question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>By looking at the set of relationships within a community, we might discover that we can divide them in groups where people in the same group (a.k.a block or role) tend to relate to the same other groups. This problem is known as "blockmodeling".</p>
<p>[I made a tutorial for the simple case of 1 relation / user:
... | g65085 | [
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<p>I have used the following r code to estimate the confidence intervals of a binomial proportion because I understand that that substitutes for a "power calculation" when designing receiver operating characteristic curve designs looking at detection of diseases in a population.</p>
<p>n is 150, and the disease, we be... | g49620 | [
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<p>I fitted a generalized linear mixed log-gamma model in SPSS with 1 fixed factor (binary), patient ID as a random intercept and a continuous variable as (fixed) covariate. How can I calculate the expected power? I have PASS 11, but I can't find any suitable procedure.</p> | g65086 | [
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<p>just joined this forum I really appreciate the coperative spirit between members.
I have a silly questions but its quite important for me :s
Im wirting a paper about the contribution of foreign banks on the economic growth (Real GDP per capita), a panel data for N=6 countries and T=40 quarters, I was planning to use... | g65087 | [
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<p>when using an unbalanced panel with $N<T (N=6 \:\text{and} \:T=40)$ if we run <code>xtreg</code> and found the panel to be a random effect model (as results of Hausman test estimations), does it have any implications on the other test? Or does it mean we use the coefficient resulting from random effect regression... | g65088 | [
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<p>I have some real data from the past. The data show application demand (for example cpu demand) at a certain time slot. The data looks like this for example: </p>
<blockquote>
<p>3,2,1,5,7,8,9,1,3,12,4,5</p>
</blockquote>
<p>These 12 values show the application demand of cpu in first 12 hours of a day respectivel... | g65089 | [
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<p>I have a training set with about 3000 positive instances and 3000 negative instances. But my test data set is pretty much un-balanced. The positive set only has 50 instances and negative has 1500 instances.This causes the precision very low. Are there any approaches to solve this problem? I use SVM to build classifi... | g49718 | [
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<p>I want to look at depressive symptoms in autism. I have a sample of adolescents and adults with autism spectrum disorders, 49 of whom received the Beck Depression Inventory (BDI) and 6 of whom got the Children's Depression Inventory (CDI; also written by Beck). It is such a small sample that I don't want to throw aw... | g43401 | [
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<p>I'm studying multivariate statistical analysis this semester. </p>
<blockquote>
<p>In our text book, the author said that " A measure of spread is
provided by the sample variance, defined for $n$ measurements on the
first variable as
$$s_{1}^2=\frac{1}{n}\sum_{j=1}^{n}(x_{j1}-\bar{x}_{1})^2$$</p>
</blockqu... | g65090 | [
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<p>I am running time series regressions to estimate the percentage change in quantity to a percentage change in price, with the most basic form being $\ln Q = \beta_0 + \beta_1\ln P + \varepsilon$, where $\ln Q$ and $\ln P$ are the log of quantity and price respectively. My question is if anyone knows about the validit... | g47139 | [
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<p>How would you combine results of model performed on random samples of a very large dataset?</p>
<p>I need to model a very large database in R (~75 million rows) that can not be loaded directly into memory. I am still at the planning phase.</p>
<p>My first idea was to divide the dataset in smaller datasets using r... | g35129 | [
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<p>Since I'm a software engineer trying to learn more stats you'll have to forgive me before I even start, this is serious newb territory...</p>
<p>I've been learning <a href="http://pypi.python.org/pypi/pymc/">PyMC</a> and working through some really (really) simple examples. One problem I can't get to work (and can'... | g65091 | [
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<p>I am TAing a course where students are required to turn in their lab reports formatted like a submission to the journal <em>Ecology</em>. Figures and graphs in this journal do not have the horizontal lines that are the default setting in MS Excel, so I am constantly taking off points because students forget to dele... | g65092 | [
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<p>We're analyzing a bunch of time domain signals, I want to be able to identify an outlying one. </p>
