-period-what-else-is-constant">Sine wave with a constant period: what else is constant?</a> </p>
</blockquote>
<p>Which statistic that you can calculate on a window remains c... | 29,916 |
<p>I have a pdf function as follows:
$$\dfrac{1}{s+a-b} [bs e^{-bt} + (a-b)(s+a)e^{-(s+a)t}]$$
I want to fit this against a weibull pdf with shape=1.12 and scale=461386. I want to calculate the values of s,a and b. Is there any standard tool for doing this?</p>
<p>Prasenjit</p> | 69,445 |
<p>I have the neuropsychiatric questionnaire scores of 300 individuals, of which 200 are normal, and 100 have the disease. The questionnaire is divided into 12 categories (delusion, agitation, ... etc). And each category begins with a question along the lines of: does the patient experience delusions? (yes=1, no=0, a b... | 69,446 |
<p>I've read in a couple places about people using residuals from predictions of other models to improve the model's accuracy. Anyone have a link about how to carry this out in R, ideally with some example code?</p>
<p>UPDATE: This is in the context of reading the papers about the Netflix prize where k-nearest neigh... | 40,150 |
<p>I would like to use the Sequential Sum of Squares test. But the degree of freedom for the denominator is (n - p - 1), where n = number of samples, and p = number of variables in the full model.</p>
<p>What do I do when p > n?</p> | 69,447 |
<p>I am currently constructing a regression model meant to predict a given dependent variable - call it IN. I will also be constructing a model with the same independent variables to predict a second dependent variable - call it OUT. I would like to examine the difference between coefficients for the same independent v... | 69,448 |
<p><strong>First of all:</strong>
From what I understood, bootstrapping residuals works as follows:</p>
<ol>
<li>Fit model to data </li>
<li>Calculate the residuals</li>
<li>Resample the residuals and add them to 1.</li>
<li>Fit model to new dataset from 3.</li>
<li>Repeat <code>n</code> times, but always add the res... | 69,449 |
<p>When forecasting a moving average (MA) model using R's <code>forecast</code>, why does using <code>residuals(fit)</code> produce different results than <code>forecast</code> does? The question is very similar to (<a href="http://stats.stackexchange.com/questions/20254/ma-terms-in-arima">MA terms in arima</a>), but t... | 69,450 |
<p>I have been trying to run a multilevel model with both a linear and a quadratic term for income as my main variables of interest. It looks something like:
\begin{eqnarray}
&&y_{ij}=\beta_{0j}+\beta_{1j}\text{Income}+\beta_{2j}\text{Income}^2+\epsilon_{ij}\nonumber\\
&&\beta_{0j}=\gamma_{01}\text{Leve... | 29,919 |
<p>I asked a previous question about why the ML and MAP estimates are the same when using a uniform prior (<a href="http://stats.stackexchange.com/questions/64259/how-does-a-uniform-prior-lead-to-the-same-estimates-from-maximum-likelihood-and">How does a uniform prior lead to the same estimates from maximum likelihood ... | 29,921 |
<p>I am planning to do a 2-way mixed ANOVA with the within-subjects factor having four levels. Since the exact data do not matter, I hope to suffice by only providing a general question.</p>
<p>On my endeavours through the internet and different textbooks on statistics I have come to the point that I would like to com... | 5,790 |
<p>This question concerns an implementation of the topmoumoute natural gradient (tonga) algorithm as described in page 5 in the paper Le Roux et al 2007 <a href="http://research.microsoft.com/pubs/64644/tonga.pdf" rel="nofollow">http://research.microsoft.com/pubs/64644/tonga.pdf</a>.</p>
<p>I understand that the basi... | 69,451 |
<p>As I know OVB, from a frequentist education, when you leave a variable $(z)$ out of your control set $(X)$ that is correlated with both your independent variable of interest (treatment $T$) and your dependent variable of interest ($Y$), your coefficient estimate will be biased because the explanatory power of the mi... | 29,924 |
<p>I am trying to simulate remission times for 100 patients from an exponential distribution with mean 1 year. I also want to simulate after-remission times for these 100 patients. But it is very much likely in the real life scenario that those who remit quickly are likely to have comparatively longer after-remission t... | 69,452 |
<p>I'm looking for a distribution to model a vector of $k$ binary random variables, $X_1, \ldots, X_k$. Suppose I have observed that $\sum_i X_i = n$. In this case I do not want to treat them as independent Bernoulli random variables. Instead, I would like something like the multinomial:</p>
<p>$P(X_1=x_1, \ldots, ... | 69,453 |
<p>I want to do an a priori analysis of minimum sample size with G*Power and I have two questions about this:</p>
<p>First, I will test an interaction effect for a moderator variable. I am not sure which statistical test to choose in G*Power as I am less interested in the overall $R^2$ and more interested in whether t... | 69,454 |
<p>Are there any good books for me to learn probability programming?
