question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>I have totally <code>696,876</code> nodes in set <em>X</em>. I have <code>8,127,040</code> nodes in set <em>Y</em>. I am constructing an edge between set <em>X</em> and set <em>Y</em>. After constructing the edges between the 2 sets, I have <code>546,255</code> edges between set <em>X</em> and set <em>Y</em>. </p>
... | 29,666 |
<p>I want to evaluate the effect of three factors (one categorical, and the other two continuous) on the response variable, which is a count data. I have performed 7 candidate GLM models with quasi-Poisson. The models (hypothetically) are the following:</p>
<pre><code>fit1 <- glm(response ~ factor1 * factor2 * fact... | 29,667 |
<p>I have 6 variables ($x_{1}...x_{6}$) that I am using to predict $y$. When performing my data analysis, I first tried a multiple linear regression. From this, only two variables were significant. However, when I ran a linear regression comparing each variable individually to $y$, all but one were significant ($p$ any... | 69,266 |
<p>I'm just wondering if it's possible to analyse and interpret variables that have been transformed using different transformations (eg log and square-root) or if all variables in the analysis have to have been transformed with the same method in order to interpret the results.
Thanks,
Suzie</p> | 69,267 |
<p>I have several streams of time-series data representing sensor readings that are usually closely correlated (at least in the casual usage of the term) though with different scalar multipliers applied. For example, say I have time-series A, B, and C representing historical sensor readings over time. B might be consis... | 871 |
<p>I'm currently trying to draw floating numbers from a uniform distribution.</p>
<p>The Numpy provides numpy.random.uniform.</p>
<pre><code>import numpy as np
sample = np.random.uniform (0, 1, size = (N,) + (2,) + (2,) * K)
</code></pre>
<p>However, this module generates values over the half-open interval [0, 1).</... | 69,268 |
<p>Suppose we have a binary variable $X$ that indicates whether a person ate pizza during the week. This variable is recorded for an entire year. So we have $X_{1}, \dots, X_{52}$ values (1 or 0). Suppose I am interested in the number of weeks of the last 4 weeks that a person did not eat pizza. I want to use this to ... | 69,269 |
<p>I am working on this problem in which I have a dataset of n-dimensional examples that come from different and unknown distributions. Given a new sample, I wish to find k examples from the dataset that come from distribution(s) closest to the new sample. Which measure(Kullback-Leibler vs Hellinger Distance) might be ... | 69,270 |
<p>In hypothesis testing for the value of the population mean, when computing type II error $\beta$, if the alternative hypothesis includes many possibilities, is it always the case that $\beta$ is approximated? In other words, when we compute a numerical value for $\beta$, based on the mean from the sample $\bar{X}$, ... | 69,271 |
<p>I am really interested in learning techniques which can help me deal with the problem briefly described below.</p>
<p>I have a two-class {$0,1$} classification problem.</p>
<p>Most of the object attributes are incremental in time:
when new object appears we know very little about it;
as time passes by its "increme... | 29,672 |
<p>Let's say I generated 2*n values $X_{1},X_{2},...X_{n},Y_{1},Y_{2}...Y_{n}$ from a normal distribution N(10,15) and n = 10,100,1000,20000 and fitted the regression line. Here's some result
$$
n=10, R^{2} =0.03919\\
n=100,R^{2} = 0.004381\\
n=1000, R^{2} = 0.0001705\\
n=20000,R^{2} = 2.386e-06
$$
from the result as... | 69,272 |
<p>I have been trying to solve this problem for over a year without much progress. It is part of a research project I'm doing, but I will illustrate it with a story example I made up, because the actual domain of the problem is a bit confusing (eye-tracking).</p>
<p>You are a plane tracking an enemy ship that travels ... | 69,273 |
<p>I collected data to find whether the presence or absence of vision, sound, and touch during a task affected the successful completion of that task. However, there were no samples collected where all three senses were absent. So the dependent variable is boolean success but I have a question about how to model the in... | 24,012 |
<p>I have 400 patients and I apply 4 tests to all of them. This gives me a number of positive and negative for each test. I want to compare the tests 2 by 2 to find out if there is any statistically significant difference between them.</p>
<pre><code>Test Pos Neg
1 100 300
2 150 250
3 160 240
4 ... | 49,466 |
<p>I am looking for a package in R that can test for structural Breaks in GARCH models. I have estimated my coefficients with <code>rugarch</code>, and I am highly suspicious that there might be some structural break happening, however I need to test this more formally. </p>
<p>Any help would be appreciated :) </p> | 37,446 |
<p>How can I test whether 2 predictors/covariates in MLR are really useful in prediction using R? I reckon this is something to do with multicollinearity. So would the CAR library function , <code>VIF()</code> be appropriate? or can I just do it using simple <code>lm()</code> + <code>summary()</code>?