<p>In our results all the signals will either all be reasonably similar, or in some cases, one should be dramatically different. </p>
<p>Here's an example of a set of four signals including an outlier:</p>
<p><img ... | g65093 | [
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<p>I am trying to implement a simple quantile regression in <code>R</code> using <code>JAGS</code>:</p>
<pre><code>n <- 200
x <- runif(n=n,min=0,max=10)
y <- 1 + 2*x + rnorm(n,sd=.6*x)
p <- 0.95
jdf <- list(y=y,x=x,p=p)
params <- c("alpha","beta","tau")
mcmcmodel <- jags.model(file="qreg.jag",data... | g65094 | [
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<p>I have just performed some (very) simple linear regression in Genstat and would like to include a succinct and meaningful summary of the output in my report. I'm not sure exactly what or how much of the information I should be including.</p>
<p>The main bits of my Genstat output look like this:</p>
<pre><code>Summ... | g23542 | [
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<p>I have a dataset of 13k horse races from four different tracks with an average of 11 runners per race. In all, there are 26k unique runners in the data. For each race, I know who came first, second, third, etc.</p>
<p>A horse's <a href="http://en.wikipedia.org/wiki/Form_%28horse_racing%29" rel="nofollow"><em>form... | g37832 | [
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<p>I have C clusters with m elements each. I split the C clusters into a large training set D and a test set T. Hence, each element in D and T has m related elements, so its a cluster.</p>
<p>I want to estimate the variability of the prediction error on T of a regression model that takes k clusters for training (k <... | g65095 | [
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<p>My data has a binary response (correct/incorrect), one continuous predictor <code>score</code>, three categorical predictors (<code>race</code>, <code>sex</code>, <code>emotion</code>) and a random intercept for the random factor <code>subj</code>. All predictors are within-subject. One of the categorical factor has... | g65096 | [
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<p>I am trying to find the correlation between two time series, call them A and B. Let's pretend A has the number of successful advertising campaigns for each month for a company, and B has the company's revenue growth rates (year over year) each quarter. My hypothesis is that the effects of a successful advertising ca... | g23545 | [
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<p>I am trying to wrap my head around False Discovery Rate, and its associated q-value; I am new to this technique, but it seems quite promising for my needs.</p>
<p>One sticking point I keep coming across and cannot seem to resolve is the following:</p>
<p>As best as I can tell, the <b>ordering of q-values can be di... | g65097 | [
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<p>As part of a simulation that I'm working on, I have a probability distribution over $n$ elements, from which I have to sample a <em>set</em> $S$ of size $m$. That is, each element $e \in S$ must be unique [1].</p>
<p>Conceptually I have the following piece of code:</p>
<pre><code>while(S.size < m)
getNextS... | g65098 | [
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<p>We conducted an experiment to determine if type of blood is a main effect or interact with a treatment (2 treatments). The subjects were measured on several hours (5 times). There are 3 subjects by type of blood (these are replicates). Then, we have the effects of TYPE, TREATMENT, TIME.<br>
We are not sure if Time i... | g43424 | [
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<p>I am new to ridge regression. When I applied linear ridge regression, I got the following results: </p>
<pre><code>>myridge = lm.ridge(y ~ ma + sa + lka + cb + ltb , temp, lamda = seq(0,0.1,0.001))
> select(myridge)
modified HKB estimator is 0.5010689
modified L-W estimator is 0.3718668
smallest value of G... | g65099 | [
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<p>Consider an observed time series $\{Y_t\}_{t=1}^T$ and averaged values
$$
Y_t^{(h)}=\frac{1}{h} \sum_{i=0}^{h-1} Y_{t-i}
$$
and what is called an HAR model (this is a specific example)
$$
Y_{t+1}=c+\beta_1 Y_t^{(h_1)}+\beta_2 Y_t^{(h_2)}+\beta_3 Y_t^{(h_3)}+\varepsilon_{t+1}
$$
this can be seen as a restricted $AR(p... | g23548 | [
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<p>As I try to add my PCA ggbiplot a centroid I wonder is the center of the confidence ellipses (X,Y) are the same X,Y coordinates of the centroids?. If so how can I extract them?</p>
<p>Thanks </p> | g65100 | [
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<p>I am fitting a <code>glmer</code> model in the <code>lme4</code> R package. I'm looking for an anova table with p-value shown therein, but I cannot find any package that fits it. Is it possible to do it in R?</p>
<p>The model I am fitting is of the form:</p>
<pre><code>model1<-glmer(dmn~period*teethTreated+(1|f... | g23549 | [
