question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I want to implement the EM algorithm to maximize the following censored likelihood when the data is normal:
<img src="http://i.stack.imgur.com/4TQbt.png" alt="enter image description here"></p>
<p>The complete data likelihood is:
<img src="http://i.stack.imgur.com/sVDuZ.jpg" alt="enter image description here">
resu... | g66270 | [
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<p>I am investigating the association between fruiting weeds and fox activity. The hypothesis is that fox activity (sightings per week) is positively correlated with availability of fruit (fruits per square meter). </p>
<p>However there are also independent landscape-scale variations to fox activity which are unpredi... | g25201 | [
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<p>I want to develop a simple character recognition program by implementing a given neural network kind; a simple command line-type is enough.</p>
<p>The radial basis function neural network was assigned to me and I already studied the weight training, input-to-hidden-to-output procedures but I am still doubtful of in... | g66271 | [
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<p>I have two 2-dimensional Gaussian distributions:<br>
$$
D_1 := \mu_1=\pmatrix{x \cr y}, \quad \Sigma = \pmatrix{{\rm var}(x) &{\rm cov}(xy) \cr {\rm cov}(yx) &{\rm var}(y)} \\
D_2 := \mu_2=\pmatrix{x \cr y}, \quad \Sigma = \pmatrix{{\rm var}(x) &{\rm cov}(xy) \cr {\rm cov}(yx) &{\rm var}(y)}
$$
... | g66272 | [
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<p>I have about 80 different groups, each with 3 replicates which I would like to compare against a control having always a value of 1. As I have a low number of replicates and many groups having 2 replicates with 0 values, I would rather do a randomization test than pairwise mann-u test. However, I'm not sure wether I... | g66273 | [
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<p>I am attempting to evaluate and compare the profit factor of different "test runs" of a FOREX trading strategy.</p>
<p>My problem is that, despite an average time between orders of 2hr+, some of these runs can have 20+ orders in a row, every 5 minutes, in the same direction. I need some way to normalize these clust... | g66274 | [
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<p>I'm working at a company developing web applications and due to the load on our testing team that can execute and analyze A/B or multi-variate tests, we're being asked to run "before and after" tests--also called "launch and learn" tests.</p>
<p>With these before and after tests, if we make a change to a web page, ... | g66275 | [
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<p>In my research, I'm summing a bunch of non-independent, not identically distributed random (0,1)-variables $X_1,X_2,\ldots,X_n$ with corresponding probabilities $\pi_1,\pi_2,\ldots,\pi_n$. The resulting distribution is multimodal, and I want to show that the multimodality is caused by the dependence.</p>
<p>In an ... | g37544 | [
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<p>I didn't quite get the Wikipedia explanation here:</p>
<p><a href="http://en.wikipedia.org/wiki/Paired_difference_test#Use_in_reducing_variance" rel="nofollow">http://en.wikipedia.org/wiki/Paired_difference_test#Use_in_reducing_variance</a></p>
<p>I agree that both the unpaired and paired means are the same...then... | g25204 | [
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<p>Sorry, but the emptyness was a bit overwhelming. And this has been stuck in my head since it got asked at Area51!</p> | g45449 | [
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<p>The first thing that comes to mind when comparing some property of two samples is probably the independent samples <em>t</em>-test. Sometimes, people point out that this has the inherent assumption of the <em>t</em>-distribution. Does any one know of a non-parametric alternative to the independent samples <em>t</em>... | g66276 | [
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<p>Thus can we have random variables $X_1 , ... , X_n$ , each with zero mean and unit variance, such that for a sizeable representative sample:</p>
<p>(1) in the least-squares regression equation for $X_1$ against $X_2 ,..., X_n$ , the variable $X_n$ has a large coefficient, and its contribution is rated highly signif... | g66277 | [
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<p>I am a stats novice so I'm sorry if my jargon is a bit off.</p>
<p>I have several large samples of workers in different demographic categories from two different fields A and B. I want to compare the proportion of people in each sample (not of equal size) and try to figure out if there is a difference in the distr... | g25208 | [
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<pre><code>AIC(lm(Fertility ~ ., data=swiss))
[1] 326.0716
</code></pre>
<p>ok, since AIC is calculated as</p>
<pre><code>-2*logLik(lm(Fertility ~ ., data=swiss)) + 2*7
</code></pre>
<p>Why does stepAIC return a smaller AIC?</p>
<pre><code>stepAIC(lm(Fertility ~ ., data=swiss))
Start: AIC=190.69
</code></pre> | g37977 | [
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<p>State-space models are represented by a state equation and an observation equation (or system of equations to be more precise). These equations are parametarized by components including a transition matrix (FF in some notation) and GG respectively.</p>
<p>These component matrices can have large dimensions. Indeed, ... | g66278 | [
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<p>I have a question regarding regression analysis on a dataset were the input values generate different results over time:</p>
<p>e.g.</p>
