question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Lets say I have a table with columns "A", "B"</p>
<p>Is there a statistical method to determine if "A" causes "B" to happen? One can't really use Pearson's r, because:</p>
<ul>
<li>it only tests the correlation between values</li>
<li>correlation is not causation </li>
<li>Pearson's r can only correlate linear re... | g46728 | [
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<p>I am working on developing a logistic regression model that uses qualitative variables only ($n=990$). My remit is to define the equation that can identify the most relevant characteristics of a survey respondent that is favorable towards Company X. The proposed equation is similar to the following:
\begin{align}
{\... | g23441 | [
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<p>I have a dataset spanning several years, that I have analysed year by year (using the same glmm model code) to determine whether the random effect (random intercept) has altered over time. I have found that it has altered. Now I am concerned that the fixed effects have also altered, which may mean that I can't compa... | g23442 | [
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<p>This is more of a data management question.</p>
<p>When merging several waves of a survey where the same questions were asked in multiple years -- but each time of a new sample -- should the data from a question be merged into the same variable or separate variables?</p>
<p>Since each wave was administered to a ne... | g43286 | [
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<p>I'm fairly well acquainted with using <a href="http://en.wikipedia.org/wiki/Reservoir_sampling" rel="nofollow">Reservoir Sampling</a> to sample from a set of undetermined length in a single pass over the data. One limitation of this approach, in my mind, is that it still requires a pass over the entire data set befo... | g65038 | [
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<p>So, I'm working with GWAS SNP data and want to perform several tests for association between genotype and phenotype. There are two phenotypes (case and control) and 2 or three genotypes. Most of them are Chi-squared tests with different contingency tables, $2 \times 2$ or $2 \times 3$, one of them is the Cochran-Arm... | g65039 | [
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<p>Under the null, the p-value is uniformly distributed between 0 and 1. Taking the negative of the log base 10 of many such p-values should follow an exponential distribution. You can show quantiles of their distribution under the null, but more importantly, logging them makes large differences very compelling. I can'... | g26106 | [
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<p>I have a so so sized data set - 30 000 observations. I would like to run K-means on them but to restrict the center(mean) of the data. This is, I would like to push the clusters away from this mean. As I have noticed that independantly of the # of clusters, one ends up landing right on top of the mean of all the var... | g23448 | [
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<p>I'm trying to approach the following problem: Danny & Johnny are professional basketball players. Each day they meet, and play for a while. Whoever scores the most points is declared winner for the day, and wins a dollar. After a year of games, we are given a vector (including 365 elements) representing, say, Da... | g65040 | [
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<p>Sorry for the (most likely) simple question, but I have Box Cox transformed my data in SAS, but I am unsure how to use the transformed data in my mixed model. Do I output it to a new file, and use that in my model statement, or do I need to incorporate the proc transreg statement into my proc mixed? Details are ap... | g65041 | [
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<p>In one of the paper I am writing, I am looking at cross-validation on bootstrap samples. I wrote the following explanation.One of the reviewer wrote that he didn't understand where is the correlation. I don't know how to explain better. So I was wondering if someone has a reference I could cite about this issue when... | g65042 | [
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<p>This is a problem of classification. If I have 100 training data of category A and there are some features in A. Suppose feature 1 always shows up with category A. But there is only one training data for category B, with feature 2 in it. We also have many data for category C. Feature 1 and feature 2 never show up in... | g23453 | [
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<p>Addition, subtraction, multiplication and division of normal random variables are well defined, but what about trigonometric operations?</p>
<p>For instance, let us suppose that I'm trying to find the angle of a triangular wedge (modelled as a right-angle triangle) with the two catheti having dimensions $d_1$ and ... | g49835 | [
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<p>I have data that have been collected using case-control procedures, in which the population of positive cases is collected with a random sample of negative cases. This yields 62 positive cases and 179 controls. There are 58 possible predictor variables (mostly numeric, two factors).</p>
<p>My goal is not classifica... | g23455 | [
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<p>I'm trying to write an R script to simulate the repeated experiments interpretation of a 95% confidence interval. I've found that it overestimates the proportion of times in which the true population value of a proportion is contained within the sample's 95% CI. Not a big difference - about 96% vs 95% but this inte... | g43294 | [
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<p>I created a poll on a sports forum asking people how they think their favorite NBA team did this off-season. The poll options were: Top 10, Middle 10, Bottom 10. I expect dozens of people to respond, which isn't a huge sample.</p>
<p>The hypothesis I'm testing (unbeknownst to the voters) is that there will be a "ho... | g65043 | [
