question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Before i start, i should mention i am pursuing my under-grad degree, and hence i have little/basic knowledge about machine learning and statistics.</p>
<p>I've been meaning to make an application which takes a 5-point rating of a particular item based on a few variables.</p>
<blockquote>
<p><strong>Example:</str... | g13036 | [
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<p>I am doing multiple regression on a subset of the NLYS79 dataset, namely a subset containing 540 respondents. And am interested in the significance of race upon earnings. My variables here are: years in school, ASVABC(a measure of intelligence), ethnicity is black, ethnicity is white, female, tenure, hours per week ... | g58114 | [
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... |
<p>Take two problems:</p>
<ol>
<li><p>Andrew is 35, and the probability he will be alive in 10 years is .72. Ellen is 35, for her, .92. Assuming these are independent, what is the probability they both will be alive in 10 years? </p>
<p>Answer: .66, Method: Use the multiplication rule .72*.92 = .66</p></li>
<li><p>Su... | g13039 | [
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<p>Assume you've use a accelerated failure time model to find that the transition of subjects from State A to State B is log-normally distributed with parameters $\mu$ = X and $\sigma$ = Y.</p>
<p>This now needs to be used in a differential equation model as the rate at which subjects move from State A to State B. How... | g58115 | [
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<p>I am using random hot-deck imputation on a repeated measures dataset.</p>
<p>I am tempted to use Rubin's rules for pooling the results of multiple imputation, in particular for regression coefficients. Intuitively it seems the average of the coefficient estimates could be used, but I really don't have any insight a... | g13041 | [
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<p>I am working with a dataset of repeated (x4) observations on 100 subjects.</p>
<p>The outcome is zero-inflated and the data appears to be modelled well by a mixed effects zero-inflated negative binomial model with random intercepts for subjects.</p>
<p>However, approximately 20% of the outcome variable is missing,... | g58116 | [
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<p>I have made these three ordinal logistic regression models:</p>
<pre><code>model1 <- polr(as.factor(carb) ~ mpg, Hess = T, mtcars)
model2 <- polr(as.factor(carb) ~ hp, Hess = T, mtcars)
model3 <- polr(as.factor(carb) ~ drat, Hess = T, mtcars)
</code></pre>
<p>To figure out if the models are a good f... | g13043 | [
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<p>To compare two Bayesian models for the same data, I plotted the fitted values of the first model versus the fitted values of the second model. The plot indicates a perfect similarity.</p>
<p>Relying on this plot, I said there is no significant difference between these two models. However, the difference between the... | g13045 | [
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<p>I have a set of strings of dimension $10,000$. I want to group similar strings together in one group, perform clustering. As string metric, I am using the <code>Levenshtein distance</code>. </p>
<hr>
<p>Simply, with the <code>Levenshtein distance</code> I'll just compute distance between $2$ strings and then by u... | g13046 | [
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<p>Stata allows estimating clustered standard errors in models with fixed effects but not in models random effects? Why is this?</p>
<p>By clustered standard errors, I mean clustering as done by stata's cluster command (and as advocated in Bertrand, Duflo and Mullainathan).</p>
<p>By fixed effects and random effects... | g13048 | [
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<p>I have data in this format:</p>
<pre>
Words,Source,Result
pestology Gomel, cheap, 0
cocreating, cheap, 1
munitioner impersonating nonextinct, cheap, 1
Kolomna, expensive, 1
Enyo's snakemouth, expensive, 0
blueberries backare farriers, cheap, 0
markets rafales, cheap, 0
...