<pre><code>1 2
2 2
3 5
4 1
2 5
3 8
</code></pre>
<p>How would I go about doing the regression on such a dataset, since the values change?</p> | g66279 | [
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<p>I used <code>regsubsets</code> to find a model with lowest BIC; height is our D.V. , the code I typed is below:</p>
<pre><code>male = read.table(file.choose(), header=TRUE)
mreg = regsubsets(height ~ biacromial + pelvic.breadth + bitrochanteric + chest.depth
+ chest.diam + elbow.diam + wrist.diam + knee.d... | g25211 | [
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<p>I think this is a fairly stupid question, but I just realize that I don't quite understand the term continuity correction.</p>
<p>I use R and found the same syntax <code>correct=TRUE</code> for both <code>chisq.test</code> and <code>mcnemar.test</code>. Are they referring to different continuity correction method? ... | g66280 | [
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<p>I have a dataset including for each subject :</p>
<ul>
<li>22 DV (linears, range [0-1]. These DV are intercorrelated). These measures are volume of different brain regions.</li>
<li>1 main effect to test (disease status; 0,1 or 2)</li>
<li>2 confounding IV (Age of the subject (linear), sex(binary 1 or 2) ; which ha... | g66281 | [
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<p>I am a bit desperate because I am writing my Msc thesis and I am not sure how to organize my data for an SPSS usage. </p>
<p>My research examines the performance of mobile banner campaigns and how the 3 independent variables: Source(in-app or mobile web promotion), Style (animated or static banner) and Size (full ... | g66282 | [
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<p>I noted a strange fact. Let X be a set of Pareto distributed random number with $\alpha$ and $x_{min}$ defined <em>a priori</em>. Now, let $\alpha'$ be the estimated value of the shape and $x_{min}'$ be a new threshold fixed <em>a posteriori</em>. </p>
<p>If $x_{min}'\rightarrow max(x)$ then $\alpha'\rightarrow +\i... | g37995 | [
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<p>I aim to model the temperature variations in two locations in America, example below:</p>
<pre><code>set.seed(10)
RandData <- runif(8760*2)
America <- rep(c('NewYork','Miami'),each=8760)
Date = seq(from=as.POSIXct("1991-01-01 00:00"),
to=as.POSIXct("1991-12-31 23:00"), length=8760)
DatNew <- ... | g45469 | [
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<p>I have two time-series U and V (approximately 300 samples) having values between 0 and 5. I wanted to calculate the (first order) transfer entropy $I_{uv}$ (of U with the knowledge of V) and $I_{vu}$ (of V with the knowledge of U).
Here are the values I got :</p>
<p>$I_{uv}$ = 0.1492 and $I_{vu}$ = 0.1342</p>
<p>S... | g45470 | [
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<p>I have looked at the help (?gbm) and documentation for gbm.object, it only says that </p>
<blockquote>
<p>fit: a vector containing the fitted values on the scale of
regression function (e.g. log-odds scale for bernoulli, log
scale for poisson)</p>
</blockquote>
<p>Is it the OOB estimates ... | g335 | [
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<p>I am very much a novice and really looking for some help. Following advice from a colleague I tried positing this on Stack Overflow but was told I was off topic and should post it here. I'm not trying to get someone to do my work for me - I'm genuinely looking for a bit of help to get started!</p>
<p>I'm hoping som... | g66283 | [
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<p>Each sample in my data set is an $N$-bit bit-vector (say $N$=200). The bits in each sample are not uncorreleated within the sample. </p>
<p>I built a matrix $S_{N \times N}$ with each $s_{ij}$ being the proportion of samples where the $i$-th bit and the $j$-th bit were identical. This is a symmetric similarity mat... | g25216 | [
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<p>I have to analyze this variable which consists of scores given to 3 items (1-9 scale). This "Likert scale" measures "brand commitment" if thats important. </p>
<p>1) Firstly, should I compute 1 new variable that combines the 3 statements (they measure the same latent construct) in order to make it analysable? I und... | g49746 | [
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<p>I am trying to recognize a spatio-temporal pattern in my spatio-temporal input sequence X. The occurrence of the pattern is roughly temporally correlated with another event E1.</p>
<p>For example I have training data of this kind:</p>
<pre><code>...0010010000100001001001000010000001000000010010000... x1 \
...00010... | g25217 | [
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<p>I'm looking for advice to whether or not the following method is good and is standard for calculating PCA of the data. So the examples that I will give will be small. </p>
<p>Given a matrix of $A = [4, 6, 10; 3, 10, 13; -2, -6, -8]$ and Compute the Covariance matrix given as:</p>
<p>$$A = \begin{bmatrix}
10.3&... | g25218 | [
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<p>As an exercise for a statistics course (not homework) I have to test various models for a given contingency table. The contingency table displays data about infant survival rates at two different clinics. There are three variables involved. $X_1$ represents the clinic ("1" or "2"). $X_2$ denotes the kind of care an ... | g66284 | [
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0.014692073687911034,
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0.03993029147386551,
-0.03456712141633034,
0.023330317810177803,
0.03382768854498863,
-0... |
<p>In GARCH model how should I handle outliers?