For example, I am new to Latent Dirichlet allocation (LDA) and Gibbs sampling. I have read some books about the techniques, but it still feels hard to
develop programs to apply them. Are there any books that can help?</p>
<p>I have taken some course... | 69,455 |
<p>I recently played on a betting site (soccer games) and wondered how they change odds so quickly on sporting events. I get the basics of betting, but wonder how they change live betting odds so quickly? </p>
<p>Do they use variables as morale, ball possession, ... ? </p>
<p>And if thats the case how do they calcul... | 32,531 |
<p>I am working on disease infection data, and I am puzzled on whether to handle the data as "categorical" or "continuous".</p>
<ul>
<li>"Infection Count"
<ul>
<li>the number of infection cases found in a specific period of time, the count
is generated from categorical data (i.e. no. of patient tagged as "infecte... | 29,929 |
<p>Link to picture: <a href="https://www.dropbox.com/s/bxzxy0y37npqc4o/SEM%20problems.PNG" rel="nofollow">https://www.dropbox.com/s/bxzxy0y37npqc4o/SEM%20problems.PNG</a></p>
<p>Need a bit of help determining what I should do to fix this problem: The SEM wont run because it believes it's non-positive definite. Meaning... | 49,830 |
<p>I'm sorry if I cannot formulate the problem precisely.</p>
<p>Let us consider an ordered set $Q$ with $n_q$ elements, and a number of its (possibly overlapping) subsets $B_1, \dots, B_k$. For a given $i$, one is interested in the question whether the ranks of set $B_i$ are uniformly distributed in $Q$, or whether t... | 69,456 |
<p>Suppose I am interested in the prevalence of drug use in a population over time, but I am unable to conduct audits (sample some transactions at random and check to see if drugs were exchanged). I do have data on seizures, needles or vials found in the park, as well as crime hotline reports, but these are not perfect... | 69,457 |
<p>What is difference between using various cost functions: LMS,Cross entropy in neural networks? All of them have same derivative w.r.t final activation and hence all the gradients are still gonna remain same?</p> | 5,792 |
<p>I'm trying to cluster a list of records based on a (percentage) frequency distribution of variables which add up to 100%.
Like</p>
<ol>
<li>Record1 - VarA(25%) VarB(25%) varC(50%) varD(0%)</li>
<li>Record2- VarA(50%) VarB(15%) varc(0%) VarD(35%) </li>
</ol>
<p>and so on.