</pre>
<p><a href="http://bit.ly/h2ynoG" ... | g41911 | [
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<p>I have got a strange problem with using functions which are supposed to be in the libraries lmtest & language R (downloaded from cran.r-project recently), namely lrtest() and pvals.fnc() - however, they are not available. I have upgraded my R-version to 2.12.2 but it has not solved the problem.</p>
<pre><code>l... | g58117 | [
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<p>On electronics.stackexchange we had <a href="http://electronics.stackexchange.com/questions/18379/entropy-source-on-microchip-pic24f">a question</a> about constructing a True Random Number Generator. Since the method relies on noise, which isn't deterministic, the only way to test the quality of the RNG seems to be ... | g58118 | [
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<p>I am looking for a self-study site on the web that will allow me to verify my understanding of some basic probability and stats concepts and operations.</p>
<p>What I would like is a site with data and problems (along with the solutions) that I could use to practice my skills (such as regression methods/analysis, p... | g58119 | [
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<p>I'd really appreciate help using Stata to perform a manual stepwise forward logistic regression.</p>
<p>I have 37 biologically plausible, statistically significant categorical variables linked to disease outcome. I need to end up with a final multivariable model.</p>
<p>I've added the first variable (most signifi... | g41916 | [
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<p>While trying to make sense of MDL and stochastic complexity, I found this previous question: <a href="http://stats.stackexchange.com/questions/2828">Measures of model complexity</a>, in which Yaroslav Bulatov defines model complexity as "how hard it is to learn from limited data."</p>
<p>It is not clear to me how M... | g58120 | [
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<p>I am working on a code analyzer application. It is essentially a piece of software that parses and interprets other programs' code and comes up with various metrics, findings, statistics, and ultimately draws performance warnings and re-engineering proposals. It is still in its infancy and what I am currently doin... | g58121 | [
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<p>I'm trying to understand the basic concept of random processes.I already understood that a continuous-time random process is defined by X(¥,t) where ¥ is each element in the Sample Space and t is the time index. </p>
<p>By this definition, we can see the random process as an ensemble of sample realizations ( time... | g41919 | [
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<p>Assume that we have a Markovian environment that generates at every time step an event $A$ with probability $p^*$ and an event $B$ otherwise. Now suppose you are a Bayesian agent that wants to learn $p^*$ from the observations you've made so far. If we let our hypothesis class be $\{H_x\}_{0 \leq x \leq 1}$ and our ... | g41920 | [
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<p>At a nuclear plant great care is taken to measure the employees health.These are the number of visits made by each of the 10 employees to the doctor during a calender year. 3,6,5,7,4,2,3,5,1,4</p>
<p>Assuming the number of visits made by employee has a poisson distribution ,test the hypothesis that the annual mean ... | g33414 | [
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<p>I'm interested in running hypothesis tests for a variety of members of the exponential family with continuous support, for different values of the parameter/s, for a sample of n i.i.d random variables (distributed according to a particular member and parametrization of the exponential family).</p>
<p>In general, it... | g33415 | [
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<p>I will try to explain my data as good as possible.
So we taged 13 different whales with a tag that records time, depth, speed, angle of descent and ascent 25 samples every second.
The normal diving behaviour of these animals is one deep dive of one hour to 1200 meters followed by a series of 3-7 shallow dives of 20 ... | g58122 | [
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<p>Pardon my ignorance, but I really need some help figuring out how to analyze a dataset. Basically the experiment is replicated among 8 blocks, with two treatments (<code>a</code> and <code>b</code>) and a control within each block. Unfortunately (not my design) the experiment is not fully factorial (there are no a... | g48015 | [
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<p>I recently performed an experiment observing ants. For five days I measured the amount of food they ate, 25 ants in the fruits group and 25 ants in the vegetables group. Each ant was kept isolated in its own container. </p>
<p>My hypothesis was that the ant (3 mg in body weight) would be able to eat 20 times more f... | g58123 | [
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<p>If we have to choose between two regression models, one has a
correlation coefficient of 0.95 and the other has a correlation coefficient of 0.75. Is it always the case that the first model is to be preferred over the other if we are interested in optimizing predictive performance?</p> | g58124 | [
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<p>We're designing a trial to test three behavioral interventions (call them A, B, and C) for a health condition. Treatment A is an established intervention and B and C are considered add-ons to A. </p>
<p>We want to test the following contrasts:</p>
<ol>
<li>Outcomes of packages involving Treatment A vs. No treatmen... | g58125 | [
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<p>Suppose we have the following regression, with Sun=0 for partial sun and Sun=1 for full sun:</p>
<pre><code>Plant Height = a0 + a1*Bacteria + a2*Sun + a3*Bacteria*Sun
</code></pre>
<p>And here is the sample output from R:</p>
<p><img src="http://i.stack.imgur.com/JIPvU.jpg" alt="R output"></p>
<p>According to <a... | g13063 | [
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<p>Does anyone understand the difference between weak likelihood principle and strong likelihood principle?</p> | g13065 | [
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<p>I was checking the basic theory of PAC, and I can't understand why the division of the gap between the hypothesis and the class C that we want to learn. <a href="http://www.cis.temple.edu/~giorgio/cis587/readings/pac.html" rel="nofollow">Link</a>:</p>