Thanks.</p>
<... | 47,631 |
<p>I found this document on the internet: <a href="http://www.projectmgt.com/Files/Article-Uncertainties.pdf" rel="nofollow">Dealing with Project
Uncertainties</a></p>
<p>In this article I read:</p>
<blockquote>
<p>In order for uncertainties to be included in the project estimates it
is necessary to take into ... | 39,842 |
<p>I’ve already written this question, but probably I didn’t specified it well, for this reason I write it again.
I need to use a random walk model (no-change) yt = yt(1+t) to compute
the ratio of RMSFE.
What I would like to do is:</p>
<ol>
<li>Fit the model to the data <code>yt,...,yt+k−1</code> and let <code>yˆt+k<... | 69,274 |
<p>A very practical case. I have 3 parallel inputs/aka data-sets, or you may also call it: A large set of learn cases, each one having 3 parameters/inputs (A, B and C)</p>
<p>All 3 inputs have the same min-max of (-1, 1) but have a very different distributions:</p>
<pre><code>A) has around 98% of its data-points in ... | 29,684 |
<p>I have a time series <em>T</em>.</p>
<p>I also a universe <em>U</em> of time series such that <em>A</em>, <em>B</em>, <em>C</em> ... <em>Q</em> are time series that belong to the universe <em>U</em>.</p>
<p>My problem decomposes into the following sub tasks:</p>
<ol>
<li>Find a subset of <em>N</em> time series f... | 5,122 |
<p>How do I go about doing a multinomial logistic regression when I have 70 million observations? Is it feasible? It seems that R is out of the question due to memory constraints?</p> | 29,686 |
<p>I have a data set of skewed nutrient intake values, from around 7800 individuals, of whom around 3000 had two measures of daily nutrient intake (the others only had one measure), so this is a repeated measures design, very unbalanced. The <code>boxcox</code> transformation in the <code>MASS</code> package in <code>R... | 69,275 |
<p>Does anyone know of an R package or have a way to create phrase nets like this? <img src="http://i.stack.imgur.com/a7uMi.png" alt="enter image description here"></p> | 44,024 |
<p>The spirit of this question comes from "Ordinary Monte Carlo", also known as "good old-fashioned Monte Carlo"</p>
<p>Suppose I have a random variable $X$, with<br>
$$\mu := E[X]\\
\sigma^2:=Var[X]
$$</p>
<p>Both are unknown values, because the probability distribution function of $X$ is unknown (or the computation... | 22,011 |
<p>Background: I want to compare two trading strategies in term of profitability. The red one is an active trading strategy, which involves many entry and exit to a specific market. The blue one is a passive strategy. </p>
<p><img src="http://i.imgur.com/2WrkrVo.jpg?1" alt="Plot 1">
Both portfolios start at some unit ... | 69,276 |
<p>How do I calculate the posterior probability in <code>R</code> for individual observations and then classify the observation if the posterior probability is greater than 0.5?</p>
<p>The model is a logistic regression model in which outcome is pass or fail (0,1). SAT scores and high school GPA were used to predict ... | 29,687 |
<p>I have a set of n variables. Each of these variables an be one of a finite number, m, of values. The number of values is different for each variable and independent. From <a href="http://en.wikipedia.org/wiki/Information_entropy#Definition" rel="nofollow">this definition</a> I can calculate the Shannon Entropy of an... | 29,688 |
<p>Actually, this question is more or less a duplicate of the <a href="http://math.stackexchange.com/questions/527798/why-do-bayesian-networks-use-acyclicity-assumption">one</a> which I have asked on math.stackexchange two days ago. </p>
