question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have just run a NBGLM and want to know something. If I am aiming to drop the least significant explanatory variables until all explanatory variables are significantly correlated wih the response variable (i.e. model selection finding the strongest variables). What do I do when there is a factor within the model th... | g63364 | [
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<p>I am performing a regression where my dependent variable is the value of a group's <a href="http://en.wikipedia.org/wiki/Diversity_index#Simpson_index" rel="nofollow">Simpson Diversity Index</a>. This index value is constrained by $1/k$ and $1$ (where $k$ is the number of classes), though none of my values approach... | g21020 | [
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<p>As part of my research project, I'm studying the plumage of a species of bird called Brent Goose. The species can be divided into two subspecies, a dark-bellied form and a light-bellied form. The two subspecies are present side by side at a location in Northern England, whereas in Southern England, only dark-bellied... | g21021 | [
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<p>I have categorical data in the form of Y/N of 23 attributes and containing 200+ records. I need to compute the distance between the attributes with their class label. Which metric can be used?</p> | g21022 | [
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<p>I have posted this question before but wanted to give a more thorough explanation of my problem so as to hopefully garner some assistance. I am also posting it on Talk Stats under the same title.</p>
<p>I have a mutiple regression model with over 10,000 records and though the model has an R^2 of 91%, the lack of fi... | g21024 | [
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<p>I'm sure many people will respond with links to 'let me google that for you', so I want to say that I've tried to figure this out so please forgive my lack of understanding here, but I cannot figure out how the practical implementation of a neural network actually works. </p>
<p>I understand the input layer and how... | g21025 | [
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<p>I am designing a data capture method for a client for inplay sporting events and he wants to record the odds movements for later analysis in Excel once every half second. I want to get this right so that it's easy to use the data down the line for analysis in other packages.</p>
<p>A bit more background and assumpt... | g63365 | [
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<p>I'm working up a taxonomy showing different methods used in pattern recognition and I'd be curious to hear about how it could be improved. The Mind Map groups different methods based on the discipline which influenced their development.</p>
<p><img src="http://bentham.k2.t.u-tokyo.ac.jp/media/zoo.png" alt="taxonomy... | g63366 | [
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<p>I calculated the confidence intervals for the regression coefficients using the formula: SE X 1.96. I then took this value away from the regression coefficient to get the lower confidence level and added it to the regression coefficient to get the upper confidence level. However, for those z tests and associated p v... | g63367 | [
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<p>I need to run Newey West t statistics in SAS 9.2. I already run regression, White's test, Breusch Godfrey test and Jarque-Bera normality test.
Regression is simple. Number of observations = 522
Depended variable name: rtest 1
Independent variable name: rtest 2
Data are time series data.</p>
<p>I found somewhere th... | g21026 | [
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<p>I have downloaded the Gaussian Processes for Machine Learning (GPML) package (gpml-matlab-v3.1-2010-09-27.zip) from the website,
and I can run the regression example (<a href="http://www.gaussianprocess.org/gpml/code/matlab/doc/index.html" rel="nofollow">demoRegression</a>) in <a href="http://www.gnu.org/software/oc... | g63368 | [
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<p>If I have 5 binary variables with values for 100 observations to give me a 5x100 matrix.</p>
<pre><code> y1 y2 .... y100
x1 0 1 .... 1
x2 0 0 .... 0
x3 1 0 .... 0
x4 1 1 .... 1
x5 0 0 .... 0
</code></pre>
<p>I want to put the observations into fairly homogeneous groups based on their values from ... | g27154 | [
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<p>Suppose there is an experiment that in each trial returns a two vector of probabilities of size $n$. In each trial I select uniformly a number from ${1,\cdots, n}$ and compare that element in this two vectors. I want to see if in a large number of trials, that randomly selected element of first vector is greater tha... | g21028 | [
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<p>If there are two samples from a distribution whose form is not known, and which is certainly not normal, how can one ascertain the probability that, by random chance, their means/medians are dissimilar? In other words, is there a t-test equivalent for samples coming from a distribution of unknown form?</p> | g63369 | [
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<p>I'm computing cosine similarities between 2 vectors.</p>
<p>These vectors are information retrieval query and document representations respectively.</p>
<p>They have been computed using <a href="http://en.wikipedia.org/wiki/Tf%E2%80%93idf" rel="nofollow">tf-idf</a> weights.</p>
<p>Since my documents have differen... | g21030 | [
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<p>Assume a classification problem where there are two classes and the aim is to detect a consistent pattern which successfully separates the input dataset regardless of how we divide it into training / testing. The broader question is does such a consistent pattern exist across different partitions of the dataset at h... | g63370 | [
