question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
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<p>This may seem like a foolish question, but it is critical for me to have some expert advice on this. </p>
<p>I am doing some research on students' learning levels in India. I am using R software (<code>ltm</code> package) to calculate student scores (ability estimates as per IRT model). </p>
<p>Features of the dat... | g57999 | [
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<p><em>Note that the problem specification has changed since the original posting. Thanks to whuber for helping me better specify the question: in an attempt to make the question general, I had left out several important constraints.</em></p>
<p><strong>Problem</strong>: Let $y$ be distributed Poisson with rate param... | g12866 | [
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<p>With a linear regression defined in BUGS, how should one implement model identification constraints such as having the mean of a group of parameters be zero, or having the group of parameters sum to zero?</p>
<p>EDIT: To clarify, I'm thinking of a model with, say, varying slopes, e.g.,</p>
<pre><code>for (i in 1:N... | g58000 | [
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<p>I have a Gaussian process regression implementation and developed some example data to test the capabilities of those methods. In the posterior calculation one gets the covariance matrix $K$. For some sample data this matrix has a 0 determinant and thus it is not invertible. Can someone see a problem in the covarian... | g12869 | [
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<p>I am using the principle of maximum entropy to fit a density to a given set of samples. I want to generate new set of samples from the approximated density. Is there any way to draw samples from a density obtained by maximum entropy approach?</p> | g41667 | [
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<p>Is there a standard method of dealing with independent variables, where they are samples from a known distribution, and the sample sizes differ from sample to sample?</p>
<p>I'll give an example of what I mean. Suppose your sample consists in $n$ individuals, who have been given 3 different types of test. Let $Z_{i... | g12870 | [
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<p>I need to have <strong>software for detecting dependencies</strong> among data attributes. The simplest example: we have a database table representing results of some social quiz. Columns represent questions; rows, people who passed the quiz. We are searching for different interesting dependencies in the data. </p>
... | g58001 | [
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<p>I'm trying to solve an optimisation problem with stochastic gradient descent with the following properties:</p>
<ul>
<li>It has a very large (1,000,000+ element) parameter vector. </li>
<li>Empirically, there seems to be a single maximum (though I can't prove this) so hill climbing is fine, however the problem is d... | g41670 | [
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<p>Is Koller's "Probabilistic Graphical Models" suitable as a textbook? Or is there another book which is more recommendable as textbook for a master-course?</p>
<p>Disclaimer: cross-posted from quora.com, where I got no answer.</p> | g58002 | [
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<p>I'm having some trouble positing a model in levels for the question below. </p>
<p><strong>Question</strong>: How does the percentage of students born in the United States at the school level moderate the effect of the use of applications or models while learning science (denoted as SCAPPLY) on PISA science scores ... | g58003 | [
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<blockquote>
<p>Find the form of the likelihood ratio test of $H_0 : \lambda = \lambda_0$ against $\lambda\neq\lambda_0$ when $X_1,X_2,...,X_n$ is a random sample from $Ex(\lambda)$. Simplify it as much as possible.</p>
</blockquote>
<p>I've started as follows, where $\lambda_1$ is some alternative parameter</p>
<p... | g49520 | [
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<p>Two towns, $X$ and $Y$. In each town:</p>
<ul>
<li>Pool cross-sections of male and female hourly wages, one from the year before a wage-discrimination policy took effect and one from the year after.</li>
</ul>
<p>Consider the following model:</p>
<ul>
<li>$wage_i=\beta_0+\beta_1after_i+\beta_2female_i+\beta_3X_i ... | g12874 | [
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<p>I have observed values (80 in total) in different measured circumstances (80 in total). I want to test whether my observed values are the result of chance or do measured values affect my observed values. </p>
<p>My problem is that measured values are non-normally distributed and observed values are normally distrib... | g12875 | [
