question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>After reading lots of material about the subject, I believe that <strong>the term "stochastic drift" is defined in a two different ways.</strong> These two different definitions make the term unambiguous and I assume that this is the reason you find so many questions regarding unit root testing and ADF. </p>
<p><st... | 29,752 |
<p>I have a number of samples (data points) from two experimental groups, A and B (500 altogether). Each sample corresponds to a large number of variables (genes in my case); together, they form a matrix of $500 \times 40000$. I would like to answer the question, are samples in group A on the general more variable than... | 69,320 |
<p>Please advise good framework for symbolic classification. I am currently using <a href="https://sites.google.com/site/gptips4matlab/" rel="nofollow">GPTIPS</a> for that but I belive there are better options.</p>
<p>What I am trying to do is following:</p>
<ol>
<li>for set of features of my data I am solving standa... | 39,951 |
<p>Every week we have new customers sign up, and some of them submit support requests. I'd like to graph the change in the number of support tickets per customer over time. I'm doing this by bucketing customers into one-week cohorts, and then graphing each distribution as a Tufte box plot, as in this image. The graph I... | 39,952 |
<p>Any hint on this issue would be really welcome: The goal is to employ a two-country comparison analysis. When running two separate OLS regressions, one for each country, the coefficient of variable x is statistically insignificant in country1 regression (Ho:b1=0 is not rejected), while the coefficient of the same va... | 27,779 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/18750/hosmer-lemeshow-vs-aic-logistic-regression">Hosmer-Lemeshow vs AIC: Logistic Regression</a> </p>
</blockquote>
<p>To assess the goodness of fit of a model... is the likelihood ratio test better than ... | 49,827 |
<p>If I have a 1D sequence of complex numbers with real and imaginary parts, how can I compute the histogram of this sequence? Do I separately compute the histogram of both the real and imaginary parts?</p>
<p>Moreover, if I get a 2D histogram of a sequence of complex numbers, how do I apply goodness of fit tests (su... | 39,956 |
<p>In a binomial experiment, if we observe $x=0$ positive individual among $n$ individuals, then the proportion of positive individuals is significantly lower than $3/n$ with a type 1 error less than and very close to $5\%$. This fact, sometimes called the "rule of three", is a consequence of the inequalities $$\exp\le... | 69,321 |
<p>I'm looking for research/white papers on demand estimation for goods/services that are offered on a tiered-basis with varying prices (i.e. more complex the good/service, higher the price.) I'm not sure if this kind of good/service would fall under "bundled goods/services".</p>
<p>A peculiarity of the marketing str... | 69,322 |
<p>I need help with a problem.</p>
<p>Supposed x, y, and z are events in F (algebra of sets) in a probability space (universal set, F (algebra of sets), P). Define two random variables:</p>
<p>a(omega) =</p>
<pre><code> {1 if omega is an element of set X
{0 if omega is not an element of set X
</code></pre>
<p>... | 69,323 |
<p>I am researching the influence of ΔENVIRONMENTAL TAXES+ΔENV.EXPENDITURE =>ΔCO2 EMISSIONS.