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<p>My goal is to create a formula that can give an indication of how a YouTube channel's video will perform in the first 30 days of its lifespan and eliminate viral video / "lightening in a bottle" outliers that may be on the channel. The goal is to use the resulting number to price a video from a specific YouTube chan... | g63371 | [
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<p>I am trying to estimate the school effects on student scores. I ran a model with student effects as a random effect and school effects as fixed effects as follows:</p>
<p>xtreg studentscore lagstudentscore limitedEng poor <code>gradeyeardum'</code>schoolyeardum', re</p>
<p>where student score is regressed on lag o... | g63372 | [
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<p>im analyzing an article for my studies with the hypothesis if a change in work motivation ist related with a change in mental well being (<a href="http://www.sciencedirect.com/science...01879113001541" rel="nofollow">http://www.sciencedirect.com/science...01879113001541</a>). Sadly i dont know much about poisson reg... | g63373 | [
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<p><strong>Intro:</strong> Having noted the attention received today by this question, "<a href="http://stats.stackexchange.com/q/83030/32036">Can ANOVA be significant when none of the pairwise t-tests is?</a>," I thought I might be able to reframe it in an interesting way that would deserve its own set of answers.</p>... | g63374 | [
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<ol>
<li><p>Are there any particular assumptions regarding the errors for logistic regression such as the constant variance of the error terms and the normality of the residuals?</p></li>
<li><p>Also typically when you have points that have a Cook's distance larger than 4/n, do you remove them? If you do remove them, h... | g63375 | [
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<p>I'm comparing plausible models selected a-priori to predict a binary response variable. I used binary logistic regression in SPSS20 and obtained AIC=-2*LogLikelihood+2k where k is the number of parameters in the model. Using the GLM procedure (binary logistic) I get provided with AIC, AICc, BIC etc. straight away, h... | g639 | [
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<p>Suppose I have $\sigma|Y,Y*,\psi$~$Inverse-Gamma(A, B)$. </p>
<p>How should I get $\sigma^2$. Can I just square the result from Inverse-Gamma? </p>
<p>To me, this seem to work, if you think of it this way: $\sigma$ is the standard deivation and $\sigma^2$ is the variance, and this relationship is one-to-one. Y... | g21036 | [
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<p>I'm currently studying for my finals in basic statistics for my ECE bachelor.</p>
<p>While I think I have the math mostly down, I lack intuitive understanding what the numbers actually mean.(Preamble: I'll use rather sloppy language).</p>
<p>I know the E[X] is the "weighted average" of all results of X weighted by... | g63376 | [
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<p>I have a cluster of p-dimensional points and given a new p-dimensional point $x$ I want to determine whether or not it is likely to belong to this cluster. </p>
<p>The cluster is made up of $n$ p-dimensional points, I am making the assumption that these points are drawn from a multivariate Gaussian distribution wit... | g21039 | [
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<p>I'm trying to figure out whether leverage plots can provide valuable information. See example <a href="http://www.jmp.com/support/help/Leverage_Plot_Details.shtml" rel="nofollow">here</a>.</p> | g63377 | [
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<p>Why is the area under the curve measure better than the accuracy ratio?</p>
<p>I know that the AR lies between 0,5 and 1 and the relationship
$AUC=\frac{1}{2}(AR+1)$ holds, so the AUC lies between 0,75 and 1, but this does not really seem to be an advantage.</p> | g21040 | [
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<p>I am computing multiple regression coefficients for these variables (for several cases):</p>
<pre><code> y,x1,x2,x3
log(y)= a(log(x1))+b(log(x2))+c(x3)+d
res=lm.fit(log(y)~log(x1)+log(x2)+(x3))
</code></pre>
<p>All values of <code>y,x1,x2,x3</code> are between <code>0 and 1</code>.</p>
<p>The va... | g63378 | [
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<p>I have a set of 1200 time series for which I need to build a forecasting model. Since it is too time consuming to build a model for each series, I separated the series into clusters and what I want to do now is to build a forecasting model for each cluster (using time series techniques).</p>
<p>However, I don't kno... | g63379 | [
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<p>I need to estimate baseline hazard function $\lambda_0(t)$ in a time dependent Cox model</p>
<p>$\lambda(t) = \lambda_0(t) \exp(Z(t)'\beta)$</p>
<p>While I took Survival course, I remember that the direct derivative of cumulative hazard function ($\lambda_0(t) dt = d\Lambda_0(t)$) would not be a good estimator bec... | g63380 | [
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<p>I have a large table of attributes of different real-world movie theaters. I have classified them by the "true" physical entity to which they belong, so that there may be multiple records for a given movie theater entity.</p>
<p>In this table, I have information such as names, how many screens they have, etc. Given... | g21043 | [
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-0.043594032526016235,
-0.005170242395251989,
0.019827887415885925,
0.010314660146832466,
0.09721601009368896,
-0.... |
<p>Andrew Gelman in one of his recent blog posts says:</p>
<blockquote>
<ol>
<li><p>I do not think counterfactuals or potential outcomes are necessary for Simpson’s paradox. I say this because one can set up Simpson’s
paradox with variables that cannot be manipulated, or for which