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<p>The world of statistics was divided between frequentists and Bayesians. These days it seems everyone does a bit of both. How can this be? If the different approaches are suitable for different problems, why did the founding fathers of statistics did not see this? Alternatively, has the debate been won by Frequentist... | g27282 | [
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<p>In a Poisson distribution the mean equals the variance. I would like to find a confidence interval of the variance. Is my reasoning below correct? <br>
Using the central limit theorem I construct a 95% confidence interval for the mean $\mu$ <br>
$L \leq \mu \leq U$<br>
$\mu=\sigma^2$<br>
Therefore<br>
$L \leq \sigma... | g12878 | [
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<p>My job is to develop a classification that groups together diagnoses of similar cost and procedures of similar cost, by similar anatomy. For instance a hip replacement would not be in the same group as a heart transplant as they cost different amounts and are not clinically similar. We revise this huge classificatio... | g12879 | [
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<p>I need to study in depth the on/off problem with different approaches: frequentist, bayesian - frequentist hybrid, profile likelihood.</p>
<p>The on/off problem is a counting experiment where you observe $n_{on}$ events when the source is "on" in the time $T_{on}$ and $n_{off}$ events when the source is "off" in ti... | g58004 | [
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<p>I am trying to fit informed prior distributions to data using MLE, and F occasionally provides a best fit (lowest AIC value). </p>
<p>I am starting with only very basic knowledge of probability theory, so I am not even confident that it is appropriate to fit an F in these cases. One of the interesting aspects of pr... | g58005 | [
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<p>I run the cross-validation experiment for a given data set, and tried two different approaches: one is based on SVM, another is based on SVM plus Adaboost. But the confusion matrix for two experiments are exactly the same. I am confused on how to explain this kind of result. Adaboost is supposed to start with a weak... | g12880 | [
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<p>I am not sure how I would analyse this data:
The experiment is looking at the accuracy of emotion recognition in children with ADHD. The children will be asked to identify what emotion a face is portraying (out of 6 expressions; happiness, sadness, fear, anger, disgust and neutral). They will firstly be shown the ... | g41682 | [
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<p>Is ANOVA valid for binomial data?</p>
<p>I have 7 binomial groups and I want to test whether the distributions of all of the groups are equal or whether the distribution of the first group is significantly different than the distribution of groups 2-7.</p>
<p>What tests would accomplish this? I was thinking of jus... | g48882 | [
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<p>I did stepwise regression with my multiple regression model and using AIC as a measure of fit with the <code>step</code> function in R. Afterwards some variables that the stepwise regression did not eliminate was not significant (> 0.05 p-value). Does this mean i have to take out those variables with large p-values ... | g58006 | [
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<p><strong>Edit Note:</strong> Since I posted this question, it has been suggested that I
read some documents and I am still thinking on the subject. I have
added some new understanding as marked between <em>*</em>* asterisks: please do
correct them if I am wrong and add remaining questions.*</p>
<p>I often confuse ... | g37169 | [
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<p>Please see the picture below:
<img src="http://i.stack.imgur.com/pjfW9.png" alt="enter image description here"></p>
<p>I wanted to mark the points that are not consistent with their adjacent points as outlier. What I did was to fit a natural spline fit to 1000 observations (the purple line in the picture is the fit... | g58007 | [
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<p>Suppose I have two vectors, <code>v1</code> and <code>v2</code>, from which I can calculate the angle between these two vectors as a measure of their "distance", using the arccos function, say. For example:</p>
<pre><code>v1 = c(100,200, 500,600)
v2 = c( 50, 30, 10,5)
v3 = c( 10, 7, 30,40)
# pairwise... | g58008 | [
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<p>I analyze real data where assuptions of classical multiway (more than one factor assumed) MANOVA (more than one response variable) are not met (normality, equal variances). Is there any nonparametric variant? Note that Friedman test in only alternative to repeated measures ANOVA, not to more general multiway MANOVA ... | g58009 | [
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<p>I have a survey app (programmed using Ruby On Rails), and I am required to cluster the responses.</p>