Just remove it from my dataset and skip to next data entry?</p> | g25220 | [
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<p>I will be conducting an experiment during which I need to measure mental load.</p>
<p>After some research I decided on subjective measurements, as I can't obtain the equipment needed to attempt objective measurements.</p>
<p>I came across the <a href="http://human-factors.arc.nasa.gov/groups/TLX/" rel="nofollow">N... | g66285 | [
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0.003338670590892434,
... |
<p>One of my date column doesn't read in date format, but I need to use the function <code>WEEKDAY()</code> on it.
How can I transform the data format of that column into date format?</p>
<p><strong>UPDATE:</strong>
It is a csv file, following is one of the rows</p>
<blockquote>
<p>01OCT2007,4.92,7.75</p>
</blockqu... | g66286 | [
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<p>I am trying to run an econometric panel data (random effects) model with about 950 observations (so not a small dataset). My data consists of different European public companies and of a few financial statistics of theirs during the last 10 years. However, I am having enormous amount of trouble with the following as... | g49402 | [
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<p>I am attempting to construct a survival analysis in Stata whereby subjects fail if the failure condition is met (Staph) but are also removed from the model once they are over 1100 days old. My current script is -</p>
<p><code>stset new_end_age, id(CPID) failure(Staph==1) exit(time new_end_age>=1100) origin(time... | g37997 | [
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<p>I'm trying to develop a high level model to value events in a marketing conversion funnel.</p>
<p>To take a simple e-commerce example:</p>
<ol>
<li><p>You start with leads in the form of ad clicks. Some % of these ad clicks result in a conversion to an email address. We'll call this 1st step conversion.</p></li>
<... | g66287 | [
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<p>Can we change the acceptance rate in the random walk Metropolis algorithm by changing the parameter of the proposal distribution?</p>
<p>Let the target distribution be $\pi$.
Let $p(x_2 | x_1)$ be the proposal density for a new state $x_2$ at current state $x_1$. The acceptance rate is
$$
\alpha = \min(1, \frac{\... | g66288 | [
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... |
<p>Ted Dunning has a blog post about calculating G2 (aka LLR) using Entropy calculations as components. I found this really intriguing.</p>
<p>Ted's original post:
<a href="http://tdunning.blogspot.com/2008/03/surprise-and-coincidence.html" rel="nofollow">http://tdunning.blogspot.com/2008/03/surprise-and-coincidence.... | g66289 | [
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<p>In machine learning we have the following problem: </p>
<p>Choosing the optimal model (or training):
$$
f^* = \arg\min_{f \in \mathcal{F}} \sum_i l(x_i,y_i)
$$</p>
<p>Is the term <code>model selection" always</code>exactly" referring to to this? Or something else? </p> | g493 | [
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<p>There are many papers that are devoted to efficient inference in graphical models. Though many of these paper don't explicitly talk about the learning (training, etc) problem. For example: </p>
<p><a href="http://videolectures.net/mlss09uk_minka_ai/" rel="nofollow">http://videolectures.net/mlss09uk_minka_ai/</a></p... | g66290 | [
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<p>From some reading I did online, I understand that there are various methods for determining "similarity" used by different clustering algorithms. I am curious if it is good practice to run multiple clustering algorithms/methods (i.e Hiearchical w/ Ward, single linkage, centroid, etc or maybe even K-means) on a datas... | g25235 | [
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<p>I am regressing spreads in yield curves in certain countries, in the chart below, the Spanish 2-5-10 spread, against the Italian 2-5-10 spread.
<img src="http://i.stack.imgur.com/mteWO.png" alt="enter image description here"></p>
<p>I want recent data to count more, so I weight the inputs using a decay weighting s... | g66291 | [
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<p>Can someone provide their thoughts on a structured process one might go through to understand a collection of data.
The scenario is: you've been given a set of data (features and observations - with descriptions) and been told to "tell me what kind of interesting things this data can tell me".