<blockquote>
<p>An individual $x$ will be classified incorrect... | g13066 | [
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<p>I am trying to find if there is any way to get the true data from multiple noisy versions, but the true data has a peculiar property.</p>
<p><strong>Problem Statement</strong></p>
<p>Consider a matrix $F=[f_1, f_2, ... , f_n]$ where $f_i$ is <code>1984-dimensional</code>. Now, each $f_i$ can be expressed as $f_i=H... | g13067 | [
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<p>I have a task of <a href="http://en.wikipedia.org/wiki/Relationship_extraction" rel="nofollow">Relationship extraction</a>. There are some set of predefined relations in the corpus. I need to train classifier to recognize the type of relation or the lack of relation between every pair of nouns. </p>
<p>I chose to u... | g13068 | [
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0.059626832604408264,
-0.022788317874073982,
-0.00666165491566062,
-0.03373630717396736,
-0.029007181525230408,
0.012383053079247475,
0.... |
<p>I have to test which factors influence game damage in fields. I mapped areas with damage and those without. It was not always possible to map 100% of a field, so there are also areas where it is unsure. Since the "unit" damage is not objective because it is not possible to determine where one ends and the next start... | g58126 | [
0.014336640946567059,
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0.07063798606395721,
0.05625031143426895,
-0.... |
<p>I have three variables (A, T, C) with n= 1083. The Pearson correlations are as below:</p>
<p>A*T= .170 (p<.01)<br>
A*C= .370 (p<.01)<br>
T*C= -.103 (p<.01) </p>
<p>Partial correlation between A and T controlling for C = .225 (p<.01)</p>
<p>I would like to know if the increase in A*T (r= .170) is si... | g58127 | [
0.06378323584794998,
-0.06275676190853119,
0.00798564963042736,
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0.008417080156505108,
0.005109194666147232,
-0.023200999945402145,
0.00860... |
<p>I have used Mean square error value is one of the parameter to analyse.I also noticed that every time i run a design i get different Mean square error value.Not able to identify the reason .</p>
<p>What would be other parameters used to analyse?</p> | g58128 | [
0.049781206995248795,
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0.02213679999113083,
0.014754777774214745,
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0.003465781221166253,
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0.02988356351852417,
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0.10... |
<p>Working in R, how can I specify a mixed ANOVA with multiple between- and within-subjects factors in such a way that it's amenable to adding a covariate in a subsequent analysis? Also, ideally, I would like to use type 3 SS because that's what I'm used to.</p>
<p>I originally did my analysis (without the covariate) ... | g13069 | [
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0.0015099657466635108,
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0.... |
<p>Ten participants have completed a task using two different methods A and B. The first five participants completed the task first using method A then B. The remaining participants completed the same task first using method B then A. The following shows the completion times (minutes) of each method and the order in wh... | g58129 | [
0.010201153345406055,
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0.019934510812163353,
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0.02374495193362236,
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0.04842808097600937,
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0.03569075092673302,
0.006834722124040127,
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0.033... |
<p>as my first post I would like to know if there are SOM implementations (preferably R) available that accept fuzzy input. That is, I have data in which some nominal features are spread out between a number of categories. For example: feature 1 has 5 categories and an observation might have the values (which are actua... | g41945 | [
0.025426629930734634,
0.012663525529205799,
0.024449221789836884,
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0.04077862203121185,
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0.0036450352054089308,
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0.07306945323944092,
... |
<p>For the Theil-Sen estimator I am aware of two principal methods for obtaining confidence intervals:</p>
<ul>
<li>The zyp R-package documentation uses: </li>
</ul>
<blockquote>
<p>The confidence interval on the slope is calculated using the method defined in (Sen, 1968). The confidence interval on the intercept i... | g58130 | [
0.04310023784637451,
0.009231610223650932,
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0.02763896808028221,
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0.06454360485076904,
0.021031025797128677,
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0.017920691519975662,
0.010928024537861347,
0.032620396465063095,
-0.004... |
<p>I just got my hands on the <a href="http://www.electionstudies.org/" rel="nofollow">ANES (American National Election Studies)</a> 2008 data set, and would like to do some simple analysis in R. However, I've never worked with this complex of a data set before and I've run into an issue.</p>
<p>The survey uses oversa... | g41947 | [
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0.04352331906557083,
0.04023822396993637,
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0.01969028450548649,
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0.0003... |
<p>I am examining the effect of a group variable (with five levels) along with other predictors on achievement growth using SPSS Mixed Model. The descriptive statistics showed a consistent pattern on achievement for these five groups across all waves of data collection. That is, the average score of group C > Group E> ... | g13071 | [
-0.03546488285064697,
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0.022167174145579338,
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0.028312379494309425,
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0.01026009302586317,
0.004382900893688202,
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0... |
<p>I have a beta pert distribution of wall heights, with minimum 0.4m, and maximum of 1m.