<p>I am using a Ruby library called <a href="https://github.com/SergioFierens/ai4r/blob/master/examples/clusterers/clusterer_example.rb" rel="nofollow">AI4R</a> and my code (in the event it is useful...) looks like... | g58010 | [
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<p>Dear crossvalidated community!</p>
<p>I am analyzing a data of a study in which every participant's performance in a memory task was measured twice (once under placebo, once under drug treatment in random order). Moreover every subject was tested in a blood test measuring the level of stable blood marker. I would ... | g58011 | [
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<p>In the field of web analytics, how can one calculate the statistical significance of a metric (for instance Repeat Visitor's). Imagine that we have millions of visitors daily and we are registering each visit, through cookies maybe. We store data per visit/visitor in a relational database and want to show a number f... | g12886 | [
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<p>I'm writing you because i mostly need a general algorithm, or even a hint, which i will afterwards port on my system (an embedded Arduino microcontroller);
I have a set of around 650 samples covering 5 seconds representing a periodic signal but with quite a lot of noise;</p>
<p>I need the frequency of the main/domi... | g12887 | [
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<p>I recognize that there are many types of averages. That said, does "x per y" (e.g. visits per day) always refer specifically to the <strong>arithmetic mean</strong>?</p>
<p>For some context, I saw this recently where someone claimed the cited figure was actually in reference to a median. While I think it might ha... | g41690 | [
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<p>If I have a set of terms each term having a particular frequency associated with it (the number of the times the term has appeared in fixed corpus of papers), then is the following method of significance testing valid?</p>
<ol>
<li><p>calculate the median absolute deviation (MAD) of the GO term frequencies in the g... | g58012 | [
-0.030409492552280426,
0.007309999782592058,
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0.07073864340782166,
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0.046457547694444656,
0.014991878531873226,
0.01958276331424713,
0.00963666196912527,
-0... |
<p>This might look a very silly question to many of you but please answer.</p>
<p>I am interested in generating a volcano plot for my dataset, which has four columns and all values are in log2. column 1 has name while column 2, 3, 4 has values in treated, untreated states and fold change.</p>
<pre><code>DDR1 7.851... | g806 | [
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-0.041325896978378296,
-0.04901929199695587,
0.03475358337163925,
0.023123495280742645... |
<p>I have a 2(truthfulness) x 2 (immediate test) study where I am looking to compare 2 logistic regression models. </p>
<p>Both are classifying the same outcome variable: truthfulness (truthful versus deceptive -- an experimental manipulation where they were told to tell the truth or lie). The independent variable in ... | g58013 | [
0.0213482603430748,
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0.00828274991363287,
0.026995381340384483,
0.03449743986129761,
0.020648904144763947,
-0.028... |
<p>I was reading this <a href="http://www.ee.ucr.edu/~amitrc/cvpr2013_context.pdf" rel="nofollow">paper</a>. However, I have this confusion about the results reported by them. They have given the results in terms of precision and recall. However, their results show that the precision and recall value is greater than 1.... | g58014 | [
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<p>I am a soon-to-be physician. During my studies I have taken a class in biostatistics. I own Martin Bland's "An introduction to medical statistics", which was a required textbooks at the time, and Harvey Motulsky's "Intuitive biostatistics", which I've purchased on my own initiative based on positive reviews on Amazo... | g58015 | [
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<p>I'm trying to fit ST5 distribution for reaction times with GAMLSS. Sometimes mu parameter of the distribution is negative, which is implausible. Is it possible to limit the range of parameter values somehow?</p> | g58016 | [
0.007984012365341187,
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... |
<p>I'm working on a small project in which I try to compare directed a-cyclic graphs. Say I have (directed) three graphs:</p>
<p>1)</p>
<pre><code> X
/ \
/ \
START - X - X - X - X - END
\
\
X
</code></pre>
<p>2) <... | g58017 | [
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0.03455929830670357,
-0... |
<p>I am a bit new to this field. So I needed help in finding out which topic should I focus on for achieving this.</p>
<p>Suppose I have N dependent random variables. I have n samples of each of these random variables.