<p>I did not get any answer there but I think now here is a better place to ask t... | 29,690 |
<p>Basically, I can understand the proofs' details for both inequalities, but still I have no idea why the bound of Hoeffding is sharper than that of Markov? Is there any underlying intuitive that can be explained in "natural language" other than mathematical formulas? </p> | 29,691 |
<p>This is actually related to a more complex question; but I want to re-ask it by trying to simplifying it as possible:</p>
<p>1- We have $n$ dimensional functions of the form $f_n:\mathbb{R}^{n} \mapsto \mathbb{R}$.</p>
<p>2- We have multivariate distributions of $\pi_{n}(x_{1:n})$ for each $n$. We don't know how t... | 69,277 |
<p>Say that a study conducted included 300 type A blood cancer patients, 300 type B blood cancer patients, 300 type C blood cancer patients and 300 healthy people, all selected randomly from clinics' lists. We are then given the blood pressure of each patient and healthy person to check if there's a difference between ... | 29,693 |
<p>My question is about the distribution of the t-statistics in Weighted Least Squares regression.</p>
<p>I'm finding that for a fixed <code>Y</code> and random <code>X</code> and <code>W</code>, the "<em>t value</em>" (t-statistic) reported by R (and separately calculated by hand in matlab) has an absolute value grea... | 69,278 |
<p>I'm performing a case of polynomial regression. I use a power $k$ for the regressors (e.g. marketing spend), which helps me determine the nature of the response curve.</p>
<p>I also need to estimate the coefficient for each regressor.</p>
<p>Consider the simplistic case: $y = ax^k + c$ ; $c$ constant, $a$ a coeffi... | 873 |
<p>I've just implemented a naive Bayesian classifier and found out about the Fisher method (<a href="http://stats.stackexchange.com/questions/31366/linear-discriminant-analysis-and-bayes-rule">Linear discriminant analysis and Bayes rule</a>) while looking for ways to improve it. I'm very new to this field.</p>
<p>My r... | 69,279 |
<p><strong>I have a question about an observed behavior of doing change point detection with the R package cpm on filtered time series (using an moving average):</strong></p>
<p>Currently I’m exploring different methods about change point detection especially methods that already have an R implementation. The main sto... | 29,695 |
<p>I have a document classification problem in which the estimated class proportions in the population are severely unbalanced: the population is ~99% class 0 and ~1% class 1. </p>
<p>I am using a logistic regression classifier (LibLINEAR), and have little flexibility in this decision.</p>
<p>To maximize the classifi... | 69,280 |
<p><strong>Base Data</strong>: I have ~1,000 people marked with assessments: '1,' [good] '2,' [middle] or '3' [bad] -- these are the values I'm trying to predict for people in the future. In addition to that, I have some demographic information: gender (categorical: M / F), age (numerical: 17-80), and race (categorical... | 69,281 |
<p>I have a gene expression dataset with 20 samples, and am not going to be getting any more. There are ~28,000 genes and four clinical covariates associated with each sample. The gene expression values have been Blom transformed and are therefore standard normal distributed. The clinical covariates are normally distri... | 29,702 |
<p>I have binary data input to NN. The weights generated by NN are not normalized, i.e., the weights are not the same for every run of the algorithm. How to standardize these weights?</p> | 69,282 |
<h2>Short version</h2>