I.e., what are interes... | g66292 | [
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<p>I am investigating a curvilinear effect between X and Y by using a hierarchic regression analysis. To test for curvilinear effects, the squared term for X was computed (I mean center also variable X).</p>
<p>In model 1, the control variables were entered. In Model 2, X (linear) was entered. In Model 3, X (quadratic... | g25238 | [
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<p>Note that the only measure of location in nominal variable is mode.</p>
<p>Is there also any measure of variance?
Obviously, some nominal features are more different than other (color of eyes vs. presence of some rare disease).</p> | g45492 | [
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<p>We conducted this very simple 2x2 Between Subjects Factorial Design Experiment, where the DV were their answers to a classic insight problem. Since there is only one correct answer to the problem, the values for the DV were either 1 if the answer was correct and 0 if it was not. </p>
<p>The results I got was an F-v... | g45493 | [
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<p>I have collected a data from about 200 customers on their brand preference of 5 international fast food chain shops. Each customer was asked to rank all the 5 brands from highest to lowest (5 for the most preferred and 1 for the least preferred brand). The brand rankings will vary from one person to another. </p>
<... | g66293 | [
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<p>I do not want to know if some phenomena in nature have normal distribution, but whether we can somewhere see shape of normal curve as we can see it for example in Galton box. See this figure from <a href="http://en.wikipedia.org/">Wikipedia.</a></p>
<p><img src="http://i.stack.imgur.com/9KJbC.jpg" alt="enter image ... | g45494 | [
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<p>the problem that i have two single server station with no queuing space a customer goes to station 1 if it is available else it goes to station 2 if it is available or it will be lost output from station 1 goes to station 2 if it is empty or blocking occurs and will stay in station 1 til station 2 become available. ... | g66294 | [
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<p>I would like to understand the differences between these tests for one sample median test and when to use each of them.</p>
<p>I have been searching information and this is what I got so far:</p>
<ul>
<li>Sign test (in R sign.test) does not need a probability distribution symmetric but Wilcoxon (wilcox.test) does.... | g30899 | [
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<p>I have a pretty large set of binary-labeled data (~20K rows, ~100 columns). Approximately 20% of the data is "positive" and 80% is "negative". In my case every classification error has the same meaning. Is this misbalance big enough in order to take special measures such as differential weighting and/or differentia... | g66295 | [
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... |
<p>Let $X$ and $Y$ be two independent random variables with respective pdfs:</p>
<p>$$f \left(x;\theta_i \right) =\begin{cases} \frac{1}{\theta_i} e^{-x/ {\theta_i}} \quad 0<x<\infty, 0<\theta_i< \infty \\ 0 \quad \text{elsewhere} \end{cases} $$</p>
<p>for $i=1,2$. Two indepedent samples are drawn in orde... | g66296 | [
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... |
<p>Consider following situation: Study A compares two groups and finds a mean difference with an effect size of d = .8 (p<.05). Study B is a direct replication, and finds an effect in the same direction of d = .3 (p < .05).</p>
<p>From an NHST perspective, there is no single/ simple answer to the question "Does ... | g66297 | [
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<p>Assume $X,Y$ are continuous random variables with finite second moments. The population version of Spearman's rank correlation coefficient $ρ_s$ can be defined as the Pearson's product-moment coefficient ρ of the probability integrals transforms $F_X(X)$ and $F_Y(Y)$, where $F_X,F_Y$ are the cdf's of $X$ and $Y$, i.... | g38216 | [
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0.011777825653553009,
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0.02805599942803383,
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<p>I am analyzing social networks (not virtual) and I am observing the connections between people. If a person would choose another person to connect with randomly, the number of connections within a group of people would be distributed normally - at least according to the book I am currently reading.</p>
<p><strong>H... | g66298 | [
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-0.002379592740908265,
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<p>I'm trying to understand a stochastic process and consecutive events in time.
Should the intersection of two events be on the same sample space, on a combination of <em>simultaneous</em> sample spaces, or a combination of <em>consecutive</em> sample spaces?</p>
<p>I have a question about $A\cap B$. Should the sets ... | g25244 | [
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0.00... |
<p>There is KDD'98 cup data waiting for me to run some anomaly detection algorithms but Weka does not include any of them, natively. Is there any 3rd part package that can be integrated to weka?</p> | g66299 | [
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<p>Can the log likelihood ratio for a simple vs simple hypothesis take a negative value? Since it approximately follows a chi-square distribution for large sample sizes and since a chi-square distribution takes only positive values do we reject or accept the null hypothesis if a negative value is obtained for the log ... | g66300 | [
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0.0... |
<p>I'm doing a masters project where I look for effects of font (fluent, disfluent) on two populations' (control, dyslexic) reading comprehension. SPSS only gives me a significant main effect for population, not font, and no significant interaction between population and font. However, when eyeballing the graph, I can ... | g66301 | [
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0.10491983592510223,
0.01990... |
<p>I have a model with a continuous dependent variable (DV) and 9 independent variables (IVs). My model is a mixed-model, because 7 of the 9 IVs are nested within the two levels of another IV (lets call it X1) which is applied in a repeated-measure design to the same group of subjects (zero at first trial and 1 at the ... | g66302 | [
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0.002931067021563649,
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... |
<p>I would like to reduce the amount of data I have before conducting an analysis. </p>
<p>My data consists of several sets of questions assessing comprehension of various topics (e.g. 4 questions assess comprehension of one concept, 4 questions assess comprehension of another concept and so on). I would like to sum t... | g66303 | [
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0.08071305602788925,
0.02380581572651863,
-0.028493978083133698,
-0.01656586490571499,
0.03380313143134117,
-0.03685339167714119,
0.026385372504591942,
0.05... |
<p>Say I start off with N single cells in a sample. These are then allowed to grow untill there are x progeny from each individual cell.