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<p>This is my first question on stackexchange and also my first time implementing a Bayesian network so I will apologize ahead of time for any novice mistakes I make.</p>
<p>The goal of my project is to implement a Poker player that does Bayesian inference. There has been some work done on this by a group at Monash Un... | g65044 | [
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<p>A response variable y is a nonlinear function of a number of predictor variables X (in my real data the response is binomially distributed, but here I'm using a normally-distributed value for simplicity). I can model the relationships between the predictors and the response using splines / smooths (for example, GAM ... | g43300 | [
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<p>I have 2 sets of brand preference data (in %) to measure impact of online advertising on target group F20-40 years i.e., 1.different time period (pre/post - not same consumers but same target group) & 2. Control (not seen online advertising) vs Exposed (exposed to advertising). Could you suggest what statistica... | g40913 | [
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<p>I had asked a general question about conditional inference trees via party a while <a href="http://stats.stackexchange.com/questions/12140/conditional-inference-trees-vs-traditional-decision-trees">back</a> and gotten a great reply.</p>
<p>I am revisiting this procedure and trying to make sense of the linear statis... | g43302 | [
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<p>I have some models built with the <code>auto.arima</code> function from the <code>forecast</code> package. I'm modeling a variable called 'natural efluent energy' (ena), which is how much energy you can extract from some Hydrography region. There are 2 regressor variables (rainfall precipitation from period $t$ and ... | g46575 | [
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<p>I intend to use factor scores as derived from exploratory factor analysis in subsequent multivariate regression analysis, as an explanatory variable.</p>
<p>I've read in multiple books/papers that Structural Equation Modeling is the appropriate method to model relationships AMONG LATENT VARIABLES (using factor scor... | g49552 | [
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<p>I intend to do an exploratory factor analysis among items that have different types of measurements: for example, some items have bounded scales (1-100%), some items take small and other large values (different units indeed, such as dollars or hours).</p>
<p>I've been reading a lot and haven't found a negative answ... | g65045 | [
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<p>I am using stochastic gradient descent to learn a model. Here is the plot of the objective function for the iterations. I am trying to maximize the function value.</p>
<p><img src="http://i.stack.imgur.com/3Eq3T.jpg" alt="enter image description here"></p>
<p>Taking the average of 500 iterations, I have this next ... | g23461 | [
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<p>In case of <em>caret</em> package test function metric option, one can use either accuracy or ROC as a metric that will be used to finalize values of tuning parameters. I felt that accuracy and ROC are the same</p>
<p>Accuracy = total correct predictions/total samples</p>
<p>ROC= looks at various probability cutof... | g65046 | [
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<p>I'm using G*Power to work out how many participants I need. I'll be using a MANOVA, I have two independent variables (Male and Female) and they will be answering 13 different questionnaires so 13 dependent variables.
I put this data into G*Power and its telling me I only need 14 participants but I think that is too... | g65047 | [
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<p>I have to regress the mortality rate which is in number of deaths per thousand and percentage of vaccinated people. Have sample data for different districts. Can I use linear regression directly. The sample sizes are different for different districts. Please suggest the appropriate method. </p> | g65048 | [
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<p>In a manufacturing program I am collecting the estimated time required and the actual time taken for a series of tasks.</p>
<p>Suppose I find that I often take twice as long, say, as I originally estimated for each task, I want to apply a typical difference between estimated and actual time taken to future planned ... | g65049 | [
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<p>In designing a email test, I have three binary factors (each have two levels, say low-high). Our customers are divided into 5 non-overlapping groups.</p>
<p>Is it best to run a randomized block design, blocking out the customer groups (5 blocks, 2^3 factorial) or use the customer groups as an actual 5-level factor?... | g65050 | [
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<p>I have built a cox proportional hazards model in the R survival package. I want to score new data set using this model. I thought the survfit function would doing this using survfit(original model, newdata), but it only seems to predict only the outcomes for the original data, not the original model using the new ... | g65051 | [
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<p>I want to determine a number of clusters, but I don't know how to do it. I want to use kmeans and select a number of cluster with minimum variance or with a maximum jump in variance. I plot variance; how can I do it with programming (Java)?</p> | g65052 | [
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<p>I am fitting a series of Bayesian spatial models with an intrinsic conditional autoregressive (iCAR) structure. In these models, I begin by fitting an empty model (null) and then add successive sets of covariates based on a conceptual foundation.</p>
<p>I then map quantiles of the mean posterior spatial random effe... | g4888 | [
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0.01788865402340889,
-0.023059608414769173,
0.021797385066747665,
-0.01987413503229618,
0.05789869651198387,
0.034585... |
<p>I am thinking about a problem which is to predict log(spend) of a customer using linear regression.</p>