Now I want to check if the kth sample follows the pattern that is suggested by the previous (k-1) sa... | g58018 | [
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0.04... |
<p>I'm searching for a combination of <code>sensitivity</code> and <code>specificity</code> cost function because i want have more weight for sensitivity ( sensitivity is more impotent for me rather than specificity). After searching i found this :</p>
<pre><code>Final_Cost = ( (Cb/Cg)/( 1+(Cb/Cg) )*Bg + ( 1/( 1+(Cb/C... | g84 | [
0.03278966248035431,
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0.05232468... |
<p>This question is a technical follow-up of <a href="http://stats.stackexchange.com/questions/113780/estimating-n-and-p-for-binomial-distribution-repeated-counting-of-partly-hi">this question</a>.</p>
<p>I have trouble understanding and replicating the model presented in <a href="http://pluto.huji.ac.il/~galelidan/52... | g12892 | [
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... |
<p>I am studying the MDL and found it is sum of model complexity and compressed population complexity. To my understanding, model complexity refers to number of bits to encode the model, which can be computed by number of bits per sample (i.e. log N) multiply by number of permutations. On the other hand, the compressed... | g9367 | [
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0.0397501103579998,
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0.07709984481334686,
-0.016469... |
<p>I have one pending question about finding the transition probabilities in the Markov Switching method. I know that Eviews 8 has this function, but since the latest version I have is Eviews 7, I'm trying to do this method in excel (my God i hope this is possible). My question is, how does one or on what basis does on... | g12894 | [
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0.004544361494481564,
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<p>What formula should be used for sample size calculations for paired ordinal data? Imagine we have an intervention and we want to measure the effect based on before and after measurements of an ordered outcome (say a Likert scale). </p>
<p>I know how to calculate for a t-test for paired continuous data and how to ca... | g58019 | [
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<p>Let's say that we have a 2x5 matrix A where rows correspond to observations and columns correspond to variables from a p-variate Gaussian distribution, and we want to learn the inverse covariance matrix structure. Since n is smaller than p, we cannot invert the sample covariance matrix, and let's say that we have a ... | g58020 | [
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0.0006303166737779975,
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0.023240283131599426,
0.0023836283944547176,
-... |
<p>Some one please share to me the paper to understand how to derive the $E(r)$ and $Var(r)$ for sample coefficient correlation (R) thanks..</p> | g58021 | [
0.01497986726462841,
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0.011022290214896202,
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0.0422... |
<p>How do I define a hypothesis using adf.test (tseries) in R? When I use adf.test, I would like to add a intercept or a trend in the hypothesis, since ADF has three different hypotheses.</p>
<p>I would like to test the following hypotheses:</p>
<p>H0: Random walk
H0: Random walk with drift
H0: Random walk around a t... | g58022 | [
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0.02424095757305622,
0.032337889075279236,
0.03174880892038345,
0.02863... |
<p>The decision function for C-support vector classification is</p>
<p>$sign(wT\phi(x)+b)=sgn(\sum_{i=1}^{l}y_i\alpha_iK(x_i,x)+b)$</p>
<p>How can I modify it to</p>
<p>$sgn(wT\phi(x)+b)=sgn(\sum_{i=1}^{l}y_i\alpha_iK(x_i,x)+b+aconstant)$</p>
<p>that aconstant is a ARBITRARY number </p> | g58023 | [
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0.00767503073439002,
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0.061512626707553864,
0.0484076663851738,
0.... |
<p>I am analyzing a timing circuit I designed, and I need to calculate the probability of a certain event (bit error). For example, I have derived this equation:</p>
<p>$(1 + x) / d < 1 / M$,</p>
<p>where x is a random variable with a normal distribution, d is a random variable with uniform distribution, and M is ... | g58024 | [
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... |
<p>I once heard that </p>
<blockquote>
<p>log transformation is the most popular one for right-skewed distributions in linear regression or quantile regression</p>
</blockquote>
<p>I would like to know is there any reason underlying this fact? Why log transformation is fitful to the right-skewed distribution? How a... | g58025 | [
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<p>If $\theta|\mu \sim N(\mu,\sigma_o^2)$ and $\mu \sim N(0, \sigma_1^2)$ what is the marginalized $P(\theta)$.</p>
<p>$\theta$ and $\mu$ both are nx1 vectors</p>
<p>$P(\theta) = \int P(\theta|\mu)P(\mu)d\mu$</p>
<p>Is it $N(0,\sigma_o^2I+\sigma_1^2A)$?</p>
<p>where A is nxn matrix with all ones?</p> | g12897 | [
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... |
<p>I'm having problem understanding how big sample size is needed for a situation where there are pairs in the before/after groups but these have all multiple data points. </p>
