question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>The coefficient of determination is $$r^2 = 1 - \frac{SS_\text{res}}{SS_\text{tot}}$$ where $SS_\text{res}=\sum_{i=1}^n (y_i-\hat{y_i})^2$ and $SS_\text{tot}=\sum_{i=1}^n (y_i - \overline{y})^2$.</p>
<p>Why is this used for assessing the fit of a least squares line? Why is the comparison based on looking at $SS_\te... | g49610 | [
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<p>How it is understandable for computer (or software) that a sampling method is Random? In fact, it is possible to data sampling by random method in N cases but one of the N cases been like as non-random! That means sampled data randomly is like non-randomly.
Now, in this case, how computer find out that selecting sa... | g809 | [
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<p>There is a set of daily measurements. Time and measured values are both discrete. I want to find out whether measured values depend on the day the measurement was taken, or whether measurements are completely random.
In other words, I want to find out if it is possible to predict measured values of a certain day or ... | g12556 | [
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<p>I have a project for which I had to do a 5-fold cross-validation. The dataset comprises of 5 days, so we take one day as our training set and apply on the remaining 4, rinse and repeat till we get full coverage. Pretty standard stuff. </p>
<p>Now, here's my question, once I finished the cross-validation, I am left ... | g57774 | [
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<p>I'm creating a classification model for detection of stress. I'm trying to select the best features from 56 total. </p>
<p>I have a matrix of <code>1937x56</code> with the non stress data, and a matrix of <code>1763x56</code> for stress data. </p>
<p><code>f_n -> non-stress matrix</code> and <code>f_s -> the... | g12557 | [
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<p>I am currently trying to simulate values of a $N$-dimensional random variable $X$ that has a multivariate normal distribution with mean vector $\mu = (\mu_1,...,\mu_N)^T$ and covariance matrix $S$.</p>
<p>I am hoping to use a procedure similar to the inverse CDF method, meaning that I want to first generate a $N$-d... | g12559 | [
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<p>I have two data sets with PDFs roughly like this:</p>
<p>$$
p(x) = \left\{
\begin{array}{lr}
.75 & x = 0\\
\text{Lomax}(x) & x > 0
\end{array}
\right.
$$</p>
<p>i.e. it's continuous, except there is a huge number of points at $x=0$. </p>
<p>I wish to tell if the values in o... | g57775 | [
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<p>While having chronically data of population growth (registered users of a site), I want to compute a function that approximates future growth, based on past data. Also, what we ll be the distribution of that function? What is the distribution of interarrivals between consecutive registrations.</p> | g57776 | [
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<p>For example if we have two options to use non-linear classifier like SVM with kernel or use linear classifier like linear SVM with data preprocessing like some non-linear dimensionality reduction which one is better?</p>
<p>In other words why we should use a complicated classifier if we can do some data preprocessi... | g57777 | [
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<p>I have time-series data, from which I would like to detect anomalies. I have Z-scored the time-series, and there is two points which clearly deviate from the baseline. Their Z-scores are 3 and 6, respectively. So, I can say they differ significantly from the baseline. Can I also say that the two anomalies themselves... | g57778 | [
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<p>Given a series of values,</p>
<pre><code>3.00,5.00,7.00,4.00,7.00,5.00,22.00,4.00,6.00,7.00,9.00,6.00,4.00
</code></pre>
<p>I need to 'rescale' the data so they have new values with a mean of 0 and a standard deviation of 1. Having followed a number of examples for the equation, I get the following,</p>
<pre><... | g57779 | [
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<p>I'd appreciate any insights or references to research regarding the following:</p>
<p>Suppose you have a discrete metric space with a probability distribution on it. also, suppose that I'm given a number $k$. My problem is finding the highest probability ball. </p>
<p>A <strong>ball</strong> is the set of all poin... | g57780 | [
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<p>The breaking strengths in pounds of five specimens of rope were 660, 460, 540, 580, and 550. </p>
<p>How can I estimate the point at which only 5 percent of such specimens would be expected to break?</p> | g1004 | [
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<p>My understanding is that if you (1) have a sufficiently large test dataset, and (2) your models have the same likelihood (noise assumption), then you should compare/select the model likelihood (or log-likelihood) on the test data, unadjusted by AIC/BIC/DIC/etc.</p>
<p>Is there any justification for adjusting your l... | g57781 | [
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<p>Is it possible to correct for violating the assumption of independence for nonparametric tests? </p>
<p>I have a categorical independent variable and a categorical and binary dependent variable, and each subject was exposed to multiple levels of treatment. I have done some preliminary analysis with binary logistic ... | g12563 | [
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<p>Given two basketball players.</p>
<p>John made 38/50 free throws.