and further, the influence of ΔCO2 EMISSIONS =>ΔENV.TAXES after a certain period of time. I have a time series of 16 years for 19 countries.</p>
<p>I have done OLS, FE, RE and Hausman test (to check for endogeneity; and if Hau... | 69,324 |
<p>Is it possible for one-way (with $N>2$ groups, or "levels") ANOVA to give a significant difference when none of the $N(N-1)/2$ pairwise t-tests does? Apparently it is possible, but I do not understand how. When does it happen and what the intuition behind such a case would be? Maybe somebody can provide a simple ... | 29,761 |
<p>I had to translate several given statistics equations into code, and I came across this formula:</p>
<p>Variance of a simple random sample $= \frac{p(1-p)}{n-1}$</p>
<p>The sample in question are test letters sent to measure the efficiency of a postal operator. Each letter has a value of 1 if it's delivered on tim... | 69,325 |
<p>Suppose $X\beta =Y$.</p>
<p>We don't know $Y$ exactly, only its correlation with each predictor, $X^\mathrm{t}Y$.</p>
<p>The ordinary least-squares (OLS) solution is $\beta=(X^\mathrm{t} X)^{-1} X^\mathrm{t}Y$ and there isn't a problem.</p>
<p>But suppose $X^\mathrm{t}X$ is near singular (multicollinearity), and ... | 69,326 |
<p>I have quite a general question about <a href="http://en.wikipedia.org/wiki/Variance-gamma_distribution" rel="nofollow">Variance-gamma distribution</a>. I am interested in how to estimate it's parameters given a set of training points?</p>
<p>I tried to find the answer in the internet, but surprisingly managed to f... | 39,960 |
<p>I´m interested to know if it´s possible (and what it means) to obtain a significant linear model regression (p value=0.008) with coefficients fitted are not significant (p>0.05)? </p> | 49,828 |
<p>Can the chi-squared test be used for comparing survival curves between or among treatment groups? In the particular case of interest, there are 4 treatment groups.</p> | 69,327 |
<p>I'm trying to figure a way of properly displaying the difference\resemblance between various regression values on the same data set, using cox ph, weibull regression and log-normal regression.</p>
<p>Weibull and log normal are similar in their result (predicted values) but cox ph returns the survival function, so I... | 69,328 |
<p>I run multiple variable regression and got the following result. What can i conclude regarding the significance of coefficients? And why?</p>
<p>Thanks</p>
<pre><code>SUMMARY OUTPUT
ANOVA
Coefficients t Stat P-value
Intercept 0.0019... | 69,329 |
<p>I'm fairly new here in this site. </p>
<p>I'm currently taking Bach. Psychology, and Research Methods is one of my core subjects. I have conducted an experiment titled "Gender Differences and Effect of Types of Music on Emotion".</p>
<p>So before presenting the problem I'm having, let me briefly describe my experi... | 69,330 |
<p>I have two variables I want to test with correlation, one is continuous and the other dichotomous. My data are non-normally distributed, plus the variance is heterogeneous, so I have to apply a non-parametric test of correlation. The problem is, I don't know of any test that fits my requirements.</p>
<p>Spearman's ... | 69,331 |
<p>I have the following question to answer:</p>
<blockquote>
<p>The total thickness X of the four pads of 36 half-ring (H-R) mounts
for aircraft engines, taken periodically from the production line,
were found to be as shown below. Determine whether the total number of
runs above and below the median of this s... | 29,769 |
<p>Show that the OLS, MoR and RoM estimators for the
regression of a variable on a constant (ie a variable which always takes the value
one) are all equal to just the mean of that variable. </p> | 69,332 |
<p>I have a dataset with triplets of vectors $\{v_1,v_2,v_3\}_{i=1\dots n}$. Each of them can be understood as a time series (or as a window of a time series). In which way can I give a number "similar" to the covariance of these vectors? I mean, I have a covariance matrix of each of them, and I could get a cross-covar... | 1,142 |
<p>Suppose I have samplings from two distinct populations. If I measure how long it takes each member to do a task, I can easily estimate the mean and variance of each population.</p>
<p>If I now hypothesise a random pairing with one individual from each population, can I estimate the probability that the first is fa... | 69,333 |
<p>A <a href="https://secure.wikimedia.org/wikipedia/en/wiki/Random_forest">random forest</a> is a collection of <a href="http://en.wikipedia.org/wiki/Decision_tree">decision trees</a> formed by randomly selecting only certain features to build each tree with (and sometimes bagging the training data). Apparently they l... | 39,970 |
<p>I am trying to fit this model, but it's giving a warning message I don't understand:</p>
<pre><code>cfit<- coxph(Surv(final$start,final$end,final$event1)~imp+sec+cluster(final$compid))
Warning messages:
1: In fitter(X, Y, strats, offset, init, control, weights = weights, :
Ran out of iterations and did not c... | 69,334 |
<p>I am running lots of simulations in JAGS 3.1.0 , which I have compiled from source. I am using a mid-2009 Macbook Pro 13 2.53GHz.