I also know that along any wall I have either a normal distribution of openings (they are mostly in the middle of the wall) or uniform. </p>
<p>Now, I would like to know the probability of an opening being located at any height ... | g13077 | [
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0.03034484200179577,
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0.0... |
<p>In R, I have an $N \times K$ matrix $P$ where the $i$'th row of $P$ corresponds to a distribution on $\{1, ..., K\}$. Essentially, I need to sample from each row efficiently. A naive implementation is:</p>
<pre><code>X = rep(0, N);
for(i in 1:N){
X[i] = sample(1:K, 1, prob = P[i, ]);
}
</code></pre>
<p>This is... | g58131 | [
0.028105301782488823,
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0.005053521599620581,
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0.0723445788025856,
0.007959527894854546,
-0.01432507298886776,
-0.007473500445485115,
0.03... |
<p>Consider the following data set <strong>train</strong>:</p>
<pre><code>z a
1 1
0 2
0 1
1 3
0 1
1 2
1 1
0 3
0 1
1 3
</code></pre>
<p>with binary outcome variable <strong>z</strong> and predictor variable <strong>a</strong>. </p>
<p>Also consider the following code:</p>
<pre><code>library(caret)
s... | g13080 | [
0.008216560818254948,
-0.04821101576089859,
0.0007908433326520026,
0.05733440816402435,
0.031549885869026184,
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0.06193286180496216,
0.03948405012488365,
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-0.022378085181117058,
-0.05787334591150284,
-0.03200368583202362,
0.05268992483615875,
-0.00... |
<p>I'm working with data from an instrument which is expected a priori to produce Gaussian (normally) distributed data:</p>
<p>\begin{equation}
G = A\exp\left(-\dfrac{(x - \mu)^2}{\sigma} \right)
\end{equation}</p>
<p>The data are normally sparse, with only about 2-3 measurements representing each $G$. In this questi... | g13081 | [
0.01772388629615307,
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0.020588699728250504,
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-0.0215403214097023,
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0.03967662155628204,
0.000484496500575915,
-0.0... |
<p>I'd like to perform logistic regression with some categorical explanatory variables with more categories than just binary 0/1. Is this possible and why?</p>
<p>I am inclined to think that this would give just the wrong result because of the geometric intution, however most opinions online say that explanatory varia... | g13082 | [
-0.018782055005431175,
0.030592424795031548,
0.010728775523602962,
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0.013804323971271515,
0.02042688988149166,
0.062469933182001114,
0.... |
<p>I have data from{ Erne /Soho} for time in unit( hour )on x-axis and the intensity in unit ( 1/s.sr.cm2.Mev/n) on y axis the data so long from 1500 points to 2500 points and the curves look like Gaussian curve i need your help about :</p>
<ol>
<li>Plot and find the fitting , the polyvalu... | g58132 | [
0.02205553837120533,
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0.009579427540302277,
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0.09809941053390503,
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0.09530653059482574,
0.04320358484983444,
-0.03... |
<p>Is there a function the calculates an exponentially weighted covariance matrix in R? </p>
<p>I recall seeing a function some time ago... I cannot turn up any thing in "R Search" or Task View pages.</p> | g13085 | [
0.01409224048256874,
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0.015292135067284107,
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0.07513324916362762,
0.024338191375136375,
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0.03275963291525841,
-0.028751494362950325,
0.01557109598070383,
0.06664887815713882,
0.02744... |
<p>We know that an $m \times m$ random matrix $\boldsymbol{A} = \boldsymbol{H} \boldsymbol{H}^H$ is a (central) real/complex Wishart matrix with $n$ degrees of freedom and covariance matrix $\boldsymbol{\Sigma}$ $(\boldsymbol{A} \sim \mathcal{W}_m (n, \boldsymbol{\Sigma}))$, if the columns of the $m \times n$ matrix $\... | g3009 | [
-0.03960935398936272,
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0.014596697874367237,
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0.028041796758770943,
0.0019213168416172266,
0.004941565450280905,
0.03544861078262329,
-0.043185897171497345,
0.018732018768787384,
0.017298158258199692,
-0... |
<p>This is in followup to a previous question. here :</p>
<p><a href="http://stats.stackexchange.com/questions/18658/neural-network-model-to-predict-treatment-outcome">Neural network model to predict treatment outcome </a></p>
<p>and might be considered to refer to a different aspect of this question:</p>
<p><a hre... | g41964 | [
0.02332521602511406,
0.000886287831235677,
0.014527756720781326,
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0.0497463122010231,
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0.06003054603934288,
-0.019360067322850227,
0.08502575755119324,
-0.0239... |
<p>Both variables (dependent and independent) show autocorrelation effects. Data is time-series and stationary</p>
<p>When I run the regression residuals appear not to be correlated.