Mike made 80/100 free throws.</p>
<p>What is probability that Mike is better at free throws than John?</p> | g57782 | [
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<p>In studying income inequality, it is very common to look at sample means for deciles or quintiles of the sample, and to assume that the sample means are good estimators of the true means. In this setting, the "deciles" and "quintiles" normally refer, not to the break points, but to the sets of observations divided b... | g12568 | [
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<p>In the discussion following a <a href="http://stats.stackexchange.com/q/18590/6633">recent question</a> about whether the standard deviation can exceed the mean, one question was raised briefly but never fully answered. So I am asking it here.</p>
<p>Consider a set of $n$ nonnegative numbers
$x_i$ where $0 \leq x... | g57783 | [
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<p>I'm a statistics novice and I need help with a natural language problem.</p>
<p>I'm writing a word-prediction algorithm for a mobile app. I'm using a unigram language model of word/count pairs where <em>count</em> is the number of times that <em>word</em> appears in a corpus. The algorithm is pre-loaded with a set ... | g12569 | [
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<p>What is the correct way of interpreting a changepoint graph? Here is what R gives for changepoint analysis of the mean of a data set:</p>
<pre><code>----------
Changepoint type : Change in mean
Method of analysis : AMOC
Assumed Distribution : Normal
Type of penalty : SIC with value, 4.770685
Maxi... | g57784 | [
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<p>I need a sort of review of all (or most of) available methods to create null distributions (as reference) to use to compare a result. For ex: if I want to validate a network I can create a set of 1000 random networks starting from the initial dataset, by shuffling 1000 times my data. Then I obtain a null distributio... | g41319 | [
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<p>I'm looking for a function to do that in R. I know how to write that function. Just don't want to reinvent something. </p> | g57785 | [
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<p>The negative binomial distribution has become a popular model for count data (specifically the expected number of sequencing reads within a given region of the genome from a given experiment) in bioinformatics. Explanations vary:</p>
<ul>
<li>Some explain it as something that works like the Poisson
distribution but... | g57786 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/31/what-is-the-meaning-of-p-values-and-t-values-in-statistical-tests">What is the meaning of p values and t values in statistical tests?</a> </p>
</blockquote>
<p>I currently start epidemiology class, I am... | g49294 | [
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<p>Is there a statistical program to calculate power for data generated by assigning a score (not necessarily linear ie score of 2 may not be equal to twice a score of 1)</p> | g57787 | [
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<p>I read from textbook that '<em>Autocovariance can fully charaterise the time series</em>' joint distribution', I do not fully understand the connection between covariance and joint distribution here. Please explain to me, someone? </p> | g57788 | [
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<p>For purely personal reasons, I recently tried to write a Ruby script that pulled information about various school rosters, counting the numbers of freshmen...seniors on the team and using that data to spit out some information about the teams relative youth based on the amount of eligibility left. As far as I am con... | g57789 | [
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<p>I just ran a vendor-supplied program that converts data from their proprietary binary format to what they call a "Matlab format". There are two resulting files from the conversion, a "filename.dat" and a "filename.m".</p>
<p>The "filename.m" file seems to have column heading information in it. The second "filename.... | g57790 | [