I have standardized variables before whil... | 17,931 |
<p>I'm new to neural networks and machine learning and I was wondering how you use time series data to set the weights of a regular FNN, and how you use the ending weights to forecast the time series. In essence how can you transform the time series data into weights and back again for the output.</p> | 69,458 |
<p>I'm a stats newbie so I hope this question isn't too easy for you! :) I'm not sure how to ask it so I've written two versions: the short version is a pure stats question and the longer version explains my application.</p>
<h2><em>The short version:</em></h2>
<p>I have two sets of probabilities. The first set has a... | 69,459 |
<p>I've fit a model with lm(), and I now want to analyze it to see where it's overfit, etc... I'm imagining a plot that has the index of each observation on the x-axis, and the corresponding responses plotted as points on the y-axis. In (vertical) line with each point is a set of colored lines stacked on top of each ot... | 29,936 |
<p>I am trying to get predictions for observations from a lme object. This is
supposed to be quite straightforward. Yet, since I am get different types of errors for different trials, it seems to me I am missing something. My model is the following:</p>
<pre><code>model <- lme(log(child_mortality) ~ as.factor(clu... | 38,813 |
<p>My question is the following. Let's say I have two probability distributions:</p>
<p>$f(x|b), g(x|c)$</p>
<p>$b$ and $c$ are discrete events while $x$ is a continuous variable, i.e., when the button b is pressed there is some distribution for the amount of rain fall the next day, $x$. </p>
<p>When the button $c$ ... | 69,460 |
<p>How are (linear) mixed effects models normally compared against each other? I know likelihood ratio tests can be used, but this doesn't work if one model is not a 'subset' of the other correct?</p>
<p>Is the estimation of the models df always straightforward? Number of fixed effects + number of variance components ... | 69,461 |
<p>Because I find them fascinating, I'd like to hear what folks in this community find as the most interesting statistical paradox and why.</p> | 69,462 |
<p>What would be the best way to display changes in two scalar variables (x,y) over time (z), in one visualization?</p>
<p>One idea that I had was to plot x and y both on the vertical axis, with z as the horizontal. </p>
<p>Note: I'll be using R and likely ggplot2</p> | 69,463 |
<p>The title is quite self-explanatory - I'd like to know if there's any other parametric technique apart from repeated-measures ANOVA, that can be utilized in order to compare several (more than 2) repeated measures?</p> | 29,941 |
<p>I want to guarantee a parsimonious random forest (few features used). What are methods to do this? It was suggested to me to get the feature importance after the model was created, and then create a new model using only the important features. Is this a good idea/what other options are there?</p> | 69,464 |
<p>I have a noob question for you. I have run two experiments: A and B. Between the two experiments I changed an element which should <em>not</em> change the results. I want to check that the results of experiment B do not contradict the results of experiment A.</p>
<p>The results for each experiment are a series of i... | 69,465 |
<p>Is there a way to retrieve the R square value from a <code>ctree</code> model? Or is this impossible with how the function runs? </p>
<p>Thanks! </p> | 69,466 |
<p>I ran <a href="http://www.maizegenetics.net/tassel/" rel="nofollow">Tassel3</a> and I filtered results with p-value
not more than 0.05. This way, it is ok to draw a Manhattan plot. However, for
a QQ-plot there is a problem. </p>
<p>Say I have 40 thousands SNPs, after filtering, about 1,800 SNPs were
kept in the ... | 69,467 |
<p>One of the most widely used interpretation of effect size is Cohen's $d$, as follows:</p>
<ul>
<li>$<.10$: <em>trivial</em></li>
<li>$[.10,.30]$: <em>small to medium</em> </li>
<li>$[.30,.50]$: <em>medium to large</em></li>
<li>$>.50$: <em>large to very large</em></li>
</ul>
<p>This appears to be the standar... | 40,176 |
<p>I have some <strong>GPS coordinates series</strong> taken in regular time steps and I need to verify whether some chunks of the trajectories fit well as a <strong>straight line</strong> or not. The aim is to perform <strong>segmentation</strong> on each trajectory, I am already able to find hard curves quite well, b... | 69,468 |
<p>For example, in linear regression, we assume the errors are normally distributed, have constant variance and have an expected value of 0. These assumptions all refer to the population. But we look at our actual data points to see if these assumptions are satisfied, Why do we do this? How do we know that results hold... | 69,469 |
<p>Having read numerous texts regarding neural networks and their characteristics, I am getting increasingly confused, paradoxically β I am looking for a brief explanation or references to the right sources.</p>
<p>I am trying to implement neural networks using PyBrain to <strong>recognise patterns in biometric data a... | 69,470 |
<p>I am doing an NMDS ordination. The data come from a number of sites scattered around two lakes. In the plots, I coloured the samples from the two lakes blue and green. There seems to be some pretty decent separation between the lakes in the NMDS ordination plot. However, when I use lakes as a factor variable with en... | 69,471 |
<p>From <a href="http://core.ecu.edu/psyc/wuenschk/stathelp/PowerAnalysis_Overview.doc" rel="nofollow">a note</a></p>
<blockquote>
<p><strong>A Priori Power Analysis.</strong> This is an important part of planning research. You determine how many cases you will need to have a good chance of detecting an effect of ... | 69,472 |
<p>I'm working with some modeled future stream flow data that was created in two steps. First, future precipitation predictions (at certain points in a watershed) were created by running historical precipitation data through four precipitation models. The output from those models (four runs per precipitation model) w... | 29,946 |
<p>According to experimental result, One approach has 10% better accuracy over the other.