<p>I am considering what features to use as input and wondering if it would be OK to use the percentile of a variable as inputs.</p>
<p>For example I could use the companies revenue as a input. What I'm wonderin... | g446 | [
0.006459525786340237,
0.000704165839124471,
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0.021081333979964256,
0.05725196376442909,
0.02155090495944023,
0.04862673208117485,
0.006... |
<p>I am wondering somebody here may provide a formula or source for calculating Wilson score confidence interval of difference of two proportions (namely CI for p1-p2). It seems most available web sources are for one sample proportion. Thanks in advance</p> | g49716 | [
0.03404468670487404,
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0.007399674039334059,
0.013502848334610462,
0.007412631995975971,
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<p>I have been asked whether there is any relationship between two variables $X$ and $Y$. I have done a simple regression and the confidence intervals suggest a small significant relationship. However, these variables are nonnegative and most of the points are "close" to (0,0) --- in the sense that in a graph of the po... | g65053 | [
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0.03422241285443306,
0.02898421511054039,
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0.034653... |
<p>If I have the following contingency table in which <code>Novel.Cat</code> is a new means of classifying some thing. <code>Ref.Cat</code> is the gold standard. How can I do some sort of test to see whether the two means of classification generate significantly different results? Is just a simple Fisher's test appropr... | g43338 | [
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0.07233971357345581,
0.027558404952287674,
... |
<p>I am training a Gaussian process with an ARD kernel with lots of parameters by maximizing the marginal lielihood of the data, instead of cross-validation. </p>
<p>I suspect that it is over-fitting. How can I test this suspicion in a Bayesian context?</p> | g23474 | [
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0.030424855649471283,
0.02242247574031353,
0.04123345762491226,
0.02228263020515442,
0.0502... |
<p>Consider the following code/output:</p>
<pre><code> library(ordinal)
clm(as.factor(y)~x, link="probit", data=data)
0|1 1|2 2|3 x
59.5369 90.9923 112.1025 138.1162
data
x y
1 0
2 0
3 1
4 1
5 2
6 2... | g65054 | [
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0.016678322106599808,
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0.04803456366062164,
0.02570304647088051,
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-0.05766904354095459,
0.05991725996136665,
0.015145129524171352,
0.0016... |
<p>Are Probability Graphic Models (say specifically Bayesian Networks) useful for predictive modelling in terms of large data (100,000 - 1,000,000 rows) and many variables (hundreds)? </p>
<p>Meaning, is this technique / methodology something that can be a competitor for, say random forests or some machine learning me... | g65055 | [
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0.017900386825203896,
0.014326825737953186,
-0.04079270735383034,
0.05039654299616814,
-0.012402010150253773,
0.09781353920698166,
0.01... |
<p>In a multiple logistic regression I need to standardize one of the variables because I need to add a quadratic term. Whether I add the quadratic term as the squared original or the squared standardized, I get very similar models, same AIC. Why? The estimates of the linear term change.
When I square a standardized v... | g23475 | [
0.033918045461177826,
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0.015158618800342083,
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<p>I have a table of <code>mRNA</code> levels of my target gene and it's transcription factors in many different condition. What I want to do is to select the most important conditions and most important transcriptional factors. I used <code>glm</code> in <code>R</code> but I am stuck at the point that I can't extract ... | g65056 | [
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0.019884571433067322,
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<p>I am looking at some software code that performs conditioning on random variables. For example, one can have a set of random variables which have a multivariate normal distribution associated with them and then you can condition on a given variable to take on a certain value and then get the associated conditional d... | g65057 | [
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0.050048235803842545,
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0.030689872801303864,
0.... |
<p>I'm trying to illustrate the CLT with scilab but my results are weird.</p>
<p>Did I make a mistake ?</p>
<pre><code>function res = simul_ber(m,n,p)
// creates a vector simulating a binominal law with parameters n p
res = grand(1,m,"bin",n,p)
endfunction
function clt_binom(m,n,p)
clf()
v = ones([1:m])
histplot(flo... | g65058 | [
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0.042666830122470856,
0.008736818097531796,
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<p>I have 31 numeric variables (e.g., A-AF) for which I am attempting to identify the smallest subset of those variables that will predict the values of the remainder of the variables with a CI of 90% or greater.</p>
<p>For example, I would like end up with a model in which the values of variables A, B, C, D, and E, t... | g23477 | [
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0.016... |
<p>First post here; first I would like to say that I have no background in stats whatsoever and not so much in math either (enriched high school math, and that's it).</p>
<p>I started an MA and we have to do a meta-analysis; we've also been reading a lot of publications with effect sizes. </p>
<p>I checked Wikipedia'... | g23478 | [
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0.02433449774980545,
0.09079621732234955,
0.03... |
<p>On the back of an earlier question i am having an issue.</p>
<p>Software = SAS JMP Pro 11</p>
<p><a href="http://stats.stackexchange.com/questions/88573/can-i-use-rotated-pca-factors-to-make-models-and-then-subsitute-these-back-to-my">Earlier Question</a></p>