Is there any step by step tutorial (from scratch) to compile ATLAS or GotoBLAS for JAGS and R (where I use the rjags package)? There are information on ATLAS, GotoBLAS, JAGS, and R compil... | 29,774 |
<p>What assumptions must be fulfilled in quantile regression?</p> | 39,975 |
<p>I have two random variables $X > 0$ and $Y > 0$.</p>
<p>Given that I can estimate $$\text{Cov}(X, Y),$$ how can I estimate $$\text{Cov}(\log(X), \log(Y))?$$</p> | 69,335 |
<p>We are currently doing a research on physiological changes of platelet aggregation during three trimesters of pregnancy and postnatal period, then we compare these groups to each other and the control arm as well. We have recruited 10 patients per each trimester, 10 postnatal and 6 as control arm. The total sample s... | 69,336 |
<p>Is there a way to test linear separability of a two-class dataset in high dimensions? My feature vectors are 40-long.</p>
<p>I know I can always run logistic regression experiments and determine hitrate vs false alarm rate to conclude whether the two classes are linearly separable or not but it would be good to kno... | 29,776 |
<p>Given certain amount of labeled data, we define the net structure, such as number of layers, types of layers, the number of convolutional layers, the number of pooling layers, etc.
And train the parameters using back propagation, meanwhile we show the loss in training procedure and view the testing accuracy in valid... | 69,337 |
<p>I am not a math wizard, so please keep your response simple enough. I need to complete a statistics screening exam for a methods course later on today, and I am hung up on one topic that came up during the practice test. The data set I got was in reference to the number of homicides that have occurred in a number of... | 69,338 |
<p>Assuming normal distribution, one SD is equivalent to an effect size of 1.0, which is associated with a gain of 34 percentage points from the average. From a simple regression model, if past achievement, a score from E to A grade, predicted a change of one SD in current achievement, a standardized score (mean of 0),... | 48,678 |
<p>Trying to fit a model (bloch equations from MRI) to experimental data (12 parameters, 12 equation). Monte Carlo Multistart ('lsqcurvefit' in MATLAB) gives expected values for all parameters except for two, which are correlated: </p>
<p><img src="http://i.stack.imgur.com/Z2Per.jpg" alt="http://imgur.com/1PRayGj"> <... | 69,339 |
<p>I have a process which may be assumed Gaussian - for now I'm assuming it to be zero-mean.
The variance is unknown. </p>
<p>I will estimate variance in the usual unbiased way to give the sample variance and thus the ratio of the sample variance to the true variance follows the Chi Squared distribution.</p>
<p>In pa... | 69,340 |
<p><strong>Question:</strong></p>
<blockquote>
<p>A single-pump petrol station is running low on petrol. The total
volume of petrol remaining for sale is $100$ litres. </p>
<p>Suppose cars arrive to the station according to a Poisson process with
rate $\lambda$, and that each car fills independently of all ... | 69,341 |
<p>I am trying to determine the fit between two curves (example shown below). Both curves are plotted here as a bunch of XY data points (not functions).</p>
<p>The curves represent the trajectories of two planes taxiing, and I'm trying to figure out how far apart they are on average. (axes are in x/y position in meter... | 39,984 |
<p>This is a question posed by NASA astrobiologist Chris McKay (who wants to put life together back from its pieces), who really wants an answer to this question since it could lead us to reconstruct ancient genomes that are billions of years old (but mutated through years of internal radioactivity)</p>
<ul>
<li><p>A ... | 29,782 |
<p>I want to use linear mixed effect model for a set of data.</p>
<p>After using <a href="http://cran.r-project.org/web/packages/lme4/" rel="nofollow">lme4</a> package and <code>lmer()</code> function and fitting model, I want to validate my model for other period time. But I don't know how to validate my model and ge... | 30,119 |
<p>I want to use body measurements to predict body weight in broiler chickens. There were seven body parameters measured. I did a principal components analysis and three components were extracted after varimax rotation. How do I use these components as independent variables to predict body weight (the dependent variabl... | 69,342 |
<p>Roughly speaking a p-value gives a probability of the observed outcome of an experiment given the hypothesis (model). Having this probability (p-value) we want to judge our hypothesis (how likely it is). But wouldn't it be more natural to calculate the probability of the hypothesis given the observed outcome?</p>
<... | 29,785 |
<p>I'm going to analyse suicide rates for a time series, and I'd like to use robust tests, but I don't know which would be a good one. My purpose is to compare the variation of the suicide rates through the months and years and see if there are significant changes in respect to GDP. Then I also want to check difference... | 17,899 |