<p>How can I partition the variance from the different levels in a nested mixed-effects logistic regression? Preferably using R, but even general principles would be helpful as a start. <a href="https://dl.dropboxusercontent.com/u/2225877/Browne%20et%20al._2005_Variance%20partitioning%20in%20mul... | 69,283 |
<p>Hi: I have a three numeric, continuous variables that are the factor scores that result from a factor analysis of 14 likert items. The analysis suggested three factors. The scores range from about -3 to 3. The scores of the underlying likert items were coded from 0 to 1 (Strongly Agree to Strongly Disagree). </p>
<... | 69,284 |
<p>I have some time series data that shows autocorrelation and seasonality. I want to fit a distribution to it. To use maximum likelihood it needs to be uncorrelated. I first fit a GARCH and an ARIMA model then use
\begin{align}
\hat{y}_t=\frac{y_t-\mu_t}{\sigma_t}
\end{align}
as a filter to get rid of the correlation... | 69,285 |
<p><br>
I'm experimenting with R and found that an anova() needs an object of type lm. But why should I continue with an anova after this:</p>
<pre><code>> x <- data.frame(rand=rnorm(100), factor=sample(c("A","B","C"),100,replace=TRUE))
> head(x)
rand factor
1 0.9640502 B
2 -0.5038238 C
3 -... | 69,286 |
<p>I have a study which gives the hazard ratios for certain interventions like:</p>
<ul>
<li>Intervention 1, HR: .9</li>
<li>Intervention 2, HR: .8</li>
<li>...</li>
</ul>
<p>Is there any way in which I could predict the relative risk for e.g. someone who has intervention 1 and 2? </p>
<p>I think if I assume that th... | 69,287 |
<p>A common measure of effect size used in the social sciences is to look at the standardized difference in means between two conditions (Cohen's d). That is, take the difference in means between two independent samples, and divide that number by their pooled standard deviation.</p>
<p>Here's my question. I wonder if ... | 69,288 |
<p>so we have a0:</p>
<pre><code>>a0[1,1:2]
l11 l12
-0.921 0.389593
</code></pre>
<p>Then; </p>
<pre><code>> is.numeric(a0[1,1:2])
[1] FALSE
</code></pre>
<p>Ok, the text file containing them is a bit of a mess. Then:</p>
<pre><code>> as.numeric(a0[1,1:2])
[1] 131 3
</code></pre>
<p>I <em>know</em... | 39,887 |
<p>Way back when, I used to work in finance, and I remember helping a coworker use some kind of block bootstrap. (I believe the application was: we had weekly data on some financial indicator X, along with weekly data on some stock, and we wanted to measure how well X could be used to predict the stock's movements. And... | 69,289 |
<p>I have just been doing some reading on Gibbs sampling and Metropolis Hastings algorithm and have a couple of questions. </p>
<p>As I understand it, in the case of Gibbs sampling, if we have a large multivariate problem, we sample from the conditional distribution i.e. sample one variable while keeping all others fi... | 69,290 |
<p>I have data from several different measurements of physical performance, each done on the same individual, and I'm looking for ones that correlate with each other. A typical question might be, "does weight-adjusted lean muscle mass correlate with grip strength" ...and so on for each pair of measurements. </p>
<p>Th... | 39,892 |
<p>Here is an example of one zip code I'm working on:
A00100 is the Adjusted Gross Income (aka AGI), agi_class is the size of the adjusted gross income. This ranges from 1 to 7:</p>
<pre><code>1 = 'Under $10,000'
2 = '$10,000 under $25,000'
3 = '$25,000 under $50,000'
4 = '$50,000 under $75,000'
5 ... | 69,291 |
<p>I would be very thankful for advising me how to test statistical significance of coherence coefficients. I have a statistical software that calculates them for me but it does not test their statistical significance.