<p>My rotated factors (post Principal Components Analy... | g65059 | [
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<p>How can a probability distribution P not factorize over a graph H when P satisfies the all the global independencies implied by H?</p>
<p>Here's an example: Let $X_1, \dots X_4$ be 4 random variables that can take on 0 or 1. The graph $H$, is a circle: $X_1 \rightarrow X_2 \rightarrow X_3 \rightarrow X_4 \rightarro... | g65060 | [
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0.05307580158114433,
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0.002712187822908163,
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0.008384735323488712,
... |
<p>I have performed a clustering on 20K genes, and I want to understand how coherent resulting clusters are by calculating the significance of the overlap of the clusters with a number of known GO gene categories. I use hypergeometric p-values for this purpose, and I also want to correct for multiple testing using Bonf... | g65061 | [
0.02622796781361103,
0.05077163875102997,
0.006056807469576597,
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0.028604133054614067,
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0.05035999417304993,
0.0806291252374649,
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0.03715169057250023,
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0.01196306198835373,
0.03776589408516884,
0.05002178624... |
<p>i have a fitted a classical Poisson regression model to my 584 claim frequency data set for a period of 5 years (panel data)i have found out that predictors area,age and make of vehicle are siginificant (preferred model).Other predictors are age and gender of insured and cc of car. Now i want to fit a Poisson rando... | g23482 | [
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0.018131868913769722,
0.019991662353277206,
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... |
<p>The term forward model comes up a lot when reading about Bayesian modelling. I am yet to understand what exactly is the forward model? Is it the model that describes the output/observed variable and the inverse model is that given the observation, what is the underlying model that explains this observation?</p> | g65062 | [
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<p>I work out the conditional variance using a GARCH model based on daily returns as follows:</p>
<pre><code> conditional variance
1/1 0.024879711
2/1 0.02607681
3/1 0.026476405
4/1 0.025159491
5/1 0.023916521
.
.
.
31/1 0.022825... | g65063 | [
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0.04126599431037903,
0.008812244981527328,
0.042895738035440445,
-... |
<p>I want to understand if an experiment gives equal response at two different levels of an experimental parameter. What I did was to repeat the experiment 6 times at the first level of the parameter and 6 times at the second level. The problem is that the experiment measures 20 variables, so I have 12 experiments and ... | g523 | [
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<p>I am reading a book on time series analysis and I am having problems understanding the section about outlier detection.</p>
<p>The authors say that when you want to know whether at a certain time $T$ there was an outlier, you should use a certain test statistic and a test with size less than $\alpha$. But when you ... | g23484 | [
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<p>I am planning to develop a course which I tentatively call as 'Quantitative Reasoning'. The goal of the course is to equip a typical undergraduate student with sound quantitative reasoning skills so that they can critically evaluate statistical and related quantitative claims they may encounter as part of their pers... | g65064 | [
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<p>The motivation for this question is from Finance. I have some market data (daily time series) for the price of some securities and I would like to generate synthetic versions of these which are statistically "similar" (in some sense) for testing trading strategies. Is there literature on this subject?</p>
<p>I was ... | g23486 | [
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0.005885015241801739,
0.015622620470821857,
0.053456466645002365,
... |
<p>I'm working on a machine learning algorithm and have gotten stuck with how to rebalance a discrete probability distribution. I have a distribution represented as a simple array of $n$ numbers which are all bounded between $0$ to $1$ and that always sum to $1$. At a particular point I wish to update on of the numbers... | g23487 | [
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0.01863333210349083,
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0.026461781933903694,
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... |
<p>This post pertains to Bayesian pdf manipulation.</p>
<ul>
<li>Firstly, assuming a prior probability specified as <em>Gamma</em> distribution such that $\alpha = \mu_{0}^{2}/\sigma_{0}^{2}$ and $\beta = \mu_{0}/\sigma_{0}^{2}$; is it correct to assume, substituting into the Gamma distribution, that the prior has the... | g43350 | [
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0.06860488653182983,
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0.021475089713931084,
0.014708067290484905,
0.020747851580381393,
-0.0034803978633135557,
... |
<p>I have data on birth intervals of women. Birth interval refers to the time interval from one child's birth date until the next child's birth date. Here, dependent variable is the birth interval, defined as the length of time between two successive births for different parities, which are measured in single months. H... | g23489 | [
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0.0624513104557991,
0... |
<p>I'm using hidden Markov models to classify some accelerometer data. I take the Fourier transform of the raw data at a given window length, and then train an HMM for each class, and every test instance is classified as the class corresponding with the HMM giving the highest log likelihood.</p>
<p>Now, I want to try ... | g65065 | [
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0.024305958300828934,
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<p>I am novice in Stats.