How many cells must I take so that I have at least one progeny from each the N original cells in the sample?</p> | g29340 | [
-0.014576342888176441,
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0.006108986679464579,
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0.... |
<p>I have an equation like that:</p>
<p>$p(r|s)= \frac{p(s,r)}{p(s)}=\frac{ \sum_{w,c} p(c,s,r,w)}{\sum_{w,c,r} p(c,s,r,w)} $</p>
<p>I am new to probability and I want to learn that how can I write sum formula as multiples of probabilities?</p>
<p><strong>PS 1:</strong> I want something like:</p>
<p>$p(r|s)= \frac{... | g45515 | [
-0.013530259020626545,
0.01767020858824253,
-0.023173131048679352,
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-0.0493386909365654,
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-0.010066146031022072,
0.07902789115905762,
0.03... |
<p>Suppose I have two samples from a population collected from different times, but their distribution looks different (e.g. sample one looks skewed right, while sample two looks bimodal). Can I apply a transformation to sample one, and a different transformation to sample two to make them both normally distributed so ... | g66304 | [
-0.01124147605150938,
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0.021381596103310585,
0.02672247774899006,
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0.0029291424434632063,
-... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/4025/mle-for-naive-bayes-in-r">MLE for Naive Bayes in R</a> </p>
</blockquote>
<p>Hi,</p>
<p>I need the formula representation of maximum likelihood estimate for an example conditional probability distrib... | g49747 | [
0.03947152942419052,
0.000873630226124078,
0.03738284856081009,
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0.024854391813278198,
0.009361028671264648,
0.029383165761828423,
0.03172103688120842,
0.050766... |
<p>One of the assumption of logistic regression is the linearity in the logit. So once I got my model up and running I test for nonlinearity using Box-Tidwell test. One of my continuous predictors (X) has tested positive for nonlinearity. What am I suppose to do next?
As this is a violation of the assumptions shall I g... | g25251 | [
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<p>I am trying figure out what is the difference between Brown's linear model for double exponential smoothing and Holt's model. So the differences can be implemented into a Holt model using if statements. Aside from having alpha for both the trend and smoothing component.</p>
<p>I am having a problem where the foreca... | g66305 | [
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0.017297707498073578,
0.08769471198320389,
0... |
<p>I am currently working on a project where neural networks are used for email categorization. There are two things where I still have some problems understanding the general approach: cross-validation and evaluation using micro/macro averaging. </p>
<p>But first some background: Let c be the number of categories, e.... | g13914 | [
-0.008168419823050499,
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0.... |
<p>I have multiple vectors of letters, in which an entry can appear multiple times. The vectors are of variable length. </p>
<pre><code>ACBDEABAEE
ACDE
ACBDBBDDE
</code></pre>
<p>I want to determine statistically if <code>A</code> or <code>C</code> occurs mostly at the beginning of the list, whereas <code>E</code> oc... | g25253 | [
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0.008981754072010517,
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0.01722238026559353,
0.0066057052463293076,
0.0... |
<p>I am reading a book on probability theory and there is an example to denote conditional independence. A joint distribution is given as follows</p>
<p>$$
p(a, b, c) = p(a) p(b) p(c|a,b)
$$</p>
<p>Now, assuming none of the variables are observed, the point is to show $a$ and $b$ are conditionally independent. They m... | g25254 | [
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0... |
<p>I recently conducted an experiment where people had to decide how much money to take from another participant. People could choose to pick any value between 0 and 100 percent. It turns out that around 40% of the participants decided to take nothing, 40% to take everything, and only 20% took a positive amount differe... | g66306 | [