<h2>Problem</h2>
<p>Pose a situation where you have X dart throwers. Each dart thrower have thrown $n_i$ darts for some average $m_i$ points ... | g58026 | [
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0.015068276785314083,
... |
<p>I just finished <a href="http://www-bcf.usc.edu/~gareth/ISL/">"An Introduction to Statistical Learning"</a>. I wondered whether using cross-validation to find the best tuning parameters for various machine learning techniques is different from data snooping? </p>
<p>We are repeatedly checking which value of the tun... | g12898 | [
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<p>I have counts of occurrences of two types of words (A and B) in several texts. What I would like to test is whether the frequencies of occurrence of both types of words across texts is 'correlated'. However, using Pearson's correlation is probably not correct, because my data is not continuous, and in addition the c... | g58027 | [
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0.05498629808425903,
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0.05... |
<p>I'm wondering what is the estimation techniques used in lm(). If it's OLS, how could we perform a log likelihood test by logLik()? What's the difference between lm() and ols(), mle() and other functions?</p> | g58028 | [
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0.029536588117480278,
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0.... |
<p>What is difference(Or relation) between "Latent Class Analysis"and Structural Equation models" and "Latent Growth Curve Models"?</p> | g58029 | [
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<p>everyone here.
I want to use multinomial distribution, but p[] and N are all random. model is correct and data loaded , model compilied, but it can't still run , it says:value of binomial f[1] must be an integer. Is there anyone here know about it? thank you very much .
this is my coda:</p>
<pre><code>model {
fo... | g58030 | [
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-0.00711607513949275,
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-0.015866026282310486,
-0.03905098885297775,
0.000029481401725206524,
0.01572752743959427,
... |
<p>I want to use multinomial distribution, but i don't know the <code>p[]</code> and <code>N</code>. So <code>p[]</code> and <code>N</code> are all random variables. This is my winBUGS code: </p>
<pre><code>model {
for(s in 1:S) {
for(i in 1:E) {
# stochastic part of the likelihood
Sample[s,i] ~... | g58031 | [
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-0.006600461434572935,
-0.054379433393478394,
0.004313309211283922,
0.011272183619439602,
... |
<p>Here goes the question from textbook:</p>
<p>A small restaurant seats 20 diners, and is full every night. The chef knows from previous experience that 40% of the diners order steaks, so she always has 12 in her fridge at the beginning of the evening. If a customer orders steak, what is the probability that he/she w... | g58032 | [
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0.05740237981081009,
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0.031891219317913055,
0.00032527296571061015,
0.... |
<p>Is there a method to understand if two lines are (more or less) parallel? I have two lines generated from linear regressions and I would like to understand if they are parallel. In other words, I would like to get the different of the slopes of those two lines.</p>
<p>Is there an R function to calculate this?</p>
... | g49594 | [
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-0.0121... |
<p><strong><em>Imagine the situation:</em></strong> Mythical Seafolk use holes in the seabed as their burrows. Each hole has two parameters - diameter and depth. <strong>Majority of holes are unoccupied</strong> due to their surplus (n = 235). Occupied holes (n = 15) are (generally) expected to be much deeper and with ... | g58033 | [
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0.06178984045982361,
0.03... |
<p>I have a set of data I ran on a simulation using R with a population size (N) of 1000, sample mean of 64.93, and a standard deviation of 27.61. The distribution is positively skewed and a Wilks-Shapiro test done in JMP shows that the data is not normally distributed. I need the confidence intervals of this data to... | g12904 | [
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0... |
<p>I have a rather open-ended question that I'm hoping people can help me brainstorm for.</p>
<p>Imagine you wanted to design an application to help you put together outfits from your closet.</p>
<ol>
<li><p>To simplify the problem, imagine each outfit needs two components, a top and a bottom.</p></li>
<li><p>Each to... | g58034 | [
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0.03931... |
<p>I have two groups of participants, one group of psychosis patients and one group of controls. All of the participants complete a computer task that has three different conditions.</p>
<p>So, I want to make both within- and between-groups comparisons. Since the differentiating factor between the groups is illness co... | g58035 | [
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<p>I am using famous example from Myers and Montgomery (1995), which is $2^{4}$ factorial design to compare some methods for unreplicated factorial designs concerning active effects and mean squared errors of the predicted values. However, in order to run the analysis, I need to get parameter estimates for full model, ... | g12908 | [