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<p>I have a point (x,y) that I need a linear regressor to pass through given a data set (X,Y). How do I implement this in R?</p> | g12578 | [
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<p>Why continue to teach and use hypothesis testing (with all its difficult concepts and which are among the most statistical sins) for problems where there is an interval estimator (confidence, bootstrap, credibility or whatever)? What is the best explanation (if any) to be given to students? only tradition? The views... | g49656 | [
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<p>I work with a lot of bar charts. In particular, these bar charts are of basecalls along segments on the human genome. Each point along the x-axis is one of the four nitrogenous bases(A,C,T,G) that compose DNA and the y-axis is essentially how many times a base was able to be "called" (or recognized by a sequencer m... | g34608 | [
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<p>I need to create random vectors of real numbers a_i satisfying the following constraints:</p>
<pre><code>abs(a_i) < c_i;
sum(a_i)< A; # sum of elements smaller than A
sum(b_i * a_i) < B; # weighted sum is smaller than B
aT*A*a < D # quadratic multiplication with A smaller than D
... | g57791 | [
0.02726748213171959,
0.008925328031182289,
0.00014367912081070244,
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0.07084627449512482,
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0.007989478297531605,
-0.015134983696043491,
0.0068009477108716965,
0.05041058361530304,
0.... |
<p>I ran an ad campaign on Facebook and I have impressions (ad-views), clicks, and sign-ups broken down by gender and age.</p>
<p>Certain demographics have a higher rate of clicks and sign-ups when compared to their respective percent of impressions. What is the best way to determine if these differences represent sig... | g12581 | [
-0.06003104895353317,
0.020393693819642067,
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0.0740857720375061,
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0.016736425459384918,
-0.005348880309611559,
0.024278365075588226,
-0.007185981143265963,
0.0590248703956604,
0.0... |
<p>I have a few questions regarding multiple imputation for nested data.
Context: I have repeated measures (4 times) from a survey and these are clustered in workplaces (205 workplaces). There are about 180 items on this survey.</p>
<p>q1. Is it possible to take both the repeated measures and the workplace clustering... | g57792 | [
0.039940014481544495,
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0.013979225419461727,
0.004583129659295082,
0.025082919746637344,
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0.005414056126028299,
-0.030322564765810966,
-0.013676726259291172,
0.006140750367194414,
... |
<p>I have a prospective study with no data about estimated results, that could be used to get required sample size. Data looks like this:</p>
<pre><code>caseID;groupID;value,result
1;1;12.3;0
2;1;15.6;1
3;2;11.3;0
4;2;13.4;1
...
</code></pre>
<p>Is it possible to determine how much observations should be made to com... | g12583 | [
-0.02215804159641266,
0.01612214185297489,
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0.03373481333255768,
-0.0021664644591510296,
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0.000057091911003226414,
0.042508307844400406,
0.029517417773604393,
0.018120544031262398,
0... |
<p>Is there a way to easily create factors based on quantiles of selected variables in a dataframe? Say, in a datatset D, I have variables V1 to V10, which are all numeric. I would like to create dummies for V7 to V10 based on their respective quantiles.</p> | g12584 | [
-0.0041745551861822605,
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0.0004984585102647543,
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0.031765278428792953,
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0.04056447744369507,
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0.06420595198869705,
... |
<p>I understand that Stepwise regression analysis has lots of limitations, including the assumption that the predictors are not highly correlated with each other. In fact, this limitation was the most important reason that I switched to Elastic Net, as I had 75 predictors in my model, some of which are highly correlate... | g57793 | [