manipulations are not directl... | g63381 | [
0.0027978282887488604,
0.029604213312268257,
0.008095492608845234,
-0.0006959347520023584,
0.03993038833141327,
0.011305711232125759,
0.09059884399175644,
-0.04460114613175392,
0.011455194093286991,
-0.005527224857360125,
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0.03492017090320587,
0.06664872914552689,
-0.... |
<p>I have been analysing a number of likert scale variables using spatial auto-regressive models. However, my question I think can be applied to an OLS model. </p>
<p>After analyzing the data I obtained some odd coefficients, which led me to realize that some of the variables were coded inversely. That is, 1 was very ... | g63382 | [
-0.02705445885658264,
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0.06129785627126694,
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0.019413815811276436,
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0.00716083450242877,
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0.08810631185770035,
0.07072688639163971,
-0.... |
<p>I'm doing some basic one-way ANOVA in R. It would be useful to be able to output only the p-value associated with a <em>specific</em> term without producing the whole ANOVA table (unrelated reason). I need the value as a basic numeric and not an ANOVA object For example, if I'm looking at <code>anova(lm(yield~variet... | g63383 | [
-0.0013760986039415002,
0.013537613674998283,
0.0063674356788396835,
-0.016669336706399918,
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-0.012490608729422092,
-0.002332729520276189,
0.046057794243097305,
0.0840581655502319... |
<p>Is it possible to do stochastic population forecasting with the R package Demography when the population size is between 10k and 20k? I have data from year 1985 to 2012 for population, deaths and births. What do you do when almost half of the death rates are 0? From ages 1 to 30 nearly no one dies in a so small popu... | g63384 | [
0.01940523460507393,
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0.009509125724434853,
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0.02769249677658081,
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0.002388759981840849,
0.0030732816085219383,
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0.050984498113393784,
-0... |
<p>For a manuscript intended for submission to a medical (or psychological) journal, I have cognitive data from 16 patients and 32 age- and gender-matched healthy controls at four time points (pre-treatment T0, and three post-treatment time points T1, T2, and T3 in patients; in controls at the same intervals), i.e., I ... | g63385 | [
-0.031633734703063965,
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-0.0511026494204998,
-0.019103411585092545,
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0.04330796003341675,
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0.03007921203970909,
-0.009721231646835804,
0.007028508000075817,
-0.019122188910841942,
... |
<p>I have a set of real numbers. I need to estimate the quantile of a new number. Is there any clean way to do this in R? in general?</p>
<p>I hope this is not ultra-trivial ;-)</p>
<p>Much appreciated for your response.</p>
<p>PK</p> | g28641 | [
-0.020434794947504997,
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0.014592304825782776,
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0.04073692858219147,
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0.03066113218665123,
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... |
<p>So I have two related questions. I am performing a logistic regression model and want to know how to enter these variables.</p>
<p>1) For one survey I have questions and the responses are Yes, Don't know, and No. Can I just create a dummy variable for Yes (1) with Don't know and No coded as 0 or do I need to excl... | g63386 | [
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0.027839338406920433,
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0.039332762360572815,
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0.032577335834503174,
0.011395002715289593,
... |
<p>I would like to setup up an algorithm for detecting an anomaly in time series, and I plan to use clustering for that. </p>
<ul>
<li><p>Why should I use a distance matrix for clustering and not the raw time series data?, </p></li>
<li><p>For the detection of the anomaly, I will use density-based clustering, an algor... | g40340 | [
0.049208495765924454,
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0.01343128178268671,
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0.08168081194162369,
... |
<p>How can we compare complexity of two models with the same number of parameters?</p>
<p><b>Edit 09/19</b>: To clarify, model complexity is a measure of how hard it is to learn from limited data. When two models fit existing data equally well, a model with lower complexity will give lower error on future data. When a... | g63387 | [
-0.005603340920060873,
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0.013807440176606178,
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0.011110441759228706,
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0.035838086158037186,
0... |
<p>I need to query an internet time server, in order to assess the staleness of streamed data I am receiving on another channel. I periodically make 3 successive queries, then use the combined error to adjust my system clock until the next set of 3 queries.</p>
<p>Each query returns an accurate time from the remote s... | g63388 | [
0.006619065534323454,
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0.021026674658060074,
0.06960185617208481,
0.03500102460384369,
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... |
<p>I am working on my thesis and working machine learning. The overall problem is Detecting and Recognition of Road Inventory.</p>
<p>For my research part I am looking into decision trees, especially Hough forests. There are some areas where I need more information and if anyone else have worked with this I might save... | g63389 | [