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<p>I am using the adonis function in the vegan package to determine effects of different environmental factors in forest plant community composition in different regions. I would like to first use adonis to remove the region effect, this is, to fit a model like</p>
<p>adonis_region<- adonis(community ~ region,permu... | g25255 | [
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0.003535269061103463,
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0.02676653489470482,
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-0.0059... |
<p>I found in <a href="http://www.cs.umb.edu/~ding/papers/liICDM2013.pdf" rel="nofollow">this paper (PDF)</a>
a mutual information between groups of variables such as these:</p>
<blockquote>
<ul>
<li>I(X;Y|F)</li>
<li>I(F;Y)</li>
<li>I(F;Y|G)</li>
</ul>
</blockquote>
<p>where F is a set of variables, and G ... | g66307 | [
0.008178859949111938,
0.015245438553392887,
-0.009264959022402763,
-0.006742681376636028,
-0.019831955432891846,
-0.05913432314991951,
-0.045453231781721115,
-0.01948482356965542,
-0.07460710406303406,
0.03487808629870415,
0.0003549622488208115,
0.0485619455575943,
-0.02030908688902855,
0.... |
<p>Suppose I want to estimate the parameter $\mathbb{E}(Y)=\mu \ge 0$ </p>
<p>with </p>
<p>$\mu = a(\alpha)\mu_1(\gamma_1) + \Big(1-a(\alpha)\Big)\mu_2(\gamma_2)$</p>
<p>where</p>
<p>$a(\alpha)\in (0,1)$</p>
<p>Using the usual link-functions for $a,\mu_1$ and $\mu_2$, I'll get</p>
<p>$a(\alpha) = \frac{\text{exp}... | g66308 | [
-0.03558874502778053,
-0.06603912264108658,
-0.025209518149495125,
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0.005800304003059864,
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0.00850074365735054,
0.015187788754701614,
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0.023573145270347595,
-0.01023939996957779,
0.04294055700302124,
0.05570506304502487,
0.0210... |
<p>Currently I'm using libsvm for my one class classification problem. I have 10 samples in my training set, 5 samples in my testing set, both of my training and testing set is scaled by svm_scale, then I use smv_train with the scaled training set for training, and svm_pridict with the scaled testing set for testing. B... | g49748 | [
-0.021740538999438286,
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0.005463952198624611,
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0.039813656359910965,
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-0.02078951708972454,
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0.0312751866877079,
0.019249333068728447,
... |
<p>Is there a unit root test that works with structural change? I only found Zivot-Andrew test but I would try another test, I do not know if the timeseries has a structural change, so I need a test that works with A break at unknown time.</p> | g66309 | [
0.03003755956888199,
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0.040611445903778076,
0.011812997981905937,
0.04718519002199173,
-0.03035591170191765,
-0.02... |
<p>I am trying to analyse (using R) a set of r(theta) data to see if the magnitude (r) is dependent on direction (theta). I have looked at circular statistics but these only seem to deal with the distribution of the observations theta(i) around the circle.</p>
<p>Our null hypothesis is r=1 for all theta, vs its not.... | g25260 | [
0.017736829817295074,
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0.04514225944876671,
0.011745530180633068,
0.04424332454800606,
0... |
<p><strong>N.B.</strong>, The questions require a bit of setup, which I've tried to present abstractly; please feel free to comment on anything that needs clarification.</p>
<p>I have problem where I am predicting the value of several actions for an ensemble of systems that satisfy a particular set of constraints, the... | g66310 | [
0.006217328365892172,
0.016705194488167763,
0.009040934965014458,
0.007377816829830408,
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-0.005190158262848854,
0.05257929861545563,
0.0007120007649064064,
0.09896541386842728,
0.04... |
<p>I'm fitting a linear mixed model by SAS.
There are 596 sectors and 8489 subjects. (each sector contains 10~15 subjects).
Each subject is measured at most 6 times, so the total number of observation is 50043.