As far as I know spectral analysis results may be biased and high coherence may not prove anything. ... | 29,710 |
<p>I am emailing for a sanity-check please!</p>
<p>I am analysing some marine wildlife monitoring data from an offshore construction site. The response data are counts of animals (corrected for detection and survey effort), and the model has 2 covariates, both of which are factors: </p>
<ol>
<li><code>Season</cod... | 29,712 |
<p>Many times I have come across informal warnings against "data snooping" (here's <a href="http://goo.gl/mVVNV4" rel="nofollow">one amusing example</a>), and I think I have an intuitive idea of roughly what that means, and why it may be a problem.</p>
<p>On the other hand, "exploratory data analysis" seems to be a pe... | 205 |
<p>Any ideas on other polynomials I could successfully use for applying regression? My goal is a solution that has fit error strictly based on the noise. Is this possible since it is a bell-like curve? The tails can be long, short or non-existent. Am I looking for the impossible? Please note it has been a while since I... | 49,584 |
<p>I am trying to estimate a multimodal gaussian mixture model with an unknown number of nodes. I wish to use a model selection strategy and iteratively test whether incremental modes leads to significantly better fit. An additional forward selection criterion is that the target model should show a sufficient degree of... | 29,714 |
<p><a href="https://en.wikipedia.org/wiki/Kullback%E2%80%93Leibler_divergence#Properties" rel="nofollow">Wikipedia - KL properties</a> says that KL can never be negative. But e.g. for texts where the probabilities are very small I somehow get negative values? E.g. </p>
<p>Collection A:
- word count: 321 doc count: 65... | 29,717 |
<p>I have the model:</p>
<p>$y_t = \alpha + \beta_1 x_t + \beta_2 D_t x_t + \epsilon_t$ </p>
<p>With $y_t$ and $x_t$ as $I(1)$ processes, and $D_t =1$ during a large financial crisis, $D_t = 0$ during non-crisis periods. </p>
<p>I have been asked to test this equation for cointegration. When I test whether $\hat{\ep... | 69,292 |
<p>R is giving me a strange probability for the input</p>
<blockquote>
<p>pbinom(n, 100, prob)</p>
</blockquote>
<p>Any n over 100 seems to cause it to default to 1.
What should I do when my n is greater than 100?</p> | 69,293 |
<p>I am trying to apply PCA (NIPALS method) using <code>Excel</code>. The problem is my results are not exactly matching with the results of <code>R</code>. There is only a difference of sign: if my scores are positive, then scores using <code>R</code> are negative. </p>
<p>I don't know what is going on.
I am unable t... | 49,826 |
<p>I don't know if a similar problem has been asked before so if it has been, please provide me a link to the related/duplicate questions. I am sorry if I seem to be asking too much. But I really like to learn this stuff and this seems to be a good place to start asking.</p>
<p>I have been teaching myself statistics t... | 29,725 |
<p>Assume that $ X_1 , ..., X_n $
is an i.i.d. sample from the population described by a density function $f_x (x,\theta) $ . </p>
<p>Is the sample sufficient for $ \theta $ ?</p>
<p>I know it is a trivial question, but I am in doubt!</p>
<p>Thanks.</p> | 69,294 |
<p>I was going through the book "<a href="http://www.springer.com/statistics/computational+statistics/book/978-0-387-98140-6" rel="nofollow">ggplot2</a>" and i got stuck at point where in chapter 3 where writer talks about two different kinds of transformations(scale and statistical), although i understood the context ... | 69,295 |
<p>I am working on clustering of data streams. For my purpose <a href="http://www.teco.edu/tea/unsup/overview.html#Sequential_Leader_Clustering_Algorithm" rel="nofollow">Sequential Leader Clustering (SLC)</a> have given fair result, as i need not give number of clusters (like k in k means), which require some prior kno... | 29,726 |