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<p>I have a question concerning <code>mlogit</code> function. </p>
<p>In my experimental design I collect 80 trials for each participant . The subjects are asked to provide an answer by choosing among 4 different alternatives (not ordered). Now, I would like to model the choices of my participants as a function of nin... | g58036 | [
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<p>I have question on evaluating forecasting software with expert systems:</p>
<p>Are there any objective assessment (not from the manufacturer) on expert forecasting software in the literature? </p>
<p>I found two references but both are old:</p>
<ol>
<li>Principles of Forecasting (2001) Armstrong</li>
<li>Forecast... | g58037 | [
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0.0... |
<p>I have a question about the package <strong>leaps</strong> which I am using for model selection. </p>
<p>I would like to compare 4 different selection methods: forward, backward, stepwise and best subset. I used the code below:</p>
<pre><code>library(leaps)
forward <- regsubsets(Response ~.,data = mydata, metho... | g58038 | [
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0.060404617339372635,
... |
<p>I am currently working on neural networks for time series forecasting, my doubt is do we need to account for issues like trend,non stationarity and seasonality while using neural networks as opposed to the box jenkins methodology.</p>
<p>If yes, then how do we account for it . For instance do we need to change the... | g23731 | [
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0.0... |
<p>I have two questions in using <a href="http://www.csie.ntu.edu.tw/~cjlin/libsvm/" rel="nofollow">LIBSVM</a></p>
<ol>
<li><p>The decision function for C-support vector classification is </p>
<p>$$\text{sgn}\left(w^T\phi(x)+b\right)=\text{sgn}\left(\sum_{i=1}^ly_i\alpha_iK(x_i,x)+b\right)$$</p>
<p>How can I underst... | g41728 | [
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0.... |
<p>I have to create a questionnaire that compares the sportiness of Facebook users vs. non-Facebook users. I need to calculate the number of participants that are required so that the result is statistically relevant. Unfortunately I have no idea how I can calculate that. Could you help me?</p> | g58039 | [
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<p>I had to compute the F-test in my ANOVA question and use interpolation if necassary. </p>
<p>The first time, I had to work out the values of $F_{4,90}(5\%)$ which I said was approximatley $F_{4, 60}(5 \%)$ and then did my test and got the right answer. </p>
<p>In the second bit, in my 3-way ANOVA table, when I'm c... | g12911 | [
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<p>I have done a factor analysis on different attributes of different cigarette brands (e.g. how expensive consumers find it, etc.).</p>
<p>Three factors were calculated out of the many attributes after reduction.</p>
<p>Now I would like to do a cluster analysis (euclidean distance and Ward method) on factor scores c... | g58040 | [
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<p>This maybe a stupid question. But I hope someone could help me. I first divide the dataset into training (75%) and test (25%). Then fit a logistic regression model on training data set. When fitting the model, I did some modification on independent variable, such as normalization, transformation stuff. Now I have th... | g12912 | [
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<p>I don't have much experience with statistics and suspect this is a common problem with a common solution. Normally I would just eye-ball the data and call it a day, but at some point you ought to learn the right way to do things. </p>
<p>I have a dataset of about 17,000 areas with a <a href="http://www.postgresql.o... | g58041 | [
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0.0071... |
<p>For a given model: </p>
<p>$y_{ik} = \mu_k + \beta X + u_k X + b_i + \epsilon_{ik}$</p>
<p>where $u \sim N(0, \sigma_{u}^{2} I)$, $b \sim N(0, \sigma_{b}^2 I)$ and $\epsilon \sim N(0,\sigma_{e}^2 I)$.</p>
<p>Assuming the $\epsilon_i$ are... | g58042 | [
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0.008620652370154858,
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0.04102228209376335,
0.005924704018980265,
0.... |
<p>I know how many times a particular factors has been found:</p>
<p><code>values<-cbind(f=c("S1","S10","S3","S4","S5","S6","S7","S8","S9"),count=c(9,8,4,24,20,4,8,21,5))</code></p>
<p>I also have information on the number of times factors are found alone, in pairs, triplets ...</p>
<pre><code>together<-cbind(... | g58043 | [
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<p>I am not clear as to how to assess if a multilevel model fit using <code>lmer</code> satisfies the assumptions of Normality and Homoscedasticity? </p>
<p>I have used the following <code>r</code> code and i find that histogram of residuals and qq plot satisfy the assumption that residuals are normally distributed. B... | g58044 | [
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<p>I have two groups of patients (A and B) with a congenital malformation which might present itself in 3 forms (a or b or c).