SAS code are as follows.</p>
<pre><code>proc mixed data=work.dat2 covtest method=ml maxfunc=1000 ;
class ... | g23819 | [
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0.058177489787340164,
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0.04854673147201538,
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-0.03338748216629028,
0.0007921895012259483,
-0.0036001349799335003,
0.017451774328947067,
... |
<p>In my application I'm receiving a continuous stream of 50 changing numbers, mostly these samples are contained with a nice Gaussian distribution, but now and then there are two+ distributions within the samples. The samples are always positive and within the range of 0 to 1. If there is more than one distribution pr... | g66311 | [
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0.043464627116918564,
0.020342068746685982,
0... |
<p>I will give my examples with R calls. First a simple example of a linear regression with a dependent variable 'lifespan', and two continuous explanatory variables.</p>
<pre><code>data.frame(height=runif(4000,160,200))->human.life
human.life$weight=runif(4000,50,120)
human.life$lifespan=sample(45:90,4000,replace=... | g25262 | [
0.020997263491153717,
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0.02485140785574913,
0.03566815331578255,
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-0.009766585193574429,
-0.04875531792640686,
0.03370939567685127,
0.026261184364557266,
0.01... |
<p>Suppose I have a questionnaire and I ask respondents how often they eat at McDonalds:</p>
<ol>
<li>Never</li>
<li>Less than once a month</li>
<li>At least once a month but less than once a week</li>
<li>1-3 times a week</li>
<li>More than 3 times a week</li>
</ol>
<p>I then correlate these answers with whether the... | g66312 | [
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0.029855109751224518,
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0.08517642319202423,
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0.011608060449361801,
-0.041198648512363434,
0.07134544849395752,
0... |
<p>I'm trying to extend this graph via the provided trendline formula. I'm inserting the formula into the next row and trying to assign X to be the date value, but it doesn't appear to be working. Do I need to apply a function to the date value in order for it to work? Basically I'm trying to predict what June 17th's d... | g38000 | [
-0.025435827672481537,
0.0552670992910862,
0.003283924888819456,
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0.019566183909773827,
0.02918694168329239,
0.07242336869239807,
0.017183... |
<p>Are there any alternative to www.kaggle.com to test abilities for data mining? Or how can I find my own projects to test myself on data mining projects?</p>
<p>Kaggle is a data mining community that constitute some competitions and I am looking for some alternative web site or community to better my data mining and... | g25265 | [
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0.012714420445263386,
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0.02042306959629059,
0.019492974504828453,
0.0509016290307045,
0... |
<p>A random sample of 49 <a href="http://www.kwakiutl.bc.ca/" rel="nofollow">Kwakiutl</a> native Americans reported that they went fishing an average of 68 days each year. Information from a non-native local population showed that they fished an average of 66 days per year (sd = 14). Do the Kwakiutls fish more than the... | g45556 | [
-0.037809595465660095,
0.037188660353422165,
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0.009190058335661888,
0.033155664801597595,
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0.0246904194355011,
0.0275... |
<p>I have conducted an experiment with one group of subjects ($n=14$). I have two within-subjects factors and one dependent variable (called Error). The factor "Type" has 2 levels (Baseline, Operant); the factor "Event" has two levels (Action, Tone). The hypothesis is that there is a significant interaction Type*Event,... | g66313 | [
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0.012271332554519176,
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0.033578142523765564,
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0.018212996423244476,
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-0.009989618323743343,
-0.0049097565934062,
0.020935799926519394,
0.017071986570954323,
0.0... |
<p>I am reading <a href="https://www.otexts.org/fpp/8/4" rel="nofollow">the section</a> about moving average models in Hyndman & Athanasopoulos <em>Forecasting: principles and practice</em>. I am trying to understand the MA(q) model in words.</p>
<p>What is white noise? Is this a differenced series which is normal... | g66314 | [
-0.03510899469256401,
-0.03569110855460167,
-0.01685103215277195,
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0.044838059693574905,
0.0002673884155228734,
0.05278861150145531,
0.048340119421482086,
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0.024618573486804962,
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0.1339844912290573,
0.01151... |
<p>Who are some famous USSR/Russian Statistics/probability academic researchers? Are russian (current Russia and former USSR) strong in this field academically?</p> | g25270 | [
0.040513426065444946,
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0.06515058875083923,
... |
<p>By having a data-set 1000 (900 unlabeled, 100 labeled) record data-set for binary classification, I want to apply a semi supervised algorithm.