-0.003974588587880135,
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0.030702972784638405,
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0.05583934113383293,
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0.03909304738044739,
0.027202647179365158,
0.005073528736829758,
-0.0608590692281723,
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-0.023501014336943626,
0.04184969887137413,
0.0... |
<p>Suppose I have 20 people matched in 10 pairs.</p>
<p>Suppose two doctors are assigned at random to diagnose one person in each pair, so in each pair each person is diagnosed by a different doctor. </p>
<p>Suppose that each doctor reports a vector of symptoms for each patient. That is, the response for patient $i... | g57794 | [
0.01265385840088129,
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0.00894036516547203,
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0.009833465330302715,
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0.006042536813765764,
-0.04470506310462952,
0.03218039125204086,
0.04444713518023491,
0.022455427795648575,
0.031071... |
<p><strong>Data</strong></p>
<p>I have a sample size of 50 in group A and 50 in group B where groups A and B are unmatched. Each sample in group A and group B has two frequencies associated with it, which I'll call $x$ and $y$. </p>
<p>A histogram of $x_{A}$ shows that it is clearly Gaussian and a Shapiro test confi... | g57795 | [
-0.0010165903950110078,
-0.03211640566587448,
-0.005922353360801935,
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-0.01138825248926878,
0.005854675080627203,
0.020889876410365105,
0.015111186541616917,
0.04881433770060539,
0.012732567265629768,
0.02345244213938713,
... |
<p>I have an Elastic Net model that is selecting a number of variables from X, for prediction of Y. The assumption for Elastic Net is that X is standardized (I'm using Z-Scores), and Y is centered around zero (I'm using Y-mean(Y)). So, I am wondering if my Elastic Net model will act differently if I use both standardiz... | g57796 | [
-0.0034628177527338266,
-0.03514554351568222,
0.02672586403787136,
-0.04039313644170761,
0.059143971651792526,
-0.044974539428949356,
0.030383218079805374,
0.04295425862073898,
0.0027463301084935665,
-0.026147974655032158,
0.0010710166534408927,
0.0020301593467593193,
0.034162260591983795,
... |
<p>I run 18 exploratory regressions and would like to know what the strict Bonferroni p-value would be.
Nine regressions are negative binomial regressions with 4 predictor variables, the other 9 are WLS regressions with 6 predictor variables. These associations are yet unexplored (my dependent variables are clinical q... | g57797 | [
0.029319046065211296,
0.04131728783249855,
-0.003925963770598173,
-0.02912159636616707,
-0.0331995002925396,
-0.059804338961839676,
0.03888649120926857,
0.00678222207352519,
-0.029448503628373146,
-0.07878357917070389,
-0.0035265402402728796,
-0.018258539959788322,
-0.004341622348874807,
0... |
<p>For independent random variables $ x_1,..,x_n$ and $y_1,...,y_n$ following normal distribution $N(0,1)$, I need a simple estimate formula for
$P(| \sum_1^n x_iy_i | \leq nt ) \leq e^{(?)}$ for $t>1$. Thanks. </p> | g57798 | [
-0.04675282537937164,
0.009867123328149319,
-0.0023998755495995283,
-0.04032914713025093,
-0.06400594860315323,
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0.03646070137619972,
-0.0522906631231308,
0.030231043696403503,
0.003516705706715584,
0.04... |
<p>I was looking for an intuition for the perceptron algorithm with offset rule, why the update rule is as follows:</p>
<p><em>cycle through all points until convergence</em></p>
<p>$\text{if }\, y^{(t)} \neq \theta^{T}x^{(t)} + \theta_0\,\{\\
\quad \theta^{(k+1)} = \theta^{k} + y^{(t)}x^{(t)}\\
\quad\theta^{(k+1... | g57799 | [
0.03890470787882805,
0.015277513302862644,
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0.026731079444289207,
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0.03706958889961243,
0.04846220463514328,
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0.04355704039335251,
0.014223203994333744,
0.07423369586467743,
-0.0027280314825475216,
0.06815... |