My supervisor said that this should be coupled with an estimative of the statistical significance of this increase (p-value) according to the size of the dataset.</p>
<p>Do you guys have any idea how to calculate statistical sign... | 69,473 |
<p>As I understand, most of the research is centralized through the U.S. Census Bureau. However, I couldn't find any overview of fields of research on their website. Is there any other institution or website that summarizes the research that has been done?</p>
<p>I'd especially like to know which data is of most inter... | 29,948 |
<p>In R, if I write</p>
<pre><code>lm(a ~ b + c + b*c)
</code></pre>
<p>would this still be a linear regression? </p>
<p>How to do other kinds of regression in R? I would appreciate any recommendation for textbooks or tutorials?</p> | 69,474 |
<p>I'm doing a linear regression with a transformed dependent variable. The following transformation was done so that the assumption of normality of residuals would hold. The untransformed dependant variable was negatively skewed, and the following transform made it close to normal: </p>
<p>$$Y=\sqrt{50-Y_{orig}}$$</p... | 41,763 |
<p>I've asked this question on <a href="http://stackoverflow.com/questions/22767945/fitting-logistic-function-with-pymc">stackoverflow</a> too, but no answer yet. This seems a more appropariate place to ask this question:</p>
<p>I'm messing around with pymc to understand it a bit better. Now I am trying to fit a logis... | 69,475 |
<p>I'm having some problems with the following assignment:
I have a sample selection model (tobit II model) which however does not have the standard tobit II representation but rather the sample selection model is described by
y=1(xΞ΄+u>0)e^(xb+e), where 1(.) is an indicator function taking the value of 1 if the argumen... | 10 |
<p>I am doing GWAS SNP association studies on diseases by using a software called plink (<a href="http://pngu.mgh.harvard.edu/~purcell/plink/download.shtml">http://pngu.mgh.harvard.edu/~purcell/plink/download.shtml</a>).</p>
<p>With association results I get p-values for all the SNPs that was analyzed. Now, I use a QQ... | 69,476 |
<p>(I am fully aware that my topic may not be relevant here, do let me know if this is true.)<br/>
I am a research staff with training in epidemiology and biostatistics, working in government organization on public health matters like disease surveillance and infection control. Being a research staff here keeps giving ... | 69,477 |
<p>We have a case to map real input values into low dimensional binary vectors. So we use CDBN here, but whatever I change the parameter combinations of k, lr or epochs, it always failed to classify our dataset. So we change our implementation from our own code to deeplearning4j, but it fails also.</p>
<p>Under such a... | 69,478 |
<p>Given two sets of data of user activity, both of which appear to be in an exponential distribution, I have calculated the mean and standard deviations using both a mean/deviation and a sample mean/deviation <code>(sample size = 30, number of samples = 10k)</code>:</p>
<hr>
<h3>A <code>(size: 627,000)</code>:</h3>
... | 29,960 |
<p>I have a data set of medical drug stock levels at health centres and I want to forecast monthly consumption over the following 3-6 months. However about 30%-40% of the data is missing and some of the reporting intervals are irregular. Several other variables can potentially be used to further predict consumption. I'... | 29,961 |
<p><a href="http://en.wikipedia.org/wiki/Heteroscedasticity-consistent_standard_errors" rel="nofollow">Wikipedia</a> and the R sandwich package <a href="http://cran.r-project.org/web/packages/sandwich/index.html" rel="nofollow">vignette</a> give good information about the assumptions supporting OLS coefficient standard... | 69,479 |
<p>I have some practice homework questions. I did the first one I will go over the steps please tell me If I am doing it right.</p>