-0.02492447942495346,
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0.00951339676976204,
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0.0327581949532032,
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0.0779515728354454,
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0.039630282670259476,
-0.04327518492937088,
0.05957736074924469,
-0.011374... |
<p>Suppose I have a number of samples drawn from a normal distribution $x_i \sim \mathcal{N}(\mu,C)$ with $i = 1 \dots n$. I can make observations $z_i = x_i + e_i$ for those samples which are perturbed by noise $e_i$ of known characteristic $e_i \sim \mathcal{N}(0,\Sigma_i)$. Note that the distribution of the observat... | g63390 | [
0.029720472171902657,
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0.031202202662825584,
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0.05655617266893387,
0.01020263135433197,
-0.003991211298853159,
0.05547674745321274,
-0.017102109268307686,
0.04424459859728813,
0.01596536859869957,
0.045... |
<p>A few months ago I posted a question about homoscedascity tests in R on SO, and Ian Fellows answered that (I'll paraphrase his answer very loosely) "homoscedascity tests are not a good tool when testing the goodness of fit of your model. With small samples, you don't have enough power to detect departures from homos... | g21051 | [
0.027163498103618622,
-0.0388847254216671,
0.011796807870268822,
0.023585235700011253,
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0.04369211941957474,
0.014473534189164639,
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0.005119512788951397,
0.052754465490579605,
0.01596805639564991,
0.012314623221755028,
0.073... |
<p>Assume you have a model of the form $y = x_1\Phi(\beta_0 + \beta_2x_2 +\ldots+ \beta_nx_n)+u$ where $y_i\in(0,x_{1i}]$ and $\Phi$ is the probit function.</p>
<p>How can we estimate $\beta$s in e.g. Stata?</p> | g63391 | [
-0.01761765591800213,
0.008785094134509563,
0.006767566781491041,
0.00012616542517207563,
0.09159526973962784,
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0.0030054058879613876,
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-0.02108025550842285,
-0.07445498555898666,
0.056973062455654144,
-0.003241990227252245,
... |
<p>I'm trying to do some really simple Time Series work. I started off looking at monthly counts but the more I thought about it (and the more I read posts by IrishStat) the more I realised my view of this was fundamentally flawed. My main reason for thinking this is the plethora of timing issues there are with using m... | g63392 | [
0.01891377940773964,
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0.0029856497421860695,
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0.038274575024843216,
0.020707206800580025,
0.03116029128432274,
-0.05303556099534035,
0.022280927747488022,
-0.03981424495577812,
0.05923675000667572,
0.05... |
<p>As a computer scientist, you often face the problem to empirically analyse the improvements in run time of some algorithm. </p>
<p>I stumbled over the following text in a paper:</p>
<blockquote>
<p>These run times are averages over 10 runs per benchmark, and account
for time-outs using maximum likelihood estim... | g63393 | [
0.03929400071501732,
0.04250197857618332,
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0.004161426331847906,
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0.02778482437133789,
0.022953784093260765,
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0.056849490851163864,
0.007817825302481651,
-0.0032113343477249146,
0.03729208931326866,
0.07... |
<p>I've just been given a stack of polling data to analyse. Some of the questions are obviously leading or present subtle incentives (for the poller or polled) for specific answers. Of other questions I'm not so sure but I have some doubts. I'm also starting to question other factors about how the poll was conducted (e... | g63394 | [
0.02216392755508423,
0.04907732829451561,
0.005711932200938463,
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0.04144270718097687,
0.018260454759001732,
0.023561617359519005,
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0.040016233921051025,
0.00803951732814312,
0.05366699397563934,
-0.0008867934811860323,
0.023096542805433273,
0.04... |
<p>This question seems easy but I am not getting it. Let $X_{1},X_{2}, · · · ,X_{15}$ be a random sample from a normal population
$X ∼ N(0, σ^2)$. Find a best critical region of size $α = 0.05$ for testing $H_{0} : σ_2 = 1$
versus $H_{2} : σ_{2} = 4$.</p> | g63395 | [
0.03463190421462059,
0.00781805720180273,
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0.006855257786810398,
0.040645353496074677,
0.03032343089580536,
0.004790842067450285,
-0.... |
<p>I have developed a method to estimate a certain value called "flow" from 10% of the total data received (the total data may change every time) but of course there is an error associated with my method. My data comes from simulation that I can run as many times that I want. with how many 10% samples do I have to test... | g21054 | [
0.032805029302835464,
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0.004109353758394718,
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0.029991695657372475,
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-0.04375693202018738,
0.014120918698608875,
0.0013408504892140627,... |
<p>If I have 3 groups that I want to compare with a t-test (correcting for multiple comparisons afterwards) but one of the groups has different variance than the other two, should I use a Welch correction for all comparisons or just for the comparison involving the group with unequal variance?</p> | g24898 | [
0.0350910909473896,
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0.011104017496109009,
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0.006873877719044685,
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0.031507108360528946,
0.02524287812411785,
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-0.023871218785643578,
0.0... |