<p>I have a data set with around 14,000 observations. This is a sample data set not the population. </p>
<p>I have fitted a model (based on fuzzy logic) based on this data.</p>
<p>I have 27 actual values(from 14,000 observations) ans 27 values by model. Is it meaningful to use Kolmogorov-Smirnov test to justify my m... | g57800 | [
-0.0009472478413954377,
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0.0059052021242678165,
0.01279722061008215,
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0.009112593717873096,
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0.099103182554245,
-0.04005448520183563,
0.021635737270116806,
0.012532325461506844,
-0.020162681117653847,
0.04242420941591263,
0.03... |
<p>We evaluate Fisher information of a log likelihood function for a particular parameter in this process. How can we take expectation of the second derivative of log likelihood function with respect to a certain parameter? Which function is to be used while evaluating expectation?</p> | g57801 | [
0.008152344264090061,
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0.0055525703355669975,
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0.03953734412789345,
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0.020990317687392235,
0.041352905333042145,
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-0.036923542618751526,
-0.045702554285526276,
0.06028282642364502,
0.04661853611469269,
0... |
<p>From <a href="http://en.wikipedia.org/wiki/Box-Jenkins#Identify_p_and_q" rel="nofollow">Wikipedia</a></p>
<p>For AR(p), its p can be estimated from where its sample partial autocorrelation function (PACF) plot becomes zero.</p>
<p>For MA(q), its q can be estimated from where its sample autocorrelation function (AC... | g57802 | [
0.05030326917767525,
-0.07832073420286179,
0.002164366189390421,
-0.06920181959867477,
0.033311277627944946,
-0.050045471638441086,
0.06425271928310394,
0.012724828906357288,
-0.02213459089398384,
-0.047890398651361465,
-0.015379698947072029,
0.03894543647766113,
0.070538729429245,
-0.0025... |
<p>Consider a finite set $A$. Let the sample space be $A\times A$. We have an unknown probability distribution $f$ on this sample space. Now this probability distribution has a "blocky" property, which I am going to explain.</p>
<p>Let a block be a function (not necessarily probability distribution) over the sample sp... | g57803 | [
0.027008378878235817,
0.010704734362661839,
0.003070452716201544,
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0.025562793016433716,
0.02648937702178955,
0.005135281942784786,
0.05142202973365784,
0.000375957228243351,
0.022904157638549805,
0.03865533322095871,
0.024... |
<p>I divided my dataset into Test and Validation (50-50 split).</p>
<p>I ran glm function (link=binomial) on Test dataset and got the parameter estimates.</p>
<p>How do I score the Validation dataset based on these parameter estimates (beta) that I got from Test dataset. I know it has something to do with apply () bu... | g12587 | [
0.022768748924136162,
-0.03668397665023804,
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0.04115065932273865,
0.03618689253926277,
0.029665213078260422,
0.07349268347024918,
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-0.033286336809396744,
-0.045105211436748505,
0.03376290202140808,
0.0014243037439882755,
0.0... |
<p>Before data analysis, by $\frac{(X-mean)}{std}$, so the new variables have mean 0 and variance 1, and then compare different variables since then they are on the same measure scale, my question is, what is preserved about the data after standardizing then?</p>
<p>Thanks!</p> | g57804 | [
0.05911871790885925,
-0.038113128393888474,
-0.010284344665706158,
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0.020807353779673576,
0.012232828885316849,
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-0.043273597955703735,
-0.043369390070438385,
0.03764959052205086,
-0.027488460764288902,
... |
<p>I have a very beginner question about Logit coefficients. </p>
<p>I am trying to predict how often the home team with win a basketball game. I did a regression analysis much like the one on <a href="http://blog.yhathq.com/posts/logistic-regression-and-python.html" rel="nofollow">this page</a> and below are the va... | g57805 | [
-0.023873375728726387,