My Durbin-Watson statistic is greater than upper critical value, so there is an evidence that error terms are not positively correlated.... | g58133 | [
0.012952743098139763,
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0.004605468828231096,
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0.0546594075858593,
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0.05955795571208,
0.026451436802744865,
0.04371712729334831,
-0.03... |
<p>I have assayed the concentrations of various metal elements in
different anatomic regions of two strains of mice. Now, for each
element, in each region, I want to find whether there
is any difference between the two strains.</p>
<p>The concentrations of the different metals within an animal are
correlated, it is sa... | g58134 | [
0.03224848955869675,
0.01080799475312233,
0.009854630567133427,
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0.05421528220176697,
0.0012826991733163595,
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0.00937782321125269,
0.01712002605199814,
0.05317531153559685,
0.02381012588739395,
-0.0153680... |
<p>I am dealing with electricity prices, and they have 3 know "seasons":</p>
<ul>
<li>Prices during the day follow a pattern;</li>
<li>Prices in the weekend are lower than during the week;</li>
<li>In summer prices are different than in winter.</li>
</ul>
<p>The three effects interact as well, i.e. in summer the dail... | g13090 | [
0.010674338787794113,
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0.014070163480937481,
0.011848358437418938,
0.08877788484096527,
0.0... |
<p>I know that RBM's have been used on image data for pre-training neural nets, but all I can find are RBM's on black and white images. How do you apply them to say 256 grayscale?</p> | g58135 | [
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0.024200284853577614,
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0.06034356355667114,
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0.02934948168694973,
0.04643721878528595,
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-0.05265044420957565,
0.0019326569745317101,
0.020999660715460777,
0.025842299684882164,
0.02... |
<p>I have a sequence of observations that I am representing as proportions:</p>
<pre><code> X1 X2 X3 X4 X5
0.10 0.20 0.50 0.12 0.08
0.07 0.24 0.55 0.04 0.10
...
</code></pre>
<p>The data are coming in as part of a more complicated hierarchical model, for which I need to perform Gibbs sampling. I h... | g13092 | [
0.03885405883193016,
-0.06731721758842468,
0.00512918783351779,
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0.006892013363540173,
0.007715633604675531,
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0.00429143151268363,
0.018432769924402237,
0.002608163980767131,
0.015324... |
<p>I posted this question on the JAGS help discussion, I was seeing if I could get any help here:</p>
<p>I wish to fit a survival model using the data below (first two columns are time points, NA represents censoring, third column is number of samples). Is there a way to weight the likelihood by the sample size?</p>
... | g58136 | [
0.007724901661276817,
-0.016883650794625282,
-0.002653601812198758,
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0.005615627393126488,
0.0002094694209517911,
-0.10447710007429123,
0.07443675398826599,
0.02798478864133358,
-0.014915099367499352,
0.07384317368268967,
0... |
<p>I would like to learn a function $f: \mathbb{R}^n \rightarrow \mathbb{R}$ from data $(x_i, y_i)$ where $y_i = f(x_i) + \epsilon_i$. $\epsilon_i$ can be seen as observation noise; however, it is always smaller or equal to 0 ($\epsilon_i \leq 0$), i.e., the observations are always a lower bound on the true function va... | g58137 | [
0.008699195459485054,
-0.002995259827002883,
-0.017554866150021553,
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0.022329367697238922,
-0.032523881644010544,
0.04241956025362015,
0.002725641941651702,
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-0.05701720342040062,
-0.014170030131936073,
0.03311004862189293,
0.07814586162567139,
0.0... |
<p>I have 2 functions f(t) and g(t).
I would like to find the function s(t) that minimize the error |f(s(t))-g(t)|^2 </p>
<p>Is it possible to estimate s(t) using neural network?<br>
I am new to the field so please try to be clear.</p>
<p>Thanks!</p>
<p>I am using pybrain so a solution related to pybrain would be... | g58138 | [
0.00039931247010827065,
-0.008274594321846962,
-0.002108703600242734,
0.0075064124539494514,
0.039410557597875595,
-0.07847336679697037,
0.0365268811583519,
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0.0025047531817108393,
-0.08411919325590134,
0.021217122673988342,
0.017218880355358124,
... |
<p>If I have generated a set of random data and I wish to measure how well these data fit, e.g. a uniform probability distribution, what are the standard ways to do that?</p>
<p>I am not very experienced with this sort of data processing. One thing that comes to mind is Kullback-Leibler divergence, but there you measu... | g58139 | [
0.020234977826476097,
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-0.05971072241663933,
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0.051834411919116974,
0.... |
<p>I collected 3D velocity data in a river. the recorded timeseries of velocity components $(u,v,w)$ contains turbulent and mean part. Reynolds Shear Stress can be estimated from</p>
<p>$$u=u'+U$$</p>