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<p>I have two groups of patients, treated at two time periods. I'm comparing survival. In the later group I have 3 years follow up time. In the early group I have of course access to longer follow up time. </p>
<p>What is correct? </p>
<p>Should I stop follow up in the early group at 3 years (1095 days), i.e. for a p... | g65101 | [
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<p>tanh activation function is nothing but 2*sigmoid - 1. Does it really matter between using those two activation functions. Which function is better in which cases?</p> | g23550 | [
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<p>Are there any examples of complex statistics that are too complex to be computed directly and need simulations (Parametric Bootstrap from a small dataset) rather than computing the statistics from the estimated parametric model?</p> | g65102 | [
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<p>I have two variables <code>X</code> and <code>Y</code> with weights <code>a</code> and <code>b</code> respectively.</p>
<p>Pl. see the link for sample data.</p>
<p><a href="https://docs.google.com/file/d/0B8GenCe8-hoFaGF2NlpTaGJGQWM/edit?usp=sharing" rel="nofollow">https://docs.google.com/file/d/0B8GenCe8-hoFaGF2N... | g65103 | [
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0.033837754279375076,
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0.06... |
<p>It seems like the generally accepted answer to, "How many bootstrap replications should I run?" has been, "<a href="http://stats.stackexchange.com/questions/86040/rule-of-thumb-for-number-of-bootstrap-samples">It depends</a>." It depends seems like a correct answer. Nevertheless, I was wondering whether there migh... | g65104 | [
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<p>This is a more conceptual question, rather than mathematical per se, so I will talk through an example.</p>
<p>To test the proportion of an effect (outcome ~ exposure) mediated by a variable I have performed 2 linear regression analyses;</p>
<ol>
<li>Outcome ~ exposure</li>
<li>Outcome ~ exposure + mediator</li>
<... | g23554 | [
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<p>I sometimes see the following notation, e.g., for the mean of the jth variable over N observations:
$\overline{Y}_{\cdot{j}}=\frac{\sum\limits_{i=1}^N Y_{ij}}{N}$<br>
My question is: What is this little $\cdot$ in the subscript of $\overline{Y}$ called? Interpunct? Middle dot? Centered dot? And when is it used? Is i... | g278 | [
0.03166299685835838,
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<p>I'm running ANOVA for 4 clusters to understand is there any difference between these clusters in terms of their reasons for travel. After I checked Levene test, one of my variables was lower than 0.05, but that variable has F(3,324) = 6.35, p=0.000. my question is, can I rely on this ANOVA analysis or not? because L... | g65105 | [
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<p>I've got a dataset with 3 factor variables with only one interaction. <code>Y</code> is the response and <code>A</code>,<code>B</code>,<code>C</code> are the independent variables. Variable <code>B</code> in particular has a factor that occurs with no other factors, so the design matrix has a 0 in it, leading to an... | g65106 | [
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<p>I am conducting a randomized vignette survey and would like to know if Mann-Whitney is the best test to use .</p>
<p>Participants will be randomized to an identical scenario where a patient deteriorates over 3 time scales over 15 hours. </p>
<p>Group 1 will have the scenario and have access to an end of life treat... | g65107 | [
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<p>I have tested 3 treatment conditions on 7 scenarios where each scenario had 7 trials (each for 20 subjects). After running an ANOVA (<code>aov_res <- aov(value~Scenario*Treatment, data=my_data)</code>),
I get significant effects of <code>Treatment</code>, <code>Scenario</code> and their interaction too (all with ... | g65108 | [
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<p>Does it make sense to compare actual vs. forecast using correlation analysis / see how close $R^2$ is to 1?</p>
<p>Does it make sense to use a paired <em>t</em>-test to test actual vs. forecast to get accuracy of forecast?</p>
<p>I know RMSE is widely used, but I can use RMSE only if I have many models to compare.... | g65109 | [
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<p>I have a linear regression, with 3 covariates, one of which is categorical with 4 categories. I want to determine if second order terms have a significant effect in the model. I would like to ask if it makes sense to square the categorical variable, to study its quadratic effect. </p> | g65110 | [
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<p>I need to fuse multiple surveys using statistical matching, and would like to comply with any best practices. I have studied multiple documents but -- despite the plethora of information -- it's unclear what the best practices are. Specifically...</p>