<p>For 2 variables to be independent of each other, should the correlation = 0 or mutual information = 0 or covariance = 0. I have seen different conditions and all these are really confusing.</p> | 30,120 |
<p>As a biologist, many of the research projects I work on at some point involve collaboration with a statistician, whether it be for simple advice or for implementing and testing a model for my data. My statistics colleagues admit that they do a significant amount of collaboration, insomuch that the tenure review proc... | 29,787 |
<p>I'm analyzing some data from an experiment. There is one response variable (response) and 3 factor variables, each with 2 levels (profile, drug, disease). I want compare specific combinations of (profile, drug,disease), e.g. (profile 1, drug 1, no disease) vs. (profile 1, drug 2, no disease). I've been approachin... | 69,343 |
<p>This problem has perplexed me for a long time, and I would love to learn how to solve it.</p>
<ol>
<li><p>Each parent contributes, on average, half of the genetic material of each child. If a parent has $n$ children, what percentage of the parent’s genes exist in total across all $n$ offspring?</p></li>
<li><p>How ... | 69,344 |
<p>I'm generating predicted probabilities (propensity scores) in Stata using the predict command. The basic structure of my code looks like this:</p>
<pre><code>logit depvar indepvars
predict ps // Gives Pr(depvar = 1 | indepvars)
predict s, stdp // Gives the standard error of the prediction
</c... | 69,345 |
<p>Suppose I have 50 scale parameters, these are all genes measured for one sample from a subject at the clinic, after data reduction by PCA, two meaningful components were extracted. This was followed by cluster analysis and turned out to be 4 meaningful clusters of subjects based on the two components of these 50 gen... | 69,346 |
<p>I am learning some model based on examples ${((x_{i1},x_{i2},....,x_{ip}),y_i)}_{i=1...N}$ using a neural network of Feed Forward Multilayer Perceptron (newff) (using python library neurolab). I expect the output of the NN to be positive for any further simulation of the NN.
How can I make sure that the results of ... | 69,347 |
<p>I have a set of data consisting of measurements in ten subjects of the same physiological parameters. The measurement and processing of the data have been carried out at two sites, A and B. For each measure and each subject, I thus have four versions of the same parameter:</p>
<p>Measured at A, processed at A (AA);... | 29,790 |
<p>I am looking to determine the effect the Liquidity Coverage Ratio (From Basel III) may have towards the issues of systemic risk or on bank lending rates.</p>
<p>How would I go about doing a regression analysis for this?</p>
<p>Thanks!</p>
<p>Please help if you can :)</p> | 69,348 |
<p>I already wrote a similar question on StackOverflow but was not welcomed there! So I decided to ask it from the folks here.
I have wrote a code in Python for CRP problem. I think everybody here is familar with the subject but nevertheless:</p>
<p>Short description of it:
Suppose we want to assign people entering to... | 69,349 |
<p>Grid search suffers from the curse of dimensionality. But is there any case(any hypothetical distribution of data) in a two dimensional feature space where the data’s binary classification using Grid Search would yield very poor results? </p> | 69,350 |
<p>I'd like to know whether starting from a beta distribution and iterating it in the way described below, I will get a stationary (beta) distribution again.</p>
<p>More specifically this is the problem I am facing:</p>
<p>Starting with a $\mathrm{Beta}(2,1.5)$, for each element $\phi$ drawn from this pdf, draw from ... | 29,794 |
<p>This is a follow-up question to this one: <a href="http://stats.stackexchange.com/questions/74818">Significance test across multiple simulated experiments</a>
There's one answer I'm leaning towards accepting, but I wanted to make sure I understood how significance can be calculated across multiple experiments OR est... | 69,351 |
<p>Let's say I'm doing some predictive analytics and am trying to predict US GDP per month using a two or three month lag. After every month, I generate new predictions and am able to compare my prediction to the actual gap. What would be the best way to represent this via plot. Line chart?</p>
<p>In all the research ... | 69,352 |
<p>What are the assumptions of the Games-Howell multiple comparisons procedure? Please back up any answers with references.</p> | 48,808 |
<p>This might be a question for the programmers, but I thought I would ask here first. Im comparing browsing pressure on plants between sites. Ive a value to indicate Browsing Pressure and count data of trees that have been damaged between locations. Ive been using Crawleys R example (page 574) regarding sex ratios ... | 69,353 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/37399/weighted-geometric-mean-vs-weighted-mean">Weighted geometric mean vs Weighted mean</a> </p>
</blockquote>
<p>I searched for the differences between WHM and WGM.