<p>$$\langle u'w' \rangle=\text{cov}( u'_{t}, w'_{t} )$$</p>
<p>and to extract velocity fluctuat... | g58140 | [
0.04949796199798584,
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0.06285686790943146,
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0.055341936647892,
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0.018197746947407722,
0.022380076348781586,
0.06651532649993896,
-0.018682697787880898,
-0.015382... |
<p>I am trying to use <a href="https://cwiki.apache.org/confluence/display/MAHOUT/Canopy+Clustering">canopy clustering</a> to provide initial clusters for KMeans in mahout.</p>
<p>Is there a way to determine / approximate the values of the distance thresholds T1 & T2 algorithmically? Right now I have T1 = 100 and... | g58141 | [
-0.022201769053936005,
-0.019142957404255867,
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0.0046480861492455006,
0.061674874275922775,
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0.07135213166475296,
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0.01751839742064476,
0.11031103134155273,
... |
<p>I am using Google's visualization API for drawing charts that show files downloaded each day. </p>
<p>I don't know if this is the best idea, but I am thinking of showing download counts on the Y-axis, weekdays (Monday, Tuesday, etc.) on the X-axis, while the legend would show the name of the files. I am facing a p... | g58142 | [
0.0226136464625597,
0.05095122009515762,
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0.022844383493065834,
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-0.018643271178007126,
0.03789280354976654,
-0.03495706245303154,
0.07558247447013855,
0.043... |
<p>I am trying to understand the how to compute the components Variance and Bias of the total Error (e.g. <a href="http://scott.fortmann-roe.com/docs/BiasVariance.html" rel="nofollow">http://scott.fortmann-roe.com/docs/BiasVariance.html</a>).</p>
<p>Assume that I have available a dataset of 1000 observations. Firstly,... | g13096 | [
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0.04880307614803314,
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<p>Cohen's d (or Hedges' g) are often used to compute effect size. They rely on the assumption of homogeneity of variance across samples however. Because of the pooling of variance that they do, I'm also in doubt that they can be useful in the situation when one want to compare groups in generalized linear models with ... | g58143 | [
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<p>I have a dataset size=8755 that has many missing values. If I remove all the missing values, the complete dataset has size=2986. I'm trying to compare the proportion of both dataset in order to understand if those are significantly different or not. For instance compare the proportion of HIV in both groups.</p>
<p>... | g13097 | [
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<p>How does one calculate confidence intervals of cross-validated estimates?</p>
<p>For an epidemiological paper we use cat. and cont. NRI, IDI, and difference in C index for comparison of two Cox models. The reviewer suggested showing only cross-validated estimates <strong>and their 95% confidence intervals</strong>.... | g1435 | [
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<p>How can I get the standard error for odds ratios.
I know how to obtain ORs, either by exp the estimate or by using LSMEANS or SLICE statements. </p>
<p>Unfortunately wasnt able to find the options to have SE for ORs in the output datasets. Only the estimate SE is in there.</p> | g58144 | [
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<p>I have the following data points:</p>
<p><img src="http://i.stack.imgur.com/d0GTF.jpg" alt="enter image description here"></p>
<p>The thin blue line is the aggregated average for each level of X (ages), the thicker blue line is a Loess fit with R.</p>
<p>Now I have two questions regarding this Loess function:</p>... | g58145 | [
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<p>I am attempting a self-study question on uniform distribution but was not able to make sense of the answers provided after taking an attempt.</p>
<p>Appreciate any help and guidiance please.</p>
<p><strong>Question</strong></p>
<blockquote>
<p>An energy company provides electricity with voltage uniformly distri... | g58146 | [
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<p>Suppose I am building a linear model in R. I will be doing standard OLS. I have 10 dummy variables (predictors) that correspond to different regions. 6 of these regions are in California, and the other 4 are in Texas. For example for my Northern California dummy variable is a 1 if the observation comes from Californ... | g58147 | [
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<p>Let's say we have two 2x5 matrices A and B, and a 4x5 matrix C which is generated by concatenating A and B (C=[A;B] in MATLAB representation). Would the sum of the log-likelihoods of A and B under a 5-variate Gaussian distribution with mean $\mu$ and covariance $\Sigma$ be equal to the log-likelihood of C under the ... | g13101 | [
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<p>Currently I am using Random Forest approach for Missing Values Imputation from missForest package in R.</p>
<p>I faced the following problem: the algorithm works much longer than any other imputation approaches like KNN or SVD.