<p>First, what are the best match keys? I'm considering using r... | g65111 | [
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<p>I need to classify a list of events: each events is either A or NOT A</p>
<p>As it turns out, if the nth event is A, then the (n+1)th event is more likely to be A.</p>
<p>How would I go about adding this probabilistic component into a supervised learning model? </p>
<p>Thanks!</p> | g65112 | [
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<p>I'm used to thinking about meta-analyses in terms of evaluating the impact of an IV on an outcome of interest (ex: relationship between a teacher's level of self-confidence and student outcomes), and I'm used to calculating r (or using t-test, F or p-values, etc to calculate g or d and then converting that to r). </... | g65113 | [
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<p>I am trying to do statistical analysis on data where my x axis is categorical. I have five different treatment groups on the x axis. My y axis is continuous (mRNA levels of a certain gene responding to the different treatment groups). I was planning on using one-way ANOVA and post-hoc testing. </p>
<p>However, I ha... | g65114 | [
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<p>I have 2 categorical independent variables (industry & location) and 1 continuous dependent variable (performance metrics). I need to find significantly different industries by mean performance metrics in each location separately. Sounds like a task for ANOVA, but running one-way ANOVA for each location separate... | g65115 | [
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<p>why does L2 produce smooth, non-sparse weights, as opposed to L1?</p> | g49719 | [
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<p>What is the best way to know the best selection method for our logistic regression model ?</p>
<ul>
<li>Forward Selection</li>
<li>Backward Elimination</li>
<li>Step-wise Selection</li>
<li>Full Model.</li>
</ul>
<p>I am running logistic regression in SAS EG. </p>
<p>I have tried running each of them for the data... | g49720 | [
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<p>I have an abundance of small data sets with right-censored data. There are different groups in each data set and I'd like to get confidence intervals for the regression parameters. Each data set has 3-6 replicates per group and the percent censoring is usually small (say 5%) but not always. </p>
<p>I can't see to f... | g65116 | [
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<p>I have an issue I cannot solve myself and hope I can get some pointers here:</p>
<p>I have a RCB design with 10 tree species each replicated 5 times in 5 blocks. I classified all species according to their height and assigned them to 3 groups (A, B and C). Then, I chose 2 species from each group and take my measure... | g65117 | [
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<p>I have to forecast a time series in R of a Internet network traffic bitrate.
The data are in file <a href="http://www.forumaltavilla.it/joomla/datitesi/dati.dat" rel="nofollow">http://www.forumaltavilla.it/joomla/datitesi/dati.dat</a> and the sampling time is every 0.05 seconds.
Now, i want to use HoltWinters foreca... | g23561 | [
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<p>At the bottom of page 9 in <a href="http://statweb.stanford.edu/~jhf/ftp/trebst.pdf" rel="nofollow">http://statweb.stanford.edu/~jhf/ftp/trebst.pdf</a>, the author relates the final function $F_{m}$ to $P(y=1|x)$ via the logistic function, and suggests classifying a data point as positive when $P(y=1|x) > P(y=-1|... | g65118 | [
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<p>I have several histograms which I would like to compare to one reference histogram to see which one is the most similar to the reference in terms of the shape of the distribution. </p>
<p>Kologorov-Smirnov gives unhelpful answers as often the largest difference in y-value is not indicative of worst fit. From inspec... | g65119 | [
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<p>I have a huge multilevel longitudinal observational data of the concentration of certain chemical collected at various sites over 10 years (1990-2010). Sites are classified into different type of sites as A, B, and C. In the dataset year variable is coded as 1990,1991, 1993 etc. At one year, there can be many sam... | g29057 | [
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<p>I am preparing a presentation about multiple regression. Most of my sources seem to equal unstandardized coefficients in multiple regression with the semipartial correlation of that IV with the DV. But one book says there is a slight difference:</p>
<p>both terms have the same enumerator, but the differ in the deno... | g65120 | [
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<p>I estimated a Transfer Entropy value TE(XY). Now I want to establish the statistical significance of the estimated value. Therefore I used the method of shuffled surrogates to estimate a shuffled surrogate TEss(XssYss) which should be close to zero because there should be no casual relationship between the shuffled ... | g65121 | [