I drew 5 numbers from 5 Odd and 4 Even numbers.
After 10,000 runs, what will be statistical model look like; will be sure the ratio for odd to Even will end in ratio 3:2 ?
If the same model is made for 5 numbers consisting 3 Odd and 2 Even and 3 numbers are drawn will it also end in 2:1 ratio?<... | g23491 | [
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0.047193001955747604,
-... |
<p>I have read a number of articles that talk about companies such as Google, Facebook, and many others using R for research. The other scenario I have read about is companies using R to prototype an analytics solution and then re-implement it in another language.</p>
<p>I am trying to find literature on companies usi... | g46887 | [
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0.06558820605278015,
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0.045225296169519424,
0... |
<p>So, I struggle with Regression a lot. I just found out how to get 2 lines with the same slope, but I cannot manage to get 2 lines with the same intercept. I read about ANCOVA a lot (because I thought this was what I needed), but no one uses the same intercepts; just the same slope.
Can someone help out with this?</p... | g43354 | [
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0.00897408276796341,
0.045420486479997635,
-0.00... |
<p>I have code that generates a random permutation. In my case, a permutation consists of N binary features, and each of the N features is set or unset randomly. How many times must I generate a random permutation in order to be reasonably assured that I have covered all possible permutations? I'm not sure how to de... | g45279 | [
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-0.001193616772070527,... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/13676/why-does-t-statistic-increase-with-the-sample-size">Why does t statistic increase with the sample size?</a> </p>
</blockquote>
<p>In t test,the test statistic is
$$
t = \frac{\overline{x} - \mu_0... | g49717 | [
0.029010122641921043,
0.06757717579603195,
0.0010864257346838713,
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0.012433355674147606,
-0.033775631338357925,
-0.004286033567041159,
0.013678044080734253,
-0.040569014847278595,
-0.023716064170002937,
-0.013329599052667618,
0.025862528011202812,
0.024754462763667107,
... |
<p>In Gaussian clustering (i.e. General Mixture Models) we model the data with some clusters. For example, in the below figure, we have two clusters $C_1, C_2$, each of which are modeled with a Gaussian (Normal) distribution: $p_{C_1} \sim \mathcal{N}(\mu_1, \Sigma_1)$ and $p_{C_2} \sim \mathcal{N}(\mu_2, \Sigma_2)$ wi... | g23064 | [
-0.03551843762397766,
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0.014561704359948635,
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-0.02857433445751667,
0.06737582385540009,
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-0.010783842764794827,
0.006256023421883583,
0.007804031018167734,
0.058165501803159714,
-0... |
<p>I want to draw a plot in Matlab or Stata. I have a mean and CI for some distribution. there should be a line with the upper end of the line representing the upper CI and the lower end the lower CI and the middle, the average.</p>
<p>I am not sure how to do it or how to search for it. Can anyone kindly help me out ?... | g65066 | [
0.017411254346370697,
-0.028134219348430634,
-0.0007754877442494035,
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0.007699529640376568,
-0.039485860615968704,
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-0.030121222138404846,
0.005205704364925623,
0.005153217352926731,
0.03951876610517502,
... |
<p>If $g=f(x,y)$ is a function of independent random variables $x$ and $y$ then how do we arrive at the expression for the probability density function of $g$, </p>
<p>$$f_G(g) = \iint f_X(x)f_Y(y)\delta(g-f(x,y))\mbox{d}x\mbox{d}y\ ?$$</p>
<p>I have been looking at some statistics books but cannot find it. Neither a... | g23494 | [
0.017275745049118996,
0.037050776183605194,
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0.061566807329654694,
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<p>I have a model for predicting a trajectory (x as a function of time) with several parameters. At the moment, I calculate the root mean square error (RMSE) between the predicted trajectory and the experimentally recorded trajectory. Currently, I minimise this difference (the RMSE) using simplex (fminsearch in matlab)... | g65067 | [
0.02278185822069645,
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0.05129791796207428,
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0.02464... |
<p>By (weak/strong) law of large numbers, given some iid sample points $\{x_i \in \mathbb{R}^n, i=1,\ldots,N\}$ of a distribution, their sample mean $f^*(\{x_i, i=1,\ldots,N\}):=\frac{1}{N} \sum_{i=1}^N x_i $ converges to the distribution mean both in probability and a.s., as sample size $N$ goes to infinity.</p>
<p>... | g23495 | [
0.00038454183959402144,
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0.00789705105125904,
0.017872978001832962,... |
<p>In a research article about sensitivity analysis of an ordinary differential equation model of a dynamic system, the author provided the distribution of a model parameter as Normal distribution (mean=1e-4, std=3e-5) truncated to the range [0.5e-4 1.5e-4]. He then uses samples from this truncated distribution for si... | g43361 | [