<p>a) As mentioned earlier, it is claimed that 70% of households in Ontario now own large-screen TVs. You would like to verify this statement for your class in mass communications. If yo... | 69,480 |
<p>I have been dealing with the following problem. I have kind of a real time system and every time frame I read its current value, creating a time series (such as 1, 12, 2, 3, 5, 9, 1, ...). I'd like to know methods (statistical and machine learning) to forecast the next value in an online fashion (meaning every time ... | 40,191 |
<p>Experience raising Labrador puppies revealed that the weight of the puppies at six months follow a normal distribution. The subsequent weights (in pounds) of a small sample of seven six-month puppies were:</p>
<p>$$ \begin{array}{|c|c|} \hline \mbox{Puppy #}& \mbox{Weight} \\ \hline 1 & 16 \\ 2 & 46 \\ ... | 69,481 |
<p>In my analysis I'm using a linear regression with a log transformed dependent variable. I've included an interaction term in my regression model as I'm testing for interaction between particular independent variables. The model is as follows:</p>
<p>ln(Y) = Ξ± + Ξ²X1 + Ξ²X2 + Ξ²X3 + Ξ²X4 + Ξ²X5 + Ξ²(X1*X2)</p>
<p>with co... | 69,482 |
<p>Suppose to have a bivariate variable $z_t=(x_t, y_t)$ indexed by $t=1,2, ..., T$. Suppose now that the two components have different support, i.e. in my specific problem $x_t \in \mathcal{S}$, where $\mathcal{S}$ is a circle, and $y_t \in \mathcal{R}$. I estimate a model (Bayesian hidden Markov model) and then i wa... | 5,799 |
<p>Everywhere I have read that if you want to test the hypothesis of dependence of a binary outcome on your data, you should not apply ANOVA (if its incorrect, please let me know). We can apply logistic regression, chi square testing etc.</p>
<p>I have come across a paper in the reputed <strong>Journal of Vision</stro... | 40,193 |
<p>I read in an article that the logit link is considered
suitable for analyzing ordered categorical data evenly distributed among all categories.</p>
<p>I want to do ordinal logistic regression and I have an ordinal variable on the scale of 0-10 and have to make three groups, 0-6, 7-8 and 9-10. Does this mean that th... | 69,483 |
<p>It is well established, at least among statisticians of some higher calibre, that models with the values of the AIC statistic within a certain threshold of the minimum value should be considered as appropriate as the model minimizing the AIC statistic. For example, in [1, p.221] we find </p>
<blockquote>
<p>Then ... | 69,484 |
<p>I have the data in the form of $Y \in \mathbb{R}^T$ a time series. For each point in time I have $ m $ real features $ f_i \in \mathbb{R}^m$. I want to use the following model to fit the data
$ \hat{y}_t = \langle (y_{t-1}, ..., y_{t-h}), W_u(f_t)\rangle + B_v(f_t)$
where $ W $ stands for weight and $ B $ stands for... | 69,485 |
<p>I am trying to model a logistic regression on data predicted from the results of a previous logistic regression, and am having trouble figuring out how to do it, either in OpenBUGS (BRugs) or JAGS (with rjags). I'm attempting to determine the probabilistic maturation reaction norms (PMRNs) of different fish populat... | 69,486 |
<p>I have come upon a paper where a VAR analysis is performed. Using 3 endogenous variables and some exogenous (control) variables, the results of the VAR analysis are shown in a table. </p>
<p>For the endogenous variables four lags are selected according to different selection criteria. However, in the estimation res... | 69,487 |
<p><p>
Suppose $l(b; y)$ is the log-likelihood function we want to maximize, i.e. we want to
solve $U = l' = 0$ for the ML estimation of $b$. Using Newton-Raphson method, we
have</p>
<p>\begin{align*}
b^{(m)} = b^{(m-1)} - \frac{U}{U'},
\end{align*}</p>
<p>This can be again approximated by:
\begin{align*}
b^{(m)} = b... | 69,488 |
<p>I have two variables: Drug Name (DN) and corresponding Adverse Events (AE), which stand in a many-to-many relation. There are 33,556 drug names and 9,516 adverse events. The sample size is about 5.8 million observations.</p>