Sample sizes are small as you can see, so I think the best test to check whether there's a statistically significant difference between the 3 forms in the 2 groups is a Fisher's exact test in ... | g12914 | [
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<p>I plan to use multiple scaling in R and start with a toy example.
There are two matrices. The first contains 10 observations and the second one contains two replicated rows.
It appears that the repeated rows are projected to different positions.
Intuitively I expect the replicates are projected to (approximately) th... | g58045 | [
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<p>I was wondering if there are any distributions besides the normal where the mean and variance are independent of each other (or in other words, where the variance is not a function of the mean).</p> | g49803 | [
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<p>I know that R's <code>rpart</code> function keeps the data it would need to implement multivariate split, but I don't know if it's actually performing multivariate splits. I've tried researching it online looking at the <code>rpart</code> docs, but I don't see any information that it can do it or is doing it. Anyo... | g12917 | [
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<p>I am trying to use R to conduct community division within my weighted network (based from an association matrix). I tried with igraph but I encountered some problems. I usually use the program Socprog (Whitehead 2009) for my analysis, but as I would like to conduct a community division with Newman modularity (2006) ... | g58046 | [
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<p>when fitting GAMM with R, I would like to know why when the smooth function is linear, the confidence interval is zero around the middle (the dotted lines are crossing each other at the middle)</p> | g12918 | [
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<p>I have different variables (A, B, C, D) which are all ordinal scaled. I have another variable (Z) which is ordinal scaled, too. My sample size is approx. 1.500.</p>
<p>Is it in the statistical sense correct, to calculate the Spearman's $\rho$ for each relationship - (1) A & Z, (2) B & Z, (3) C & Z and s... | g58047 | [
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<p>I'm looking for DBSCAN and OPTICS matlab codes for clustering 'm' pattern in 3D space: the imput is a matrix where the 'm' rows are vectors a the 'n'=3 columns are X,Y,Z axes.
I would also like the result was plotted in 3D graph. </p>
<p>Someone can help me ?</p>
<p>Thanks a lot !</p>
<p>Thank, useful!