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0.019479850307106972,
0.00836650375276804,
0.01473063975572586,
0.02489933744072914,
-0.02... |
<p>I need to process three data frames containing the same subgroups (name). So far I've been using this approach:</p>
<pre><code>results = data.frame(name = factor("dummy"), col1 = 1, col = 2)
for( name in df1$name ) {
new.results = process(name, df1[df1$name == name, ], df2[df2$name == name,], df3[df3$name == nam... | g23498 | [
0.036666423082351685,
0.0015386714367195964,
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-0.05237801373004913,
0.036082200706005096,
0.025284700095653534,
0.005265978164970875,
-0.0... |
<p>In linear regression, is the $R^2$ value enough to assess whether the relationship between the independent and dependent variable is linear? It gives the amount of variability in the dependent variable explained by the independent variable. I know that you can plot residuals versus the x value or residuals versus th... | g65068 | [
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0.025442099198698997,
-0.00... |
<p>I had a question on the interaction depth parameter in gbm in R. This may be a noob question, for which I apologize, but how does the parameter, which I believe denotes the number of terminal nodes in a tree, basically indicate X-way interaction among the predictors? Just trying to understand how that works. Additio... | g65069 | [
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0.05023502930998802,
0.04044464975595474,
-... |
<p>What is the <a href="http://en.wikipedia.org/wiki/Maximum_entropy_probability_distribution" rel="nofollow">maximum entropy distribution</a> for a positive continuous variable, given its first and second moments?</p>
<p>For example, a Gaussian distribution is the maximum entropy distribution for an unbounded variabl... | g65070 | [
0.010170908644795418,
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0.06116176024079323,
-0... |
<p>How to determine the number of critical points for some time series (for example, using gradient)?</p>
<p>As far as I understand I have to do the following steps:</p>
<ol>
<li>Fit the time series with some <em>"curve"</em> function (polynomial, sum of sin, etc.) <em>f(x)</em>.</li>
<li>Use this <em>f(x)</em> as da... | g65071 | [
0.03864167258143425,
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0.017479991540312767,
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0.01017480157315731,
0.0915243923664093,
0.00696... |
<p>I have to plot a graph with log distribution on y axis. The values are: 10^-3..10^3.</p>
<p>What software do you suggest me to use.</p>
<p>My OS is Ubuntu, so I prefer software for Linux.</p>
<p>Thanks.</p> | g65072 | [
0.05330665409564972,
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0.001647271099500358,
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0.06109413504600525,
-0.01... |
<p>I have almost the same questions like this:
<a href="http://stats.stackexchange.com/questions/5347/how-can-i-efficiently-model-the-sum-of-bernoulli-random-variables">How can I efficiently model the sum of Bernoulli random variables?</a></p>
<p>But the setting is quite different:</p>
<ol>
<li><p>$S=\sum_{i=1,N}{X_i... | g65073 | [
-0.04664287716150284,
0.001294208224862814,
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0.011131618171930313,
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0.019547265022993088,
-0.0522351935505867,
0.032461002469062805,
0.04689319059252739,
0.... |
<p>I am trying to do a weighted community analysis. I have association matrices calculated (in <a href="http://myweb.dal.ca/hwhitehe/social.htm" rel="nofollow">SOCPROG</a>) year by year over a 30-year period for a population of 80-100 individuals. I would like to explore how community structure changes over time using ... | g23508 | [
0.055949579924345016,
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0.013961476273834705,
0.034342993050813675,
-0.01864457130432129,
0.04895174130797386,
0.0089... |
<p>I wanted to estimate the difference of two means (say: $\mu_1$ and $\mu_2$). I have the estimate of means (say: $m_1$ and $m_2$) with variance estimates (say: $v_1$ and $v_2$). </p>
<p>How do I calculate the weighted-estimate for difference of means ($\mu_2$ - $\mu_1$)?</p>
<p>I am thinking these two should work ... | g65074 | [
-0.002629026770591736,
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0.04386046901345253,
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0.06344857811927795,
-0.006599231157451868,
... |
<p>Can someone please provide me with a summary of how to optimise multi-layer feedforward neural network architecture using the genetic algorithm? I've read a few papers that say this is an effective method to select architecture, but i'm struggling to do it myself. By architecture I mean the number of layers, and the... | g65075 | [
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0.019556064158678055,
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0.047... |
<p>I try to model the duration until a unit is inspected by a large number of possible explanatory variables.