When to use each of them? when not?</p... | 49,829 |
<p>I would like to perform a PCA and use the covariance matrix obtained by the <a href="http://www.math.nyu.edu/fellows_fin_math/gatheral/RandomMatrixCovariance2008.pdf" rel="nofollow">random matrix theory</a>.</p>
<p>Is there an implementation of this in R?</p>
<p>I am currently using the standard <em>prcomp</em> fu... | 29,798 |
<p>I am trying to model a linear regression to predict the number of interested students in a class based on a couple of properties of that class- </p>
<ol>
<li>whether that class has an undergraduate curriculum (assigned 0 or 1)</li>
<li>whether that class has mandatory homework (assigned 0 or 1)</li>
<li>whether tha... | 69,354 |
<p>In my study, the variables are cointegrated. Now I want to test causality so should I perform VAR, VECM or the Granger causality test?</p> | 69,355 |
<p>Software packages for network motif detection can return enormously high Z-scores (the highest I've seen is 600,000+, but Z-scores of more than 100 are quite common). I plan to show that these Z-scores are bogus.</p>
<p>Huge Z-scores correspond to extremely low associated probabilities. The values of the associat... | 69,356 |
<p>When comparing a regression estimation method (Y vs X) I currently use a weighted squared loss function:</p>
<p>$$
\int_{-\infty}^{\infty}(\hat{f}(x)-f(x))^2 \, \hat{p}(x) \, dx
$$</p>
<p>Where $\hat{f}(x)$ is the estimated function, $f(x)$ is an estimation method I'm comparing against, and $\hat{p}(x)$ is t... | 40,003 |
<p>I don't know if this is the right StackExchange for this question, but I am using Ubuntu 12.04 and I am trying to install R, but all the guides I get are really painful and involve long and complicated descriptions of guides I can't find my way around in. Does anyone know an easy guide to install R that I can just f... | 29,802 |
<p>Today I opened two STATA windows and ran the following command in both:</p>
<pre><code>set obs 100
gen x = rnormal()
sort x
</code></pre>
<p>(the difference is that on the second window I generated a variable called y). Summing up: I asked STATA to give me 100 pseudo-random numbers taken from a standard normal di... | 40,005 |
<p>Hi
I am using Linear and exponential forecasting models to do sales forecasting. In the model itself, we use the forecasts of period t to get next forecast and so on.
While analyzing the accuracy of the forecast using Mean Absolute Percentage Error, I get good results. But when I compare the intermediate forecast va... | 69,357 |
<p>Hello
I am trying to forecast using different exponential smoothing methods(Linear and Winter's). For the optimal parameters, I am getting negative values of the forecasats.
I am assuming it means that the values will be zero, since it is a sales forecast.
I wanted to know if negative values denote something wrong... | 69,358 |
<p>I have 4 files, each containing the observations for a different plant. The observations are the probability of occurrence of a particular "event" over many intervals over the plant's genome.
That is, the observation file looks like this:</p>
<pre><code>file/plant 1:
ch01:a1-b1
p = 0.41
ch01:a2-b2
p = 0.005... | 69,359 |
<p>I am looking at equation (2.16) from <a href="http://www.stanford.edu/~hastie/local.ftp/Springer/OLD/ESLII_print4.pdf" rel="nofollow">Elements of Statistical Learning</a> and can't seem to be able to derive it. I used $f(x) = x^T\beta$ as the linear model, and tried calculating $\beta$ by minimizing the expected pre... | 69,360 |
<p>I have written 3way-anova in c++. I have 3 factors, lets say a,b and c and my aim to check the strength of all possible interactions and main effects.The result of my code is the same as MATLAB when I use type I sum of squares.<br>
But when I change the data so that the number of replicates is so high in some cells ... | 69,361 |
<p>Problem is that government wants to close electronic roulette and they claim that roulette failed at statistical test.</p>
<p>Sorry for my language but this is translated from Slovenian law as good as possible
Official (by law) requirements are:</p>
<ul>
<li>frequency of each event should not differ from expected ... | 29,804 |
<p>I was reading this paper:</p>
<blockquote>
<p>Ristovski, K., Das, D., Ouzienko, V., Guo, Y., Obradovic, Z.