<p>I have generated a list of 3 random number where each summed to 1. I would like to access the quality of randomness. What is the best mechanism to access this randomness? E.g my random numbers are. Any idea what tools can I use excel for this?</p>
<pre><code>0.4 0.5 0.1
0.2 0.3 0.5
0.6 0.2 0.2
0.5 0.2 0.3
0.2 0.4 0... | 29,727 |
<p>I am wondering if there is a way to interpret an interaction term from the coefficients rather than just looking at the survival curves? </p>
<p>The factors involved are A, B, and C, which are all binary coded (0,1). I therefore have 8 treatment groups (and survival curves). </p>
<pre><code>1. a0:b0:c0
2. a1:b0:c0... | 69,296 |
<p>I'm not sure why in <em>Mostly Harmless Econometrics</em>, <a href="http://books.google.com/books?id=ztXL21Xd8v8C&lpg=PA55&vq=average%20causal%20effect%20of%20a%20one%20year&pg=PA55#v=onepage&q&f=false" rel="nofollow">last paragraph of p. 55</a>, the expectations of $f_{i}(s-4)$ is taken and the ... | 69,297 |
<p>Let us say we have 2 independent trials with two different coins. </p>
<ul>
<li>In sample A, coin 1 is tossed 20 times and we record 6 heads and 14
tails. </li>
<li>In sample B, coin 2 is flipped 30 times and we record 20 heads and
10 tails.</li>
</ul>
<p>H0 is that both underlying distributions for experiment... | 24,027 |
<p>I am using regression, and trying to create a construct. I have two continuous variables but they are each skewed/not normally distributed. I have $\log_{10}$ transformed each of them separately. Is it appropriate now to add them together to arrive at the measure for my construct? </p>
<p>If I cannot add them toge... | 69,298 |
<p><strong>Background:</strong> I often find that when working with JAGS that I end up with a lot of JAGS scripts as I explore different models. After a while I might settle on a set of models that I'm going to report, but then there is the issue of keeping settings consistent across these models that are meant to be c... | 69,299 |
<p>I am assessing the performance of a hospital ward over 6 years. There have been two sets of changes to the ward over this time: after year 2 and after year 4. </p>
<p>I have collected data in 4 sample months for each of the three time periods (baseline, following change 1, and following change 2). The denominator d... | 69,300 |
<p>Hopefully this is the right place to ask my question.
I am reading this paper about cold-start recommendations: <a href="http://dl.acm.org/citation.cfm?id=1352837" rel="nofollow">http://dl.acm.org/citation.cfm?id=1352837</a></p>
<p>the expression "aspect model" is used a lot : in the abstract (sentence before last... | 69,301 |
<p>Elzinga's turbulence measure (<a href="http://mephisto.unige.ch/pub/TraMineR/doc/TraMineR-Users-Guide.pdf" rel="nofollow">TraMineR User's Guide, p. 85</a>) is the log2 of the number of "distinct subsequences that can be extracted from the distinct state sequence" multiplied by "the variance of the consecutive times ... | 876 |
<p>I need to test some before and after data, to see if there is a significant shift (n = 114) but the data differences are not normally distributed (or, at least, a histogram would seem to indicate that). Can I use a paired t-test?</p> | 69,302 |
<p>I have a likelihood that is modelled using the IID distributed noise assumption. Now the likelihood at a 3D location $i$ is normally distributed with 0 mean and some precision $\sigma$. So, I can write it as a product:</p>
<p>$$
L(E) \propto \prod_{i} \exp^{-0.5 * e_i \sigma e_i}
$$</p>
<p>Now each location $i$ i... | 69,303 |
<p>I'm very new to multilevel-hierarchical models and I've been reading papers by Andrew Gelman and al. (e.g. "State-Level Opinions from National Surveys" Park, Gelman et al. - Public opinion in state politics, 2006) about inferring state level opinions from federal polls using multilevel hierarchical models. I'm curio... | 36,113 |
<p>I'm trying to exclude the outliers using 2-sigma rule and I have a time series.