But I don... | g12919 | [
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<p>I have a series of patients in whom I have measured the value of a certain blood quantity at several time points. However, the time points vary a lot and the number of measurements range between 2 and 5. I would like to fit a smoothing spline to a graph were I have each patient's blood values on the Y-axis and time ... | g58048 | [
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<p>I'm currently working on a statistical modelling problem in biology. We have cellular measurements of proteins in every cell in a tissue, and I'm using regression analysis to see if a given protein is affected by the protein content in nearest neighbours.</p>
<p>Overall, I'd like a general linear model of the form ... | g58049 | [
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<p>I'd like to run a test for long-run cointegration of two time series: CO2 emissions/capita and energy use/capita in China. My data includes 23 observations for years 1990-2012.</p>
<p>Now as far as I know I have to have <em>I(1)</em> series to test for their cointegration. Nevertheless, unit root tests point out th... | g12921 | [
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<p>I am given a time series data vector (ordered by months and years),which contains only <code>0</code>s and <code>1</code>s. <code>1</code> s represent a person changes his job at a particular a month. </p>
<p><strong>Questions:</strong> What model can i use to determine model how frequently this person change his j... | g58050 | [
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<p>Is this equation: </p>
<p>$$\log{(y)} = a + bx$$</p>
<p>semi-log or log-linear mode (or it is the same thing)?</p>
<p>I have two models: linear (1) and semi-log (2). The values of $R^{2}$, adjusted $R^{2}$, and Standard Error are:</p>
<ul>
<li>Linear: $R^{2} = 0.6780,~\mathrm{adj.}~R^{2} = 0.6513,~~\mathrm{SE}=9... | g58051 | [
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<p>Imagine you would like to use a simple Gibbs sampling to resample from a joint probability distribution which is difficult to model (but you know all the conditionals $Pr\left(X_i|X_1,...,X_{i-1},X_{i+1},...,X_N\right)$, for $i=1,...,N$, hence the Gibbs sampling). At the end, you would have a set of many drawn vecto... | g30579 | [
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<p>It seems that multiple regression is a better way to do analysis. For example,the ANOVA simply gives t-value (or F-value for two or more variables) and does not indicate magnitude of effect. Contrary-wise, the regression analysis indicates both the t-value(s) as well as magnitude of regression coefficients. Does tha... | g12925 | [
0.00966328289359808,
0.006427530199289322,
0.02024691551923752,
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0.0178060345351696,
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0.06684749573469162,
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-0.016153674572706223,
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0.005888679064810276,
0.030318692326545715,
0.075... |
<p>Is it possible to design a probability function P(x) such that the distribution will have a specified kurtosis, K, and skewness, S? I am not otherwise interested in any other properties of this distribution.</p>
<p>P(x) = f(K,S)</p>
<p>...f is some function of kurtosis, skewness.</p> | g58052 | [
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0.09230262041091919,
0.00... |
<p>I'm using a GLM with logistic link function to try to predict Y (0 or 1) as a function of a ton of predictor variables (A, B, C, etc.). Some of the predictor variables (A*, B*, C*, etc.) have been shown in other studies to be significant predictors. I want to show essentially that Y is unrelated to all of the other ... | g12926 | [
0.02560092881321907,
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0.009324413724243641,
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0.036005038768053055,
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0.0... |
<p>I have run my logistic regression model to find out whether the gender of a test name is a predictor of the gender of the word assigned to the test name.</p>
<pre><code>q2.glm=glm(item.gender ~ test.gender, data=q2data, family="binomial")
summary(q2.glm)
</code></pre>
<p>R has returned the following coefficients:<... | g58053 | [
0.011514808982610703,
-0.01941642165184021,
-0.011105280369520187,
-0.038537945598363876,
0.04819285497069359,
-0.01654863730072975,
0.061357803642749786,
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-0.06675287336111069,
-0.035615067929029465,
-0.05946193262934685,
0.03732454776763916,
0.046007800847291946,
-0... |
<p>I initially will apologise for any lack of clarity with regards to this question. I'm posing this on behalf of my sibling who is in the biomedical sciences.</p>
<p>They have done an intervention on a patient. They are measuring the effect of the intervention by looking at test scores (6 questions), and repeating th... | g58054 | [
-0.001591147854924202,
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0.0337199792265892,
0.012989387847483158,
-0.01... |
<p>I have an interaction table with plants species (column) and the number of time each plant has been found to live in each environment (row).</p>
<p>I'd like to know if there is a differential "preference" for plants species to live in different environment. I guess I should run a chi squared test. I'd need some hel... | g58055 | [
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0.043488241732120514,
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... |
<p>In <code>R</code>, there are several packages that calculate Cronbach's alpha. If the data contain no missing values, all packages converge to the same value. With missing data, listwise deletion is a possible way to go (the only option in SPSS or packages <code>MBESS</code> and <code>psy</code> btw). However, listw... | g58056 | [
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... |
<p>I'm new to data analysis and data mining. Often in the papers I'm reading, they use the term "high dimensional multivariate data set." Currently, my task is to detect an outlier and visualize the same from a large complex data set. But how does one find out whether I have a multivariate high dimensional data set or... | g58057 | [
0.024061169475317,
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-0.0011995076201856136,
0.036635007709264755,
0.027036165818572044,
0.0196... |
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