<p>I want to study and understand the association/relationship between DN and AE. Iβm th... | 38,973 |
<p>I am hoping to confirm that I have a suitable way to analyse the different proportions of people who are categorized as left lateralised on the one hand, or bilateral/right lateralised on the other in two different tasks. </p>
<p>I cannot use an ordinary logistic regression (or chi square test) as the conditions a... | 69,489 |
<p>I am currently trying to learn how to estimate the kernel density using the Epanechnikov kernel in MATLAB, and I am currently having problems with my code. What I'm doing is that the data that I am simulating comes from a mixture of normals. When I tried to estimate it using a Gaussian kernel, the code worked. Howev... | 69,490 |
<p>I recently posted <a href="http://stats.stackexchange.com/questions/32498/pca-with-all-categorical-factors-prior-a-regression-with-a-continuous-response">a question</a> with many parts and I'd like to focus in on just one issue that I didn't emphasize in the original post.</p>
<p>My data is a list of records, each ... | 37,601 |
<p>I am a beginner in statistics with just basic knowledge. I have these data: cases, deaths and CFR (Case Fatality Rate-deaths per 100 cases) of a disease for 17 years (1994-2010) from 2 neighbouring states where people can walk across the states freely. This is a population based cohort study.</p>
<p>Data are availa... | 879 |
<p>I've looked for this answer around the web with no luck so far. I'm mostly interested in how time trends apply to cross-section and panel data. </p>
<p>Thanks</p> | 29,975 |
<p>I have a quarterly time series and test for stationarity with an augmented Dickey-Fuller test using R.</p>
<pre><code>adf.test(myseries)
# returns
# Dickey-Fuller = -3.9828, Lag order = 4, p-value = 0.01272
# alternative hypothesis: stationary
</code></pre>
<p>so the H0 is rejected. I tried to validate this intui... | 69,491 |
<p>I would like to analyse the following type of experiment using a two-level fully nested ANOVA. We have mice of two genotypes (Group factor) and for each of the genotypes we take a certain number of mice (sub-groups) and measure several identical samples per each mouse. Thus it looks like a classic two-level nested d... | 29,977 |
<p>The question is the following:</p>
<blockquote>
<ol>
<li><p>Our regression model can be written as $y_i = \beta^Tx_i + \epsilon_i, 1 \leq i \leq n$. Find the $100(1- \alpha)\%$ confidence interval for the mean response $\beta^Tx$ at a given vector $x$ of regressor observations.</p></li>
<li><p>Now suppose a ... | 69,492 |
<p>I have a log-log scale plot by gnuplot. With following ranges,</p>
<pre><code>set xrange [1:1000]
set yrange [1:1000]
</code></pre>
<p>How do I draw slope 5/3 slope, ie, a slope that intersects y-axis at 5 and x-axis at 3?</p>
<p>Many thanks!</p> | 29,979 |
<p>Having studied parametric Bayesian statistics during the two last years, I plan to begin to self-study non parametric Bayesian model during this summer and look for recommendations. I would like the book(s) to cover both the theoritical aspects and the practical ones (with implementation, examples of models ...) Tha... | 30,151 |
<p>I will describe my question with an example:</p>
<p>A machine manufactures toys and places them on a conveyor belt. A toys expert overlooking the conveyor belt observes the toys. If a toy is faulty he can successfully detect it with probability $P_{d}$. It is possible to have more experts overlooking the process.</... | 69,493 |
<p>For this non-linear equation</p>
<p>$$y = a\left(1-\exp\left(-\left(x/b\right)\right)\right)^c$$</p>
<p>by using least square estimated values for the parameters are obtained and</p>
<pre><code>x <- c(3, 33, 146, 227, 342, 351, 353, 444, 556, 571, 709, 759, 836,
860, 968, 1056, 1726, 1846, 1872, 1986, 2311, 2... | 69,494 |
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