Does anybody know how to overcome this problem or maybe anyone had experience with using... | g58148 | [
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<p>A while ago I read about the flaws people have in assigning probabilities to events based on their beliefs and experiences. For some reason, I started thinking about that today, and realized that I don't recall the main points of the argument, and really want to understand it.</p>
<p>I'll try to state it here as I ... | g58149 | [
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<p>Good evening,</p>
<p>I am working on a self-study probability question as follows:</p>
<blockquote>
<p>A student is taking two courses, math and statistics. The probability the student will pass the math course is 0.70, and the probability of passing the statistics course is 0.80. The probability of failing both... | g58150 | [
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<p>Is it possible to show that the two-parameter Normal distribution has monotone likelihood ratio?</p>
<p>EDIT:</p>
<p>This is actually part of a larger problem. We have a random sample from $\mathcal N(\mu, \sigma^2)$ and are testing:
\begin{align}
Ho\!:\quad&\sigma <\sigma_o , &\mu &\in \mathbb{R} ... | g58151 | [
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<p>I was attempting the following self-study question. After repeated tries, my answers were at best <strong>0.0944</strong>, however, the model answer seemed to be otherwise at <strong>0.1889</strong>.</p>
<p>Will appreciate any pointers as I simply can't figure out even after repeated attempts.</p>
<p><strong><em>Q... | g58152 | [
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0.027590375393629074,
0.03779696673154831,
-0.047... |
<p>For the repeated measures design <em>D.C.Montgomery</em> in his "Design and Analysis of Experiments" <a href="http://rads.stackoverflow.com/amzn/click/0471316490" rel="nofollow">book</a> provides the mathematical / statistical (linear) model: $y_{ij} = \mu + \tau_i+ \beta_j + \epsilon_{ij}$, where $\tau$ is the effe... | g13102 | [
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<p>In EM when you take the expectation:</p>
<p>$E[\log P(y,x \mid \theta)\mid x, \theta']$ </p>
<p>$= \sum\limits_yP(y\mid x, \theta') \log P(y,x\mid \theta)$</p>
<p>I understand this but the following part I don't understand. We know that $x$ is a vector of $n$ independent identically distributed variables. Also y ... | g14418 | [
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... |
<p>So I have fundamental confusion about graphical models. Suppose the following graphical model is given:<img src="http://i.stack.imgur.com/L0C2D.png" alt="enter image description here"></p>
<p>Now the question is do we have the following equality?:
$$p(m_2|\alpha,\beta,y_3)=p(m_2|\alpha,\beta)$$</p>
<p>If so, why e... | g58153 | [
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<p>I have 5 different posterior distributions (mcmc samples) which all estimate the same parameter beta. The 5 models are all obtained from 5 independent standardized datasets but estimate the same parameter. What I want to obtain is a single posterior distribution, combining information of my five original distributio... | g58154 | [
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<p>I have a linear function that coorelates a measurement with error. As values of the measurement increase, so does the mean error. Error is normally distributed. I'd like a way to derive a probability as to how certain my measurement is. How can I do this? One thought was to transform the distribution of error at dif... | g41987 | [
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<p>Let's say I'm constructing a linear model with the intention of predicting automobile sales volume. Let's say that the consumer auto purchasing cycle takes 4 months, and so we'd 'lag' each observation by four data points. So if out data was monthly, out data may end up looking like the following</p>
<pre><code>mont... | g58155 | [
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0.018044307827949524,
0.08950850367546082,
0.01327... |
<p>Not sure if normalize is the correct word to use here, but I will try my best to illustrate what I am trying to ask. The estimator used here is least squares.</p>
<p>Suppose you have $y=\beta_0+\beta_1x_1$, you can center it around the mean by $y=\beta_0'+\beta_1x_1'$ where $\beta_0'=\beta_0+\beta_1\bar x_1$ and $x... | g13106 | [
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0.069... |
<p>I expected that the variance of residuals from a mixed model computed by, for example, lmer should give the same as the residual variance from the summary output.</p>
<pre class="lang-r prettyprint-override"><code># -- Data simulation
group <- rep(letters[1:10], each=10)
groupx <- rep(rnorm(10,0,5), each=... | g58156 | [
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<p>I'd be grateful for any advice about how to do a sample size calculation for the following design. We are interested in the impact of two variations of an intervention on hospital in-patients' perceptions of the quality of the nursing care they received. Therefore, there will be three conditions, including control... | g13110 | [
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<p>I collected data for a discrete probability distribution and I have the pairs (value, probability).</p>
<pre><code>Value Probability
90 0,0033
125 0.0204
180 0.0847
250 0.2516
355 0.4653
500 0.175
710 0.0015
</code></pre>
<p>I have been asked to compute a gaussian fit over th... | g38836 | [
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<p>I have done some research about breakpoints (I am not a statistician) and I found out about the breakpoint, strucchange and segmented packages in R allowing to find breakpoints assuming linear model.</p>
<p>However, I would like to fit a periodic time series with a non linear (periodic) model, and I was wondering h... | g58157 | [
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<p>No matter what class or book I see, the normal distribution is always advocated. I have been trying to find ways to assess relationship between variables for non normal distributions, most of which are exponential. Is there any other method other than spearman correlation to deal with such things?</p> | g41998 | [
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<p>For non-negative matrix factorization with Frobenius norm:</p>
<p>$\min\limits_{U\in\mathbb{R}_+^{m\times r}, V\in\mathbb{R}_+^{r\times n}}||A-UV||_2^2$, $A\in\mathbb{R}_+^{m\times n}$</p>
<p>$r=1$ is a very special case because the optimal solution is given by SVD and there is no need to perform successive minimi... | g58158 | [
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0.076... |
<p>What are the multidimensional versions of the median and what are their pros and cons? I confess this doesn't have a single answer, but I think it is a useful question to ask and will be a benefit to others as well.</p>
<p>How stable it is (i.e. how many samples one needs to get a reasonable estimate of it) is one ... | g58159 | [
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<p>I am analyzing a multilevel model using the software HLM. I am trying to find out more about the <strong>Deviance</strong> statistic that I increasingly see being reported as a measure of the explanatory value/effect size of a model. In general, I know that HLM output reports this statistic and that the smaller it i... | g13118 | [
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<p>I would like as many algorithms that perform the same task as logistic regression. That is algorithms/models that can give a prediction to a binary response (Y) with some explanatory variable (X).</p>
<p>I would be glad if after you name the algorithm, if you would also show how to implement it in R. Here is a c... | g37602 | [
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<p>My question is based on the "<em>forecast</em>" package for R used in <a href="http://rads.stackoverflow.com/amzn/click/3540719164" rel="nofollow">Forecasting with Exponential Smoothing. The State Space Approach</a> - Hyndman et al. 2008. I am using the <code>ets</code> function to estimate the parameters of a mode... | g58160 | [
-0.02715129964053631,
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0.007769376039505005,
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0.08954164385795593,
0.062... |
<p>I got a problem with Exercise 3.1(a). Since there's an example right before the exercise I assumed that X conditioned on M has the same distribution as in the example.