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... |
<p>I want to arrive at a measure that tells me how much of the total variance of a variable is due to the differences between units (between variance) rather than due to differences across time for the same unit (within variance). I guess the measure I'm looking for is called 'Variance Partition Coefficient (VPC)'.</p... | g65122 | [
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<p>I want to find a weight that minimizes an averaged cross validated misclassification score from an $L_2$ logistic regression classifier. Obviously, the search space for the weights should be bounded below by zero, but are there any other rules of thumb for selecting weights to test? Should I search in the log space?... | g46426 | [
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0.028500139713287354,
0.034712910652160645,
... |
<p>Find the limiting distribution of $\sqrt{n} \left(\sqrt{\bar{X}} -1 \right) $ if $\sqrt{n} \left( \bar{X}-1 \right) \to N(0,1)$. Can you please check my work below?</p>
<p>In principle, the Delta method should be of use here. We know that according to that particular method if $$ \sqrt{n} \left( X_n -\theta \right)... | g65123 | [
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0.030755091458559036,
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... |
<p>It seems (I have a vague notion) that there is some similarity between the two measures. Alternatively stated, there is certain relationship between the two? could you please clarify the idea</p> | g65124 | [
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<p>In the context of machine learning and pattern recognition, there's a concept called <a href="http://en.wikipedia.org/wiki/Kernel_trick">Kernel Trick</a>. Facing problems where I am asked to determine whether a function could be a kernel function or not, what exactly should be done? Should I first check if they're o... | g65125 | [
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0.06038563698530197,
0.007961... |
<p>I have recently installed R-essential and the "psmatching" program. All went well, until I performed (actually tried to perform) the analysis.</p>
<p>Basically, I have a cohort of patients, divided into two groups, and I try to compare their survival. I was recommended to perform a propensity score matching analysi... | g65126 | [
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-0.003296898677945137,
... |
<p>I created an algorithm for forecasting time series (mix of ML methods). Now I need some data so I can compare my results with others and assess accuracy. Unfortunately, I can't find anything like the MNIST dataset for digit recognition task (ie. table with the best results and used methods: <a href="http://yann.lecu... | g45214 | [
0.03800901770591736,
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0.0005227780784480274,
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0.011215116828680038,
0.01322896871715784,
0.09897040575742722,
... |
<p>This might be a basic question, but I am analysing the diversity of floral traits in plant communities. Some of my data are reflectance spectra. I want to reduce the complexity of these data by doing PCA on the spectra, and then include those PC axis scores in another PCA including other morphological traits. </p>
... | g16845 | [
0.025352925062179565,
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0.01938735693693161,
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0.012722407467663288,
0.03430767357349396,
0.02133885584771633,
0.003311063162982464,
0.002050... |
<p>I am trying to apply the lasso or ridge regression to my data set for the feature selection, <em>but different random seeds produce different models</em>. What is a good or universal way to obtain the final model? </p>
<ul>
<li>Fix a seed, OR </li>
<li>combine models from different seeds (if so, then how should I c... | g65127 | [
0.03596006706357002,
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0.01026223599910736,
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0.0364207923412323,
0.08530804514884949,
0.02632... |
<p>Why the peak of density plot in the data given below is higher than 1? Shouldn't it be below 1?</p>
<pre><code>x = c(0.43,0.71,0.6,0.56,0.14,0.38,0.71,0.33,0.09,0.8,0.62,0.33,0.12,0.6,0.4,0.56,0.33,0.75,0.4,0.43,0.75,0.75,0.12,0.09,0.54,1,0.46,0.33,0.33,1,0.5,0.52,1,0.25,0.2,0.71,0.6,0.54,0.75,0.67,0.2,0,0.33,0.73... | g49345 | [
0.055212464183568954,
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0.0006605605594813824,
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<p>How can I prove that pointwise product of two kernel functions is a kernel function?</p> | g65128 | [
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... |
<p>What is the probability of taking 15 free throws in a game and making 10 in a row given that each shot has a 50% probability of going in?</p>