So I use a moving average for this.</p>
<p>Let's say I have this: </p>
<pre><code>W1 38 315
W2 48 002
W3 47 487
W4 50 977
W5 39 604
W6 46 058
W7 45 718
W8 22 408
</code></pre>
<p>and I want to exclude outliers. I calculate MVA for 8 ... | 69,304 |
<p>I'm trying to estimate a multivariate normal distribution using a training set of 10.000 examples with 50 features. The observations belong only to 2 classes. I am using a subset of <a href="http://archive.ics.uci.edu/ml/machine-learning-databases/00199/" rel="nofollow">this dataset</a>.</p>
<p>After calculating th... | 69,305 |
<p><strong>Question:</strong> Assume $X$ and $Y$ are independent random variables. Is $Median(XY) = Median(X) \cdot Median(Y)$? If so, how would one prove this? If not, what conditions would be sufficient for this relationship to hold?</p>
<p><strong>Additional question:</strong> Does the relationship hold for $\alpha... | 69,306 |
<p>I have developed a questionnaire having 20 questions. Each question has 5 options. My sample size is 100. These questions are related to 5 determinants. The first determinant is the main attribute and all other determinants are directly proportional to it.
Now I want to perform analysis on SPSS. </p>
<p>Kindly guid... | 69,307 |
<p>In the Exercise 1.4b of <a href="http://goo.gl/cG52mf" rel="nofollow">Gelman's Bayesian Data Analysis (Third Edition)</a> and according to <a href="http://goo.gl/h5idm0" rel="nofollow">its solution</a>, it says to use a normal approximation for $d =$ (score differential $-$ point spread): $d \text{~N}(0, 13.86^2$).<... | 69,308 |
<p>I have 12 people, 6 in treatment group and 6 in control group. They gave ratings (1 to 7) to 8 different activities they were performing as a part of the experiment. </p>
<p>I looked at another thread here which suggested using Mann Whitney U Test for testing variance in responses. However, I found that people in l... | 69,309 |
<p>What are the steps involved in the use of Kalman filters in state space models? </p>
<p>I have seen a couple of <a href="http://jeanpaul.renne.pagesperso-orange.fr/pdf/present_sspace.pdf" rel="nofollow">different</a> formulations, but I'm not sure about the details. For example, <a href="http://rads.stackoverflow.c... | 69,310 |
<p>I'm statistics newbie and any help in picking a good method to analyze the data that I have would be very welcome:</p>
<p>We have a customer that has an active Facebook page, that gets posted on regularity. I have data on their last, say, 200 posts (from the last month) - how many likes the post got and time it was... | 69,311 |
<p>I need some hand to solve this problem.</p>
<p>Suppose a queue can be filled by three type objects (M, F and A). Depending on the number of each objects the line length can be different.</p>
<p>We are looking after the average expectation distance of nearest M and F in any line with given number of $\textit{M,F,A}... | 29,741 |
<p>The data I have are the ages male or female won an award (79 data points, ages, for each gender). When constructing a freq table I used to find the number of classes,
$$ n = 79 $$
$$ \frac{\log(n)}{\log(2)} +1 \approx 8 $$</p>
<p>to find the class width for each gender</p>
<p>$$ \frac{max - min}{8} $$</p>
<p>The ... | 69,312 |
<p>I’m somewhat lost as to how to approach a problem I have and was hoping someone can suggest the most appropriate method.</p>
<hr>
<p>The problem:</p>
<p>I have a data set consisting of concentration values for 8 molecules. These are measured on approx. 230 samples from approx. 70 patients. For many patients there... | 69,313 |
<p>I have a dataset containing non-normally distributed variables that I want to feed into a distance-based classifier (e.g. K-means). Is it ok to just subtract the mean and divide by the standard deviation to "standardize" it? Or should some other transformation be performed? Is it even necessary to standardize the da... | 29,742 |
<p>I wish to use raw data about clinical trials for the end year examination of my master students. These data could deal with any kind of molecule as long as the trials were complete (Phase 1 to 4).</p>
<p>Do you have an idea where to find such a free dataset on the web ? </p>
<p>Thank you.</p> | 37,500 |
<p>I have some doubts about cross validation and scoring a new set of observations.</p>
<p>Let's say I want to predict $y=b_0 + b_1x_1$ and have built a 10-fold cross-validation data set, run a regression model and calculated RMSE, MAE, CV and R-squared and let's say I am happy with results.