<a href="http://www.ist.temple.edu/~zoran/papers/ristovski_ECAI2010.pdf" rel="nofollow">Regression Learning with Multiple Noisy
Oracles</a>.</p>
</blockquote>
<p>This paper is basically about regressio... | 69,362 |
<p>I have the following problem:</p>
<p>If $X$ satisfies a binomial distribution with parameters $n$ and $p$, its expected value is $np$ and variance is $np(1-p)$. Prove these using formulas given in pages 8 and 10.</p>
<p>On page 8 we have been given that </p>
<p>$E(X)=\sum_{i=1}^k P(X=x_i)x_i$, </p>
<p>$\operator... | 29,806 |
<p>This is the logistic distribution of single random variable (taken from Wikipedia).</p>
<p>$x$ = random variable
$\mu$ = mean of all random variables
$s$ = variance.</p>
<p><img src="http://i.stack.imgur.com/qUHkD.png" alt="enter image description here"></p>
<p>Now, I want to do a Bivariate logistic distribution ... | 69,363 |
<p>There is a problem posted back in 2009 that I found that has me puzzled. I believe the estimates are from a generalized linear regression because after some thought it seems $X'X$ is impossible to obtain from the given info. So it must be something to do with the Cholesky decomposition of $\Sigma$, but I do not se... | 69,364 |
<p>I have a large gridded dataset for the globe (i.e a spherical, wraparound surface) that I'm applying spatial regression to (using a CAR model). I've been using the default autocorrelation function, however as my data is global (point 0,0 lies next to max(x),0 and 0,max(y)), I wondered if a spherical autocorrelation ... | 40,006 |
<p>I have run a 1 way ANOVA and carried out some post hocs to see which direction the results go in. If I report the direction of the findings - e.g. this group was higher than the other, which statistic do I quote? I have carried out Games-Howell post hoc and all it seems to come with is an associated p value, is this... | 69,365 |
<p>I am trying to draw random numbers that follow a two-part pdf</p>
<p>a) $|x|< x_0: f(x)=\text{constant}\quad \to \quad F(p)=a+(b-a)p$</p>
<p>b) $|x|> x_0: f(x)=\exp(-|x|)\quad \to \quad F(p)=-\ln(1-p)$</p>
<p>that is the probability is constant between $(-x_0,x_0)$ and falls exponentially outside it.</p>
<... | 69,366 |
<p>I need two sets of data collected over 3 years. The first data has 12 waves where each wave represents a quarter. The other has 24 waves where each wave include some part of the previous wave (e.g. 1st wave 1/1/07-4/30/07; 2nd wave 3/1/07-6/30/07 ...)</p>
<p>The variables measured were rates (specific lab tests tak... | 29,809 |
<p>I have trained my random forest model on a 74,000 training examples where each example consists of two proteins Amino Acids sequence (20 characters) and some numeric values representing the similarity between each individual pair of sequences, and finally a numeric value representing the overall similarity between t... | 69,367 |
<p>I.e. I want to put in Baseball and get out Sports & Outdoors. </p> | 40,011 |
<p>I am using <strong>real data</strong> for a comparison of two groups: there are 3 replicates in one group and 3 replicates in the other group. All 6 replicates come from the control group, so that their responses should, ideally, be very similar, and a test should report very few significant results.</p>
<p>Now I g... | 69,368 |
<p>I have to separate two populations by a line in a scatterplot:</p>
<p><img src="http://i.stack.imgur.com/B7NpS.png" alt="Dot plot"></p>
<p>I would like find a threshold that separates the two populations. In @Waynes words, I would like to cluster the points into two categories, then calculate the line which best s... | 69,369 |
<h1>Premises</h1>
<p>I'm training a <em>convolutional neural network</em> (ConvNet) on 51 subclasses in the <a href="http://www.image-net.org/" rel="nofollow"><em>ImageNet</em> dataset</a>. In order to keep an eye on <em>overfitting</em>, I have been suggested to plot training and testing <strong>loss function</strong... | 69,370 |
<p>I am comparing various GLMs fit to a series of data (loss development actuarial triangles) and I am wondering how to rank Over Dispersed Poisson Models (ODP) against other GLMs (e.g. Negative Binomial or Gamma Glms) since AIC is not defined for ODP and I'm not sure deviances are comparable.</p> | 69,371 |