<p>I´m beginner with SPSS and I have on problem on interpreting binary logistic results. So I have this table: </p>
<p>Variables in the Equation </p>
<pre><code> B S.E. Wald df Sig. Exp(B)
Step 1ais_first_timer -1.582 .129 149.593 1 .000 .20... | g40347 | [
-0.03264657407999039,
0.027639854699373245,
-0.01774049922823906,
-0.04510922357439995,
-0.004968748893588781,
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0.040586285293102264,
0.03977466747164726,
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-0.03577139228582382,
-0.02926155924797058,
0.06046279892325401,
0.055225759744644165,
0.03... |
<p>I have the following data frame</p>
<pre><code>structure(list(Chi = structure(c(1L, 1L, 5L, 5L, 6L, 9L, 9L,
12L, 13L, 14L, 14L, 16L, 16L, 19L, 19L, 20L, 20L, 23L, 24L, 24L,
26L, 26L, 31L, 31L, 33L, 33L, 36L, 37L, 37L, 40L, 40L, 43L, 43L,
44L, 44L, 45L, 46L, 47L, 47L, 48L, 48L, 52L, 52L, 54L, 54L, 55L,
55L, 56L,... | g63396 | [
0.005892341490834951,
-0.05024685338139534,
0.02776457741856575,
-0.08908717334270477,
0.04692583531141281,
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0.08754261583089828,
-0.020293593406677246,
-0.012482918798923492,
-0.06723891198635101,
-0.01926913671195507,
0.0415811687707901,
0.04626155272126198,
-0.04314... |
<p>This is a pretty simple question and I'm wondering how to go about finding a solution. I have the following data. </p>
<pre><code>ttt = data.frame(name=c("A","B","C","D","E","F"),
count=c(150,250,350,550,150,50),
returns=c(10,50,60,100,80,10),
calls_bad=c(5,30,20,1... | g40349 | [
0.06291396170854568,
0.0025931361597031355,
-0.03417039290070534,
-0.025434385985136032,
0.04074726998806,
-0.028497327119112015,
0.02310291863977909,
0.015523092821240425,
-0.06436850130558014,
-0.0585603192448616,
0.026071568951010704,
0.009340882301330566,
0.06206601485610008,
0.0348050... |
<p>I am running a Cox regression analysis in R where both my predictors are binary (<code>Animal_Number</code>: <em>single</em> vs. <em>paired</em>; and <code>Treatment</code>: <em>control</em> vs. <em>exposed</em>). I therefore have four groups (<em>single control</em>, <em>paired control</em>, <em>single exposed</em>... | g63397 | [
-0.009676438756287098,
-0.08328317105770111,
-0.02585074119269848,
-0.012277049012482166,
0.0794457197189331,
-0.03238967806100845,
0.05028610676527023,
0.054107360541820526,
-0.01932518370449543,
-0.045646730810403824,
-0.020887713879346848,
0.04369509965181351,
0.043457191437482834,
0.05... |
<p>I have fit several generalized mixed models for a multinomial distribution data in SPSS.</p>
<p>I want to select the best one for explaining my data. But comparing the AIC and selecting the lower AIC model gives me a model without sense and its accuracy is lower than others with higher AIC. </p>
<p>I want to test ... | g63398 | [
0.010544180870056152,
-0.06534700095653534,
0.010509862564504147,
0.0017171084182336926,
0.003076360560953617,
-0.04462350904941559,
0.005529002286493778,
-0.0017855953192338347,
-0.025135288015007973,
-0.005797474645078182,
-0.039016444236040115,
-0.01499098353087902,
0.07483293861150742,
... |
<p>I get a <code>floating point overflow</code> error while using <code>proc corr</code> to compute correlations among transformations (exponential and log) of variables. How to avoid this?</p> | g21058 | [
0.05585795268416405,
0.00441810442134738,
-0.00008637038263259456,
-0.09437968581914902,
0.06695573776960373,
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0.08662918210029602,
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-0.024018919095396996,
0.010569559410214424,
0.029981005936861038,
0.038124147802591324,
0.... |
<p>I'm trying to estimate the statistical properties of a 3D vector field (the magnetic field vector in the solar atmosphere) over a 2D field of view from observations. I will neglect for the moment that the problem is complex because I cannot measure directly the vector field but only some quantities (the Stokes profi... | g40353 | [
0.0009023862658068538,
-0.011550238355994225,
-0.0066973441280424595,
0.0044408803805708885,
0.004773342981934547,
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0.008151729591190815,
-0.038676049560308456,
-0.06340698152780533,
-0.030551889911293983,
0.01319877989590168,
0.014647848904132843,
0.006753577850759029,
... |
<p>I am trying to intelligently bin a sorted collection. I have a collection of $n$ pieces of data. But I know that this data fits into $m$ unequally sized bins. I don't know how to intelligently choose the endpoints to properly fit the data. for example:</p>
<p>Say I have 12 items in my collection, and I know the dat... | g40354 | [
0.004879426211118698,
0.06230323389172554,
0.022775109857320786,
-0.04949329420924187,
0.013067087158560753,
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0.030651312321424484,
-0.027590567246079445,
-0.020096104592084885,
-0.02582971192896366,
-0... |
<p>It is well known, that there are diffrent types of scales (see Wikipedia <a href="http://en.wikipedia.org/wiki/Level_of_measurement" rel="nofollow">Level of measurement</a>).</p>
<p>In psycholinguistics there is <a href="http://en.wikipedia.org/wiki/Semantic_differential" rel="nofollow">Semantic Differential techni... | g63399 | [
0.028692619875073433,
0.003825470106676221,
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0.05658815801143646,
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0.02537272498011589,
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-0.02378815785050392,
0.00502969603985548,
-0.025082232430577278,
0.042794596403837204,
0.00... |
<p>I've had it put to me by a couple of statistics teachers that statements of this kind are just loose talk. This seems to relate to the discussion of the Neyman-Pearson framework I've read about at <a href="http://stats.stackexchange.com/questions/23142/when-to-use-fisher-and-neyman-pearson-framework">When to use Fis... | g63400 | [
-0.0030740590300410986,
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0.008412711322307587,
-0.0861811563372612,
0.024196727201342583,