<p>I have simulated this problem but I also want to confirm the results with an analytical approach.</p>
<p>This appears to be a problem that fits with the binomial distribu... | g49367 | [
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<p>I am doing an introductory course in statistics and I'm struggling with one question in particular. </p>
<p>The question is:
Suppose two people each have to select a number from 00 to 99 (therefore 100 possible choices).</p>
<p>(a) The probability that they both pick the number 13 is:</p>
<ol>
<li>2/100</li>
<li>... | g65129 | [
0.04156546667218208,
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<p>If you have unequal sample sizes in cells, then the order in which you enter model terms changes your results for sequential or Type I SS. The first variable to enter the model is allocated its unique variance plus the variance shared by the second variable, then the second variable gets only its unique variance.</... | g43457 | [
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<p>When calculating the confidence interval for the population mean and the variance is unknown, I take it that you have to use the t-distribution.</p>
<p>However, do you use the one-tailed or two-tailed test values for $\alpha/2$?</p> | g65130 | [
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<p>It seems non-convexity of loss function is not such a problem for <a href="http://scholar.google.fr/scholar?cluster=11408949777228074694" rel="nofollow">boosting with a normalized sigmoid loss function</a>. Do you know any further work showing better results with this kind of boosting than <a href="http://en.wikiped... | g23570 | [
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<p>I need to compare two categorical tests as follows:</p>
<ul>
<li><p>A size $\alpha$ Pearson's test rejects $H_0$ if $Q(x) = {(x_1 - np_{01})^2 \over np_{01}(1 - p_{01})} > F_1^{-1}(1 - \alpha)$</p></li>
<li><p>A size $\alpha$ binomial ML test. Rejects $H_0$ if $T(x) = {(x_1 - np_{01})^2 \over n(x_1/n)(1 - x_1/n)... | g23571 | [
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-... |
<p>Lets say I have a website which gets 100 hits per day (mu = 100). Yesterday my website got 130 hits (x = 130). If I assume a Poisson distribution, then the probability of getting 130 hits is:</p>
<pre><code>> dpois(130, 100)
[1] 0.0005752527 # about 0.06%
</code></pre>
<p>So this tells me that getting 130 hits ... | g13821 | [
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<hr>
<p>EDIT NOTE: I'm mostly concerned with linear regression with unconstrained y-intercept, but reading about constrained y-intercept, if relevant, is also helpful.</p>
<hr>
<p>I noticed that for linear regression, the coefficient of determination (R-squared) can be as high as 1 (if the linear regression fits the... | g23573 | [
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<blockquote>
<p>In a sample of 200 male drivers, 130 said they used seat belts. In a
sample of 300 female drivers, 163 said they used seat belts. Test the
claim that men are more safety conscious than women, at a significance
level 0.01. What will be your conclusion if you test whether there is
a gender diffe... | g65131 | [
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0.011981776915490627,
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0.02533494308590889,
0.0... |
<p>I do not know if this has been asked before, but I do not found anything about it. My question is if anyone can provide a good reference to learn how to obtain the proportion of variance explained by each one of the fixed and random factors in a mixed-effects model.</p> | g65132 | [
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<p>I was wondering if there is a free tool to build a decision tree in interactive fashion like in SAS Enterprise Mining. I'm used to work with Weka. But nothing fits to my needs. I would like that before splitting every node, the program asks to user which attribute (maybe from a list of the "best" attributes) to choo... | g65133 | [
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0.06344325840473175,
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0... |
<p>I have a series of timestamps (expressed as Unix time) representing certain dates when an event happened. I want to analyze these timestamps to find information such as:</p>
<ol>
<li>average time between events</li>
<li>find out if the timestamps are evenly distributed or tend to group in periodic clumps</li>
<li>i... | g29065 | [
0.02141057699918747,
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0.017347542569041252,
0.0031051579862833023,
0.034712135791778564... |
<p>I've collected data on accuracy of recognition of images. Accuracy is a score out of 2 with points 0,1,2.. participants can score a 0.</p>
<p>I am aiming to use a parametric test (ANOVA mixed design) to analyse data between groups. </p>
<p>I'm confronted with issues of normality with such a limited range. My query... | g65134 | [
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0.014841682277619839,
... |
<p>I have the following problem.