<p>Stats noob here working on an algorithm for ranking players in a tournament.</p>
<p>I have a test set of players, each with a "skill" value. My algorithm simulates a "tournament", in which players play against each other (1v1) in some order (e.g. Swiss pairing). At the end of the tournament, I have each player's ... | 69,372 |
<p>I have to run an analysis using different steps, to include first the control variables, second the independent variables, and finally the interaction terms (moderation). However, I don't know if I should use hierarchical regression or stepwise.</p>
<p>Could anyone explain me what are the differences between both m... | 29,815 |
<p>In SPSS, the user can check the relative variable importance in a clustering result and produce a graph like the following: </p>
<p><img src="http://i.stack.imgur.com/f4UUd.png" alt="enter image description here"></p>
<p>link:
<a href="http://pic.dhe.ibm.com/infocenter/spssstat/v20r0m0/index.jsp?topic=%2Fcom.ibm.s... | 69,373 |
<p>I am doing some experiments with Markov Chain models and want to know whether there is a standard representation for such models on disk in academia/industry? I want to avoid re-inventing the wheel with regards to parsing this data. Hopefully I can also validate my implementation against other implementations for th... | 69,374 |
<p>This question comes from:</p>
<p><a href="http://stats.stackexchange.com/questions/64433/how-to-simulate-a-cox-proportional-hazards-model-with-change-point-and-code-it-i">How to simulate a Cox proportional hazards model with change point and code it in R</a> (See answer)</p>
<p>I want to generate a censoring varia... | 29,818 |
<p>I am assessing the presence or absence of a number of developmental milestones in mice in their first $21$ days of life. Each day, from the day they are born until they have $21$ days, I test if pups have or not specific developmental milestone. This analysis involves $2$ groups, a control and an experimental.</p>
... | 29,819 |
<p>I am writing a master's thesis on crowdfunding. For this research I set N independent variables and 3 DVs. The reason for doing so is that I want to explore the phenomenon from the aspects of all 3 DVs, as they are giving me different insights, and to crosscheck the results from all 3 models. Here is a bit more deta... | 29,820 |
<p>I'm trying to get intuition for each of the main functions in actuarial science (specifically for the Cox Proportional Hazards Model). Here's what I have so far:</p>
<ul>
<li>$f(x)$: starting at the start time, the probability distribution of when you will die.</li>
<li>$F(x)$: just the cumulative distribution. A... | 29,821 |
<p>I did some experiment in which tests are taken twice, pretest and posttest. I found there might be ceiling effect because the average of posttest is close to maximum test score possible. If I assume an IRT model: as the ability is getting higher (above difficulty level of the problems), the expected score distribu... | 29,822 |
<p>I randomized my survey, and now I have my data on SPSS (and all cleaned up) but when trying to run my Cronbach's alpha I have a problem.</p>
<p>Because I have two treatments (sexualised and normal) all my measures are present twice in my data set. For example, “similarity” has 3 items but now I have 6 variables: 3 ... | 29,823 |
<p>I have a range of readings from a test (for example:0.796, 0.109, 0.11, 0.11, 0.109, 0.109, 0.109, 1.78). I want to remove the extraneous values of these so that I get a more realistic view on the more accurate test result range. If I take the average (1.78) or the median (1.09) it doesn't give me that picture. I am... | 69,375 |
<p>In a number of singular value decomposition (SVD) applications, for example Latent Semantic Indexing, only the biggest singular values are used to make searches and calculate distances.</p>
<p>Are there useful applications that drop the biggest singular values and use only the smallest ones? </p> | 69,376 |
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