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0.039149072021245956,
0.006299450993537903,
0.0010209284955635667,
-0.00850049126893282,
0.02872779406607151,
-0.018929265439510345,
0.036253392696380615,
... |
<p>Suppose $X_1,...,X_n$ follow a $U(t,t+1)$ distribution. Show that the UMP level alpha test for testing $H_0:t<=t^*$ vs $H_1:t>t^*$ has form:</p>
<p>Reject $H_0$ if and only if $\min(X_1,...,X_n)>t^* + c(\alpha)$ or
$\max(X_1,...,X_n)>t^*+1$ for some appropriate $c(\alpha)$.</p> | g63401 | [
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<p>I'm trying to link statistical analysis methods to validable business observations. Ideally an interpretation that is measureable and can objectively rank success of predictions.</p>
<p>For the frequentist p-value of 0.95 I figured the statement is:
There are instances - some of which have a real effect and some ar... | g21064 | [
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<p>At work I have decided to use a classification tree to do some analysis on the people at the bottom decile for hourly pay. Mainly for inferential reasons. </p>
<p>My datasets are broken up in years, I have 2013, 2012, ... , 2006. I just wanted to know if I can build trees for each of those years, and then compare a... | g63402 | [
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<p>I have a small (n = 60) dataset where I would like to estimate the magnitude of the relationship between a set of predictor variables (among others) and an outcome rate variable.</p>
<p>Because the number of trials for the outcome variable differs dramatically between cases, it seems natural to weight each case by ... | g2068 | [
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<p>Does it make sense to compute confidence intervals and to test hypotheses when data from whole population is available? In my opinion, the answer is no, since we can accurately compute true values of paramaters. But then, what is the maximal proportion of data from original population that allows us to use aforement... | g63403 | [
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<p>I am attempting to compare two diagnostic odds ratios (DORs). I would like to know of a statistical test which will allow me to do this. Please help! Thank you!</p> | g21067 | [
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<p>In the toy example given below, is it enough to show that the model fitted weel? Is there any other metric available to show the fitness?
Thanks </p>
<pre><code>library(rpart)
N <- 1000
X1 <- runif(N)
X2 <- 2*runif(N)
X3 <- ordered(sample(letters[1:4],N,replace=TRUE),levels=letters[4:1])
X4 <- facto... | g63404 | [
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0.0... |
<p>My thesis coach wants me to perform a predictive analysis based on OLS. What I understand is the following:</p>
<ul>
<li>divide the dataset into a training set and a holdout set, for instance 50-50</li>
<li>perform OLS on the training set</li>
<li>construct linear equation based on regression output</li>
<li>create... | g21071 | [
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<p>Consider the following OLS output. My question is: If you have to define a linear equation from the regression, do you then only include significant variables? If so, the equation according to the SPSS output (DV = <code>stockVol0LN</code>) would be:</p>
<pre><code>stockVol0LN = 0.632 * StockVol1LN + 0.278 * StockV... | g63405 | [
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<p>I need to reduce the dimensionality of motion capture data $M=\{x,y,z,\theta\}$ where $x,y,z$ are the pixel coordinates and $\theta$ is the Euler angle/joint angle. This data is obtained from skeletal markings in video frames. So, for 10 joints I have 10 such sets of time series data giving a total of 4*10=40 time s... | g63406 | [
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<p>Say I am using regression analysis to try and estimate the assembly time for widgets (which can be produced in various sizes) given some possible independent variables:</p>
<ul>
<li>Width</li>
<li>Height</li>
<li>Quantity of pieces (different sizes used as components)</li>
<li>Did the American League win the World ... | g11519 | [
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<p>I'm doing a Poisson regression in Stata, so the dependent variable is a count variable and I have some categorical predictors. If A is a categorical variable with, for example, 4 levels, in the parameter estimates table I get results for the 3 levels of the variable compared to the level I have set as the reference ... | g63407 | [
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<p>I observe a series of crime incidents linked by <em>modus operandi</em> or some other peculiar characteristic of the crime (e.g. cutting catalytic converters from underneath vehicles). I would like to know if the observed days of the week that the crimes occur on (ignoring the uncertainty that sometimes occur in cri... | g63408 | [
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<p>Dummy (or binary) variables ($X_2$) can be used in linear regression models to help explaining a possible group effect that a continuous predictor variable ($X_1$) might present in explaining the response variable ($Y$).</p>
<p>Now, I am wondering if it makes sense to have only dummy variables as predictors in a li... | g63409 | [
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<p>A non-stationary $AR(1)$ process, which is a random walk, is constant in mean, but not constant in variance. How about the other $AR(p)$ processes with the order $p>1$? Are they constant in mean?</p> | g21078 | [
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<p>I'm estimating several inverse covariance matrices of a set of measurements across different subpopulations using an wishart prior in jags/rjags/R. </p>
<p>Instead of specifying a scale matrix and degrees of freedom on the inverse covariance matrix prior (the wishart distribution), I would like to use a hyperprior ... | g63410 | [