Now I have 10 regression m... | 69,314 |
<p>Assuming I have a data set of known size, and there is one object that I want to test for being in an approximately uniform distributed region of the data set.</p>
<p>For the query object, I know the $k$ nearest neighbors and the associated distances. If the data set is uniform there, the distances should be $c\cdo... | 69,315 |
<p>Repeatedly rolling a six sided die four times and summing the highest three results gives you a distribution with what mean and standard deviation?</p>
<p>I've only taken AP statistics, but I would like to learn how to do this.</p> | 39,934 |
<p>I recently collected some survey data where people made a series of judgments about others' actions and their willingness to make some choice about that action.</p>
<p>Looking at the zero-order correlations, I see that some of the judgments are significantly correlated with the choices of the participant, whereas s... | 69,316 |
<p>We have a multivariate normal vector ${\boldsymbol Y} \sim \mathcal{N}(\boldsymbol\mu, \Sigma)$. Consider partitioning $\boldsymbol\mu$ and ${\boldsymbol Y}$ into
$$\boldsymbol\mu
=
\begin{bmatrix}
\boldsymbol\mu_1 \\
\boldsymbol\mu_2
\end{bmatrix}
$$
$${\boldsymbol Y}=\begin{bmatrix}{\boldsymbol y}_1 \\
{\bolds... | 39,935 |
<p>I am doing research and trying to use a questionnaire that is available in English in another language. </p>
<ol>
<li>Is there a systematic approach for validating a questionnaire in another language? </li>
<li>What statistical test should I be undertake and why?</li>
</ol> | 39,940 |
<p>I am interested in applying Bayesian additive regression trees (BART) for classification analysis of gene expression data. I am relatively new to R (and Bioconductor packages) and I am unable to find some code or vignette that I can use to learn from. I will be thankful if someone can point me in a good direction.</... | 29,747 |
<p>I'm fitting a 4 parameter nonlinear regression model to multiple datasets, some of which fail to converge, however, the parameters output after a failure provide a fit that looks good, if not exceptional to my (and other's) eyes.</p>
<p>I've explored convergence criteria and they do converge eventually but the visu... | 39,941 |
<p><strong>Example of problem:</strong> Part of our research team is working on providing operationally wind power forecast. Usually, since there are different time scalse that interest forecast user, a forecast is issued every 15 min (it has even happened that 5 seconds was requirer) for every 15 minutes ahead up to s... | 69,317 |
<p>Take a look at the image below. Blue line indicates standard normal pdf. The red zone is supposed to be equal to the sum of grey areas (sorry for awful drawing).</p>
<p>I wonder can we create a new distribution with higher peak by shifting grey zones to the top (red zone) of the normal pdf?</p>
<p><img src="http:/... | 32,537 |
<p>As part of the analysis of the data collected from a survey, I was carrying out Kruskal-Wallis Tests between some Likert scale questions and demographics such as firm size and job position. I am using this test instead of One Way Anova since the data is non-normal. </p>
<p>For example, testing the responses of the ... | 69,318 |
<p>I have the following probability model:</p>
<p>$(X_k|\text{PastHistory}_{k-1}, \theta_0,\theta_1,\theta_2) \sim (\pi\cdot N(\theta_1+\theta_0\cdot X_{k-1},1)+(1-\pi)\cdot N(\theta_2+\theta_0\cdot X_{k-1},1))$</p>
<p>and $X_k=0.5X_{k-1}+\epsilon_k$ with $\epsilon_k \sim N(0,1)$</p>
<p>I want to build a function th... | 69,319 |
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