I'm reading through the Gaussian Process book <a href="http://www.gaussianprocess.org/gpml/chapters/RW2.pdf" rel="nofollow">http://www.gaussianprocess.org/gpml/chapters/RW2.pdf</a>. In the bayesian linear regression it is suggested to use the Gaussian prior over the parameters. For the... | g716 | [
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0.056014906615018845,
0.009532112628221512,
0.04584037885069847,
... |
<p>From what I understand, the null hypothesis for One-way ANOVA is: </p>
<ol>
<li>There is no difference in the means of factor A</li>
</ol>
<p>The null hypothesis for Two-way ANOVA is: </p>
<ol>
<li>There is no difference in the means of factor A</li>
<li>There is no difference in means of factor B</li>
<li>There ... | g23577 | [
0.0046216947957873344,
0.034652870148420334,
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0.05199279263615608,
0.0012723339023068547,
0.003440752625465393,
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0.002770419465377927,
0.04807271063327789,
0.... |
<p>Imagine you have a matrix, <code>M</code>, of <code>n</code> input variables and <code>m</code> values per variable. There's also a <code>X</code> vector of one output variable with <code>m</code> rows.</p>
<p>Now you want to develop a procedure to obtain future "reliable" estimates of output variable <code>X</code... | g65135 | [
-0.01131518092006445,
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0.037116602063179016,
0.0405752994120121,
0.013784072361886501,
-0.0... |
<p>I'm attempting to find a way to judge the similarity of various sample groups, based on the strength of correlation to a set of variables within each group, and I'm trying to figure out if what I'm doing is statistically valid, and if there's a better way.</p>
<p>For example, I have 63 geographic regions. I have a... | g65136 | [
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0.06315857917070389,
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0.03962215781211853,
... |
<p>I was evaluating a research paper in which the authors have 23 male participants and 117 female participants. They have applied t-test to calculate Gender differences and have even concluded on significance of the difference. I am not sure when the groups are so markedly difference in terms of their size, we can use... | g49721 | [
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0.0259301345795393,
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0.009171310812234879,
... |
<p>I have all the data and an ODE system of three equations which has 9 unknown coefficients (a1, a2,..., a9).</p>
<pre><code>dS/dt = a1*S+a2*D+a3*F
dD/dt = a4*S+a5*D+a6*F
dF/dt = a7*S+a8*D+a9*F
t = [0 1 2 3 4 5 6 7 8 9 10 11]
S = [17110 18045 19898 22069 23621 24414 24294 24433 24302 23107 22074 21162]
D = [1157.33... | g65137 | [
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0.051259685307741165,
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0.046386685222387314,
0.09698229283094406,
-... |
<p>OK the problem came from an AI course that I attended this year. You can find the problem description <a href="http://dd2380.csc.kth.se/hw/hw3/assignment/" rel="nofollow">here</a></p>
<p>In short we have a number of birds in the sky that we need to shoot down.</p>
<p>In the main problem there are 90 white birds, 2... | g65138 | [
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0.001462266081944108,
0.05988728627562523,
0... |
<p>Say I fit a multiple regression of p explanatory variables. The t-test will allow me to check if any single one of those is significant ($H_0: \beta_i = 0$). I can do a partial F-test to check if some subset of them is significant ($H_0: \beta_i=\beta_j=...=\beta_k=0$).</p>
<p>What I often see though is that someon... | g23582 | [
0.004349191673099995,
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0.01951739564538002,
0.07... |
<p>In time homogeneous discrete Markov chains we take a set period for a single transition. In examples we see sometimes depending on the examples the transition period being a a month a week etc. I'm wondering whether anything can be said on what happens during a transition (for example if a transition period is one m... | g65139 | [
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0.016715051606297493,
0.01514844223856926,
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0.0033104338217526674,
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0.05723320320248604,
0.04... |
<p>My question is about a binary decision tree (binary to integer).</p>
<p>Is there any problem if the conditions defined on a <strong>same variable</strong> ex. <strong>x1</strong>?