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<p>I'm looking for breakpoints in species abundance as a function of spatial distance, using the <code>segmented</code> package for R. 'segmented' appears to return a breakpoint no matter what; I don't understand whether it returns an estimate of the signifcance of the breakpoint (or whether the segmented linear model ... | g63411 | [
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<blockquote>
<p>After centring, the two measurements x and −x can be assumed
to be independent observations from a Cauchy distribution with
probability density function:</p>
<p>$f(x :\theta) = $ $1\over\pi (1+(x-\theta)^2) $ $, -∞ < x < ∞$</p>
<p>Show that if $x^2≤ 1$ the MLE of $\theta$ is 0, but... | g63412 | [
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<p>I ran an ANOVA with 4 predictors (2 categorical, 2 continuous) and 1 covariate (continuous). Including the covariate did not significantly alter the main effects of the ANOVA when it was run without the covariate. I then found that one of the categorical variables had a significant effect on my covariate (i.e. the c... | g63413 | [
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<p>Forgive me if this question is redundant; predicted values and regression returns many results. </p>
<p>My question is this:</p>
<p>I would like to run one regression and generate predicted values based upon a subset of the variables in that regression. With these predicted values I then want to regress them on ot... | g63414 | [
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0.0... |
<p>Ok, after trying to find a way to get all lagged and non-lagged - correlations from multiple time-series (behavioral series with length around 180) I've confined myself to the following:</p>
<p>I have multiple (5 so far, more coming) sets of 12 time-series with equidistant measurements, same sampling-times $t_1, t_... | g63415 | [
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<p>I'm running a rather simple multilevel model in which I have two variables interacting at level 1. The interaction term is significant, but I'm not sure how to interpret it properly. I am familiar with doing interaction analyses in linear regression, do I do the same steps?</p>
<p>I'm using Stata, in case that's of... | g38600 | [
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<p>What are the most popular references (especially texts) you think in the area of mixed models? Or what are those you think were helpful to you when you learnt this topic?</p> | g63416 | [
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<p><img src="http://i.stack.imgur.com/rrHOF.png" alt="enter image description here"></p>
<p>I'm asked to find association rules with support >= 0.3 and confidence >= 0.6. For support as a percentage, we need to divide the support of the candidate itemset by the the total number of records at each k-item stage of the ... | g21083 | [
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<p>I have fitted a model of current species habitat suitability as a function of mean annual temperature (MAT) and precipitation (MAP) by regressing the distribution of known occurrences of a species with respect to these variables across space using GBM. Now I have a colleague that wants to employ this model to look a... | g21084 | [
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<p>I have 20 human subjects doing a task under 2 different difficulty conditions. (So it's a repeated measures design)</p>
<p>Each person has a different performance in each of the task difficulty conditions, so I can rank-order them.
I want to test whether there are differences between the ranking of performaces bet... | g63417 | [
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<p>I am trying to understand the mechanism underline multiple imputation ideas. I am confusing on creating multiple sets of estimates and then average them. For example:</p>
<pre><code>set.seed(123)
df<-data.frame(
x1=rnorm(100,10,2),
x2=rbinom(100,20,0.6))
y=rbinom(100,1,0.5)
#set missing values
ms<-sample... | g63418 | [
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0.... |
<p>I'm working with biological sequence data where each position in the sequence has an associated continuous value. I'm ignoring the sequence content so the data is very similar to a time series with measurements at discrete timepoints -- all values are equally spaced. I would like to be able to detect whether high ... | g63419 | [
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... |
<p>Here is the task:</p>
<p>I have a sample of replies to my e-mail from my mail box. A sample is taken over a period of 90 days, 1000 e-mails and replies if any. (We only consider a pair of {my original e-mail, date}, {reply, date}). Question: how many days should I wait to conclude I will never get a reply from this... | g63420 | [
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<p>I have seen this statement in a <a href="http://www.stat.cmu.edu/~cshalizi/ADAfaEPoV/ADAfaEPoV.pdf" rel="nofollow">lecture note</a> :</p>
<p>$$E[(Y-f(X))^2\,|\,X]=Var[Y|X]+E^2[(Y-f(X)\,|\,X]]$$</p>
<p>If $Z,X$ are random variables, then shouldn't be
$Var[Z|X]=E[Z^2|X]-E^2[Z|X]$?In which case shouldn't the term $V... | g63421 | [
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<p>I have a bunch of independent <em>p-values</em> and now I want to combine them using the <a href="http://en.wikipedia.org/wiki/Fisher%27s_method" rel="nofollow">Fisher's method</a>. However, in R, when the p-value is zero, the <code>log(p-value)</code> becomes $-\infty$, so that the test statistic $X^2$ is $\infty$.... | g63422 | [
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-0.011863136664032936,
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0.022099407389760017,
0.032233670353889465,
0... |
<p>I am beginner of R software. I am looking for two variables and result cross tabulated but not in the form of frequencies. Could I get help on how to get result as average and standard deviation instead of frequencies while cross tabulating in R.