I don't understand their computation of P(X=k), how did that gamma-function appear? (I'm new to the gamma-distribution) and can I use that in my solu... | g58161 | [
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-0.03687145560979843,
0.003975811880081892,
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0.011022399179637432,
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0.027638690546154976,
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0.055703870952129364,
0.047036800533533096,
0.00... |
<p>When teaching an introductory level class, the teachers I know tend to invent some numbers and a story in order to exemplify the method they are teaching. </p>
<p>What I would prefer is to tell a real story with real numbers. However, these stories needs to relate to a very tiny dataset, which enables manual calcu... | g58162 | [
0.026582302525639534,
-0.0032149108592420816,
-0.026268966495990753,
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0.012983862310647964,
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0.03918609768152237,
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0.07065577805042267,
... |
<p>I have designed an idea and am looking for similar approaches in other literature/areas or if I have applied the Bayesian concepts wrongly. Here is a statement of my problem:</p>
<ol>
<li>I am modeling the influence of a single variable X on the odds of a death event. The base chance is 15%.</li>
<li>I am going to ... | g58163 | [
0.004556518048048019,
-0.05486308038234711,
0.004397586919367313,
-0.05213997885584831,
-0.026965707540512085,
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0.061386626213788986,
0.017039118334650993,
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0.... |
<p>I am analyzing an experimental data set. The data consists of a paired vector of treatment type and a binomial outcome:</p>
<pre><code>Treatment Outcome
A 1
B 0
C 0
D 1
A 0
...
</code></pre>
<p>In the outcome column, 1 denotes a success and 0 denotes a fail... | g42003 | [
-0.015565935522317886,
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0.02729189768433571,
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0.042663417756557465,
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-0.0204392671585083,
0.001999315107241273,
-0.004905408713966608,
0.00023913706536404788,
... |
<p>Over the holidays I played a dice game where each player had 3 to 7 d6 to roll each turn. The game gave certain advantages to doubles and triples. I wanted to know the odds of rolling doubles or triples given N dice to understand the importance of "upgrading" to more dice.</p>
<p>My question is really about how t... | g58164 | [
-0.012526865117251873,
0.04675164818763733,
0.008547193370759487,
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-0.03235846757888794,
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0.00609898567199707,
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0.00... |
<p>A naive question perhaps, but one I need an answer to. </p>
<p>I am developing the functional requirements of a machine that needs to accept and process a number of incoming items daily. Any model for future use of this machine is largely hypothetical, and could vary dramatically based on one's underlying assumptio... | g13121 | [
0.013938182033598423,
0.06071311980485916,
-0.015674728900194168,
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0.023723185062408447,
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-0.055987462401390076,
0.019602864980697632,
-0.020286060869693756,
0.040306951850652695,
-0... |
<p>I am running a model selection analysis with a continuous dependent variable and a variety of continuous and categorical explanatory variables. For two of my continuous explanatory variables I am fitting curvature terms as it looks like there is a quadratic relationship between them and the dependent variable.</p>
... | g58165 | [
0.03703988716006279,
-0.030106663703918457,
-0.0004995017079636455,
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0.01696375012397766,
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0.05570691078901291,
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-0.03739522770047188,
0.042356207966804504,
... |
<p>Following the question about <a href="http://stats.stackexchange.com/questions/81000/calculate-coefficients-in-a-logistic-regression-with-r">manually fitting logistic regression</a>, can someone provide the same 'manual' way to fit a ordinal logistic regression with ordered categorical response?</p> | g58166 | [
-0.012290356680750847,
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-0.002950511872768402,
0.01974630355834961,
0.04674011468887329,
... |
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