The duration is non-negative and the explanatory variables are factors and numerical variables.</p>
<p>If I knew the best explanatory variables then I would use <code>glm</code> in R. I find family "Gamma" wit... | g65076 | [
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0.02559334598481655,
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0.010742885060608387,
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<p>Is it ok to try and estimate the parameters $c$ and $p$ of a standard AR(1) model of the form</p>
<p>$$
X_t = c+ pX_{t-1} +e_t
$$</p>
<p>solving the normal equation</p>
<p>$$
\Theta = (X^T X)^{-1}X^TY
$$</p>
<p>where $\Theta$ is the parameter vector, $X$ a vector containing the $X_{t-1}$ values and $Y$ the $X_t$... | g23512 | [
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0.08442056179046631,
0.02890746109187603,
0.023129917681217194,
0.02916792407631874,
0.0... |
<p>In linear regression there are two approaches for minimizing the cost function:
The first one is using gradient descent. The second one is setting the derivative of the cost function to zero and solving the resulting equation. When the equation is solved, the parameter values which minimizes the cost function is giv... | g23513 | [
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0.... |
<p>I have a dataset <code>data</code> about a group of persons developing events with Poisson distribution. These events are uniform and can be recurrent in some of the subjects. Their observation time is different. I tried to use R to calculate the incidence rate (in 1000 person years) of the event in the whole group ... | g16945 | [
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0.0021449322812259197,
0.048728689551353455,
0.022817734628915787,
-0.... |
<p>using this code</p>
<pre><code>pvalue = rep(NA, 100000)
n = c(352, 198, 170)
group = rep(1:3, n)
for (i in 1:100000){
x=c(rnbinom(352, size=0.9563, mu=2.27), rnbinom(198, size=1.0468, mu=2.27), rnbinom(170, size=1.3264, mu=2.27))
kruskal = kruskal.test(x ~ group)
pvalue[i] = kruskal$p.value}
result = length(pvalu... | g23515 | [
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0.011498730629682541,
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0.003045237623155117,
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-0.005359286442399025,
0.028181053698062897,
0.017712511122226715,
-0.01817796751856804,
0.... |
<p>I want to plot high dimensional data on x y plane. For that I know three methods: Principal component analysis (PCA), multidimensional scaling (MDS) and a method from spectral graph theory (using the second and third eigenvectors of the laplacian of the graph or w/e).</p>
<p>What are the different aspects of each t... | g65077 | [
0.04548059403896332,
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0.05053875595331192,
-0.008641970343887806,
0.0581105574965477,
... |
<p>With a flat prior, the ML (frequentist -- maximum likelihood) and the MAP (Bayesian -- maximum a posteriori) estimators coincide.</p>
<p>More generally, however, I'm talking about point estimators derived as the optimisers of some loss function. I.e.</p>
<p>$$ \hat x(\,. ) = \text{argmin} \; \mathbb{E} \left( L(X-... | g43374 | [
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0.029209760949015617,
0.043959841132164,
0.... |
<p>Currently working in Octave, but due to the poor documentation progress is very slow.</p>
<p>What language is easy to learn and use, and well documented to solve machine learning problems? I am looking to prototype on a small dataset (thousands of examples), so speed is not important.</p>
<p>EDIT: I am developing ... | g65078 | [
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0.02947775274515152,
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-0.00... |
<p>I want to fit a regression model to see whether these is changes in the proportion of First-year students over years. I have count data for the total count of First-year students (FirstTimeStudents) and total count of all students (TotalStudents). I want to fit a GEE model with this data and wrote the following c... | g43383 | [
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0.0070225028321146965,
0.0022749663330614567,
0.08589770644903183,
... |
<p>I have a dataset with about 35,000 individuals described by around 15 categorical variables. </p>
<p>I'm trying to study the independence / correlation between these 15 categorical variables. My first idea was to, for each pair of variables, create a contingency table and calculate the $\chi^2$. Then, study the ove... | g65079 | [
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0.006955666467547417,
0.033662524074316025,
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0.017801471054553986,
... |
<p>I am pretty new to statistics and have some data that I think may follow a power-law distribution. However, it includes zeroes. I understand that mathematically zeroes can't work, but conceptually, would the point of a power law be violated if there are some zeroes in the data? If I were to scale the data by adding ... | g35122 | [
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0.035441022366285324,
... |