I mean when i define the variables for my tree, can I choose:</p>
<pre><code>if(x1>3)
then
if (x1>4)
then ....
else
... | g47233 | [
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-0.014433545060455799,
0.05798228457570076,
-0.03699477016925812,
0.0540... |
<p>How many trees would you suggest to pick to perform recursive feature elimination (RFE) in order to optimize Random Forest classifier (for binary classification problem). My dataset is very high-dimensional (> 200 000 features), and I usually select ~ 10 000 trees while running a classification without feature selec... | g26938 | [
-0.028981192037463188,
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0.027136363089084625,
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0.025375498458743095,
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0.04647448658943176,
0.01892154850065708,
0... |
<p>Say, I have a vector v = {5,2,8,9,2}</p>
<p>I then want a weighted mean where values of v closer to a given number (which could be mean(v), or something else) are weighted more (proportionally). So 5 (or v(1)) should be weighted more heavily than 9 (which should be given low weight).</p>
<p>The given number could ... | g23585 | [
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0.02695358358323574,
0.... |
<p>The feedback I received from my initial post seemed to indicate that my question was ill-posed. Hence, I would like to clarify what I am doing and how I hope to achieve it.</p>
<p>I'm running some simulations on models with a material parameter $g(x)$ whose values, according to the literature I've read, are log-no... | g23586 | [
-0.00654203537851572,
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0.024767767637968063,
... |
<p>I have a random variable $x$ with $E(x) = \mu$ and PDF $f(x)$ and CDF of $F(x)$.</p>
<p>Is there any way to represent the $E(x|x<\bar{x})$ in terms of $\mu$ and $f(x)$ or $F(x)$? </p>
<p>i.e. to write the following integral only in terms of $\mu$, $f$ and $F$:
$$
\int_{-\infty}^\bar{x} x f(x) dx
$$</p>
<p>Th... | g65140 | [
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0.018996428698301315,
0.009536161087453365,
0.014544925652444363,
0.0027894978411495686,... |
<p>I am a newbie in R programming. I think for most of you my question is a rather simple one. My regression problem is as follows: </p>
<p>I have a dataframe containing several numerical attributes and several factors, which are different in the number of levels. I split the dataset in a training set and a test set. ... | g65141 | [
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0.02... |
<p>Consider a situation where two independent sources, $s_1$ and $s_2$ are giving probability estimates regarding the occurrence of a event $e$.</p>
<p>I tried to model this as a bayesian network but that didn't get me far. Then I came across Dempster–Shafer theory and the body of research regarding belief functions a... | g65142 | [
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<p>The short version of my question is: How is it possible to control for a confounding variable that has a Dirichlet distribution?</p>
<p>Suppose I have electoral and census data for a large set of cities. In this simplified example, say, there are two parties (Liberal and Conservative), and that someone is either co... | g43489 | [
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-0.017878513783216476,
0.0876326858997345,
... |
<p>Where can I find the code (Matlab or R) for the block-regularized Lasso problem defined as follows:</p>
<p>$\min_{B} \| Y-XB\|_F^2 + \lambda \|B\|_{1,2}$</p>
<p>where $Y$, $X$, and $B$ are matrices.</p>
<p>This is a basic problem in multivariate regression and it's strange that I cannot find any code for it onlin... | g4706 | [
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0.02136468142271042,
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0.09102906286716461,
0.03139038011431694,
0.005... |
<p>This is a terminology question.</p>
<p>Is $T(X)$ or $T$ a statistic? $X$ is a random variable, and $T$ is a measurable mapping.</p>
<p>I ask this because, I want to know how to say the distribution of $T(X)$ completely in words.
$T(X)$ is the composition of $T$ and the random variable $X$, and i call the distribu... | g23598 | [
0.013206789270043373,
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0.0013904119841754436,
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0.0457499623298645,
0.... |
<p>I'm using a Poisson regression to model count data (number of orders). My observation lengths are different, so I tried to include an offset variable in the model. The problem is that when I estimate length variable coefficient instead of fixing it to 1, model's quality becomes substantially better. But I'm not sure... | g65143 | [
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<p>I am looking for reference for a high order MA model. Shall be extremely grateful for a reference.</p> | g23601 | [
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0.06178794056177139,
... |
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