The problem is that I don't know how to get values for the ROC plot?</p>
<p>Actually the algorithm tries to find a threshold on a probability value (base on the 100 labeled ... | g66315 | [
-0.03616540506482124,
-0.0008669880917295814,
0.002268248936161399,
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0.03686985746026039,
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0.04489322751760483,
0.08671359717845917,
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-0.015810679644346237,
-0.058789368718862534,
0.07211683690547943,
0.03602034971117973,
-0.... |
<p>I used scipy.stats.linregress function for my dataset. It returns 5 output variables.</p>
<blockquote>
<p>Slope = 0.0453</p>
<p>Intercept = 14.905</p>
<p>r-value = 0.91</p>
<p>p-value = 0</p>
<p>standard error of estimate = 0.00015</p>
</blockquote>
<p>This is the documentation link if anybod... | g49310 | [
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0.027551736682653427,
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0.... |
<p>Is it possible to construct a difference-in-difference regression with only 4 data points, representing <code>Group 1</code>/<code>2</code> <code>pre</code>/<code>post</code> values?</p>
<p>For example, <a href="http://books.google.com/books?id=64vt5TDBNLwC&q=difference%20in%20difference#v=snippet&q=differe... | g25273 | [
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0.034858014434576035,
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-0.03362216800451279,
-0.016214169561862946,
0.03894044831395149,
0.015184671618044376,
... |
<p>I'm studying the task of feature selection on biological microarray, thats is high dimensional dataset (thousands of features) with small number of data points (lees than one hundred). This feature selection serves to support supervised classification task.</p>
<p>What research or algorithm you can recommend me? </... | g25275 | [
0.06676199287176132,
-0.04379592835903168,
0.018576879054307938,
-0.042677346616983414,
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0.03915122151374817,
0.0475265309214592,
0.04... |
<p>Assume that two drugs were tested. The risk of death for drug 1 is $p_1$ and the risk for drug 2 is $p_2$. We define: </p>
<ol>
<li>Risk difference (RD) $RD=p_1-p_2$</li>
<li>The number needed to treat (NNT) $NNT=1/|RD|$</li>
</ol>
<p>If we know the estimated RD as RD* and its standard error as se(RD*), what is... | g37818 | [
0.04274493828415871,
-0.08117040991783142,
-0.007200856227427721,
-0.01667732559144497,
0.047613248229026794,
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0.005266438703984022,
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-0.007982643321156502,
0.008765625767409801,
0.001254381611943245,
0.06615688651800156,
-0.... |
<p>I am interested in spectral clustering so I was looking the scikit-learn code for computing the Lapacian of a graph given its weighted adjacency matrix. </p>
<pre><code>def _laplacian_dense(graph, normed=False, return_diag=False):
n_nodes = graph.shape[0]
lap = -np.asarray(graph) # minus sign leads to a copy
# se... | g66316 | [
0.004600180312991142,
-0.025674737989902496,
0.00007288191409315914,
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0.04089869558811188,
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0.04682302474975586,
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-0.022783728316426277,
0.05231506749987602,
0.0850745365023613,
0.10394927114248276,
0.01053... |
<p>Suppose I have a dependent variable that is a test score, $score^*_{i}$. It has been standardised for both age and gender. I want to measure the effect that a binary variable, say Adoption, has on the persons test score. Will it cause any problems if I include age and gender as controls in the regression of score o... | g66317 | [
-0.021372735500335693,
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0.0019532220903784037,
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0.00739653967320919,
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0.06144065409898758,
0.000178758506081067... |
<p>I have a question on imputation of missing values. A support vector machine does not work with missing values, and in practice i thus hence na.omit the rows / cases with missing values on any of the parameters (e.g. X1 to X10). From a theoretical perspective, can one improve the overall classification performance if... | g66318 | [
0.052745603024959564,
-0.019458787515759468,
0.03751906752586365,
0.008125950582325459,
0.013777000829577446,
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0.002045854227617383,
0.06740259379148483,
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0.03421618416905403,
0.008356868289411068,
-0.02886895276606083,
0.06972165405750275,
0.0863284... |
<p>What are the most useful, popular or important statistical tools and/or methodologies for empirical study of <a href="http://en.wikipedia.org/wiki/Principal%E2%80%93agent_problem" rel="nofollow">'agent-principal problem'?</a>
A simple example will be very useful.
References or book recommendations are highly appreci... | g1124 | [
0.012832899577915668,
0.020632795989513397,
0.009440665133297443,
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0.059059079736471176,
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0.04133805260062218,
0.03714684769511223,
0.05878901854157448,
0.028047319501638412,
0.06573307514190674,
-0.005... |
<p>I'm quite weak in math so I hope you don't mind that I'll try to fully describe how I think when solving this (I think easy) problem. Please tell me if I made some totally invalid assumptions.</p>
<p>I have some <a href="http://www.filedropper.com/data_6" rel="nofollow">data</a> - a slope of a linear regression cur... | g45571 | [
0.00652519054710865,
-0.0016691371565684676,
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0.03591115027666092,
... |
<p>I try to predict the binary, dependent variable $Y$ using a single predictor $X$. $X$ contains some amount of error, due to measurement problems. </p>
<p>I would like to come up with a model for $X$, e.g. assuming normality for errors:</p>
<p>$X \sim N(X_{true}, \sigma)$, where $X_{true}$ is the true, but unobserv... | g66319 | [
-0.020682986825704575,
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0.01007... |
<p>As I was working my way through my book about statistics, I came across the topic of linear regression. During the chapter the author begins with explaining that you want to minimize the residuals in order to make your y = a + bx as good a fit as possible: I do understand this, but halfway the chapter all of a sudde... | g49295 | [
0.045397061854600906,
-0.04093804210424423,
-0.004060722887516022,
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0.07542838156223297,
0.03990161046385765,
-0... |
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