<p>Does anyone know references for non-asymptotic risk bounds for Gaussian regression. Specifically, I am interested in Bayesian regression with a Gaussian prior on the estimator space, and a Gaussian likelihood. I would like to know any results that bound the difference between the risk of the Bayesian estimator and t... | g23518 | [
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0.030049368739128113,
0.03974751755595207,
0.035125404596328735,
0... |
<p>I'm interested in fitting a linear mixed model with this special variance structure on the random effects $\mathbf{u}$:</p>
<p>$\begin{eqnarray*}
\mathbb{V}\left(\mathbf{u}\right) & = & \mathbf{A}\mathbf{G}\mathbf{A}^{\prime}
\end{eqnarray*}$</p>
<p>This variance structure is very similar to Cholesky and... | g26554 | [
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0.03738757595419884,
-0.023190975189208984,
0.060077957808971405,
-0.0044774548150599,
-0.022566689178347588,
-0.0... |
<p>We designed a RCB experiment and assigned the factor levels to the experimental units randomly inside each block. Let's pretend we changed our mind and we would like to go for a Completely Randomized design. A new completely randomized assignment of factor levels to experimental units is not possible since the exper... | g65080 | [
-0.011848744004964828,
-0.02294754609465599,
-0.003975044470280409,
-0.001916584325954318,
0.0120919831097126,
-0.026449667289853096,
0.06633308529853821,
0.038569316267967224,
-0.03640613704919815,
0.021662967279553413,
-0.021003123372793198,
0.049144428223371506,
-0.04802272096276283,
0.... |
<p>I know just enough about <code>lme()</code> and <code>lmer()</code> to get myself by with simple models, and to get myself into trouble with more complex ones. I'm really confused about the proper way to model some data I'm currently working with, and would be grateful for some help.</p>
<p><strong>The question</s... | g47060 | [
-0.021914493292570114,
-0.054518572986125946,
-0.03082587569952011,
0.03358415141701698,
-0.022573035210371017,
-0.027383947744965553,
0.024352794513106346,
0.016056232154369354,
-0.058794450014829636,
-0.02909250557422638,
-0.008726920001208782,
-0.00035774355637840927,
0.03265662118792534,... |
<p>I'm studying panel data models in my introductory econometrics class, especially random effects models.</p>
<p>Consider the model:
$$y_{it}=x_{it}'\beta +c_i+u_{it}$$
with the assumptions $E[c_i]=0=E[u_{it}]$, $E[c_i^2]=\sigma^2_c$, $E[u_{it}]=\sigma_u^2$, $\text{Corr}(x_{it},c_i)=0$ and $\text{Corr}(x_{is},u_{it})... | g65081 | [
0.0013226562878116965,
-0.02786940522491932,
-0.009247667156159878,
-0.045111335813999176,
0.055760398507118225,
0.02094087190926075,
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0.010641547851264477,
-0.011180723085999489,
0.03946150094270706,
-0.004971171263605356,
... |
<p>Just asking if someone knows why the prediction intervals are quite different when one uses a time series analytic method of estimation <em>versus</em> when one simulates such time series. </p>
<p>For example, I used the forecast package's <code>auto.arima</code> function to get the best fit to my data, say it was ... | g65082 | [
0.029330013319849968,
-0.033038366585969925,
-0.002280913759022951,
0.01290161069482565,
-0.027411935850977898,
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0.05002520605921745,
-0.009831726551055908,
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0.028332091867923737,
0.04828394204378128,
0.0020144276786595583,
0.055129654705524445,
0.... |
<p>I am building a real time machine learning module, which is not based on a huge** sample size, with hyper parameter grid search and cross validation process. I am looking for any insight/advice, as I`m considering one of these options:</p>
<ol>
<li><p>Use cross validation grid search to look for the best hyper-para... | g23525 | [
0.04389346018433571,
0.02736903354525566,
0.016300147399306297,
-0.010987672954797745,
0.01338248886168003,
-0.01945292390882969,
-0.027063759043812752,
0.01338257361203432,
-0.04916912689805031,
0.009492050856351852,
0.021147608757019043,
0.03788086026906967,
-0.011522257700562477,
0.0424... |
<p>I am working my way through <a href="http://greenteapress.com/thinkstats/" rel="nofollow">Think Stats</a>, where the author states that</p>
<blockquote>
<p>"there is no closed form expression for the normal cumulative density
function"</p>
</blockquote>
<p>but does not provide any further details as to why thi... | g65083 | [
0.04534588009119034,
-0.028851628303527832,
-0.001236487296409905,
-0.022799942642450333,
0.016026772558689117,
0.03468286618590355,
0.07930044084787369,
-0.00029052470927126706,
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-0.08656000345945358,
0.016288379207253456,
-0.007181035820394754,
0.0860040932893753,
0.... |
<p>In the literature on hierarchical/multilevel models I have often read about "nested models" and "non-nested models", but what does this mean? Could anyone maybe give me some examples or tell me about the mathematical implications of this phrasing?</p> | g65084 | [
0.017626406624913216,
0.03488558530807495,
-0.006021526176482439,
0.028198959305882454,
0.057566653937101364,
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0.011191193014383316,
-0.014359932392835617,
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-0.026856327429413795,
-0.09024916589260101,
-0.0008351582218892872,
0.05323914811015129,
... |
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