my data looks like this</p>
<pre><code>Treatment Stage Chlorophyl... | g63423 | [
0.036764804273843765,
-0.055384036153554916,
0.01960207335650921,
-0.05996926873922348,
-0.0015294855693355203,
-0.026483790948987007,
0.05873962864279747,
-0.017695480957627296,
-0.037960074841976166,
0.012900073081254959,
0.028511177748441696,
-0.005794499069452286,
0.01556419488042593,
... |
<p>I'd like to use bootstrapping in my two-way ANOVA containing two fixed and one random factor. Why is the bootstrapping method not available (greyed out) for models containing a random factor?</p>
<p>Thanks!</p> | g139 | [
-0.010856454260647297,
0.010893408209085464,
0.029133303090929985,
0.02027411013841629,
0.03472113981842995,
0.01014985702931881,
-0.001845457823947072,
-0.01679280214011669,
-0.03806570917367935,
-0.046347688883543015,
0.0006877465639263391,
0.009772319346666336,
0.03660448268055916,
0.08... |
<p>I'm having a problem in doing a GARCH(1,1) regression. I'm trying to regress gold prices serie on stock returns series as in the following equation in eviews:
$$
r = c(1) + c(2) \cdot s + c(3)\cdot d10\cdot s +c(4)\cdot d05\cdot s + c(5)\cdot d01\cdot s ,
$$
where $r$ is gold prices, $s$ stands for stock prices and... | g63424 | [
0.033785365521907806,
-0.028725674375891685,
-0.033226657658815384,
-0.003688633907586336,
0.06976532191038132,
-0.007231902796775103,
0.02333005703985691,
-0.0010843140771612525,
0.005388109479099512,
-0.01901954598724842,
-0.03982355818152428,
0.11021324247121811,
0.006599916145205498,
-... |
<p>Let's say that I have a method of sampling from $P(X, \theta \mid Y)$. It seems intuitive that if I drew samples of $(X, \theta)$ and then simply dropped the $\theta$s, this is equivalent to drawing from $P(X \mid Y)$ directly. What is the theorem that says that I can do this?</p> | g63425 | [
0.02109091728925705,
-0.020611191168427467,
-0.007816233672201633,
-0.08586336672306061,
-0.009392325766384602,
-0.01682061143219471,
-0.011264212429523468,
-0.05015481635928154,
-0.030050113797187805,
-0.018188035115599632,
-0.04409632086753845,
-0.0004716447729151696,
0.047094278037548065,... |
<p>Suppose that we take a sample ($X_1, X_2, ... X_n$) from a distribution where we assume that $X_i $~$ Bin(n_i, p_i)$ and $n_i$ is known for every $i$. We also assume that $p_i$'s are independent and identically distributed, $p_i$ ~ $D$, where $D$ is some unknown distribution.
$n_i$ cannot be assumed to be large.</... | g63426 | [
0.036310769617557526,
0.0017378820339217782,
-0.005068466532975435,
-0.05634911358356476,
-0.056936878710985184,
-0.003966883290559053,
-0.04438481852412224,
0.004402037709951401,
-0.011722005903720856,
-0.015178855508565903,
0.014158262871205807,
0.024380717426538467,
0.05144467577338219,
... |
<p>Sorry if this question comes across a little basic.</p>
<p>I am looking to use LASSO variable selection for a multiple linear regression model in R. I have 15 predictors, one of which is categorical(will that cause a problem?). After setting my $x$ and $y$ I use the following commands:</p>
<pre class="lang-r prett... | g45225 | [
0.021366870030760765,
-0.03493865206837654,
-0.002504084724932909,
-0.021917227655649185,
0.05846743285655975,
-0.041727859526872635,
0.034331776201725006,
0.010558473877608776,
-0.019869603216648102,
-0.013429510407149792,
-0.011194971390068531,
0.035828471183776855,
0.04741791635751724,
... |
<p>I'm working with a Single-nucleotide polymorphism (SNP) dataset with over 2.2 million features and roughly 2000 samples. </p>
<p>I wish to do feature selection on this dataset to reduce it down to approximately ~20,000 features so that I can then use them to train different classifiers for a binary classification p... | g63427 | [
0.019482260569930077,
0.000277490820735693,
0.02352462150156498,
-0.016985399648547173,
-0.022152923047542572,
-0.02580551989376545,
0.015078514814376831,
0.09720198065042496,
-0.01977630704641342,
0.006262566894292831,
-0.014696875587105751,
0.008343285880982876,
-0.003729922929778695,
0.... |
<p>I wish to perform feature selection on a dataset using mRMR but my classes are imbalanced roughly 3:1. Should I down sample the majority class or use the whole dataset? If I use the whole dataset will it select features that are biased towards the majority class?</p> | g63428 | [
-0.010325168259441853,
-0.06332780420780182,
0.008312396705150604,
-0.024048833176493645,
-0.02176870033144951,
0.0246781874448061,
0.026365231722593307,
0.04448522627353668,
-0.01084081456065178,
0.003430725773796439,
0.060736410319805145,
0.01870133727788925,
-0.0303481612354517,
0.04736... |
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