-0.04701613262295723,
0.025933505967259407,
-0.03130428493022919,
0.02351856231689453,
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0.04606463387608528,
0.012710309587419033,
-0.022272653877735138,
-0.027594251558184624,
-0.015597461722791195,
0.08822191506624222,
0.03954125568270683,
-0.045... |
<p>From All of Statistics by Wasserman:</p>
<blockquote>
<p><strong>Goodness-of-fit testing</strong> has some serious limitations. If reject $H_0$ then we
conclude we should not use the model. But if we do not reject $H_0$ we cannot conclude that the model is correct. We may have failed to reject simply
because ... | g57806 | [
0.07172167301177979,
0.010166817344725132,
0.025071168318390846,
0.05852079391479492,
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0.017195874825119972,
0.01801554299890995,
0.04866882041096687,
-0.03415081650018692,
-0.01982211321592331,
0.02313762716948986,
-0.0034551299177110195,
-0.007239747326821089,
0.02... |
<p>Suppose that you have jointly distributed $N$ (~100) random variables, $\{X_1,\ldots,X_N\}$, and this distribution is unknown to you. However you do know that their sum is zero by construction. Having $L$ (~3000) observations of $\max(X_1,\ldots,X_N)$ and $\min(X_1,\ldots,X_N)$ each, how can you make a statement abo... | g57807 | [
0.0002287412789883092,
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0.01692729815840721,
0.0060363151133060455,
0.007572045084089041,
-0.0037495444994419813,
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-0.03357001766562462,
-0.005096727516502142,
0.026416275650262833,
0.020992208272218704,
... |
<p>Say I have a series of forecasts and observations like this:</p>
<pre><code> EntityF EntityO
2004 120 125
2006 166 173
2008 150 167
2010 152 -
</code></pre>
<p>And assume that the (i) entity is the same and (ii) the forecasting methodology is constant.</p>
<p>I'd like to </p>... | g47918 | [
-0.001772759249433875,
-0.04002537950873375,
-0.014695697464048862,
-0.044541649520397186,
-0.003562838537618518,
-0.013555170968174934,
0.00022079508926253766,
0.04355846717953682,
-0.093245729804039,
-0.028032511472702026,
0.06798610836267471,
0.01748645305633545,
0.08879103511571884,
-0... |
<p>I have a function for performing one-way ANOVA in R:</p>
<pre><code>cond<-gl(4,5,20,label=c("a","b","c","d"))
aof<-function(x){
m<-data.frame(cond,x);
anova(aov(x~cond,m))
}
anova.results<-apply(x,1,aof)
</code></pre>
<p>I use it to perform ANOVA (testing four conditions, each with 5 samples) on seve... | g21255 | [
-0.022641243413090706,
0.00785923469811678,
0.0014734041178599,
-0.060257695615291595,
0.00832691602408886,
0.0031247902661561966,
0.03356640785932541,
0.028754400089383125,
-0.06073685735464096,
0.011234850622713566,
-0.02141651138663292,
0.019332904368638992,
0.01691795513033867,
0.06248... |
<p>I'm running a binom.test on the data set UCBAdmissions (comes with R) and am stuck on an error message.</p>
<p><strong>About the data:</strong></p>
<pre><code>> str(UCBAdmissions)
table [1:2, 1:2, 1:6] 512 313 89 19 353 207 17 8 120 205 ...
- attr(*, "dimnames")=List of 3
..$ Admit : chr [1:2] "Admitted" "Rejec... | g13200 | [
0.02235744334757328,
0.00007512862066505477,
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0.037429992109537125,
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0.04848899319767952,
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-0.05964253097772598,
-0.0557662695646286,
0.06866591423749924,
0.04046420753002167,
-0.02... |
<p>I want to train a linear regression model to predict a non-linear variable. This how the two independent variables correlated against the response (points are jittered):</p>
<p><img src="http://i.stack.imgur.com/U1Ksu.jpg" alt="enter image description here"></p>
<p><img src="http://i.stack.imgur.com/Hf95A.jpg" alt... | g57808 | [
-0.029658816754817963,
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0.006684481166303158,
0.05766075477004051,
-0.05508049577474594,
-0.0020154390949755907,
0.02572871744632721,
0.02970561571419239,
0.014542307704687119,... |
<p>I was looking at the following statement and felt I needed some help in sorting it out:</p>
<p>A random sample of size n from a population $f(x)$ is a collection of n independent random variables $X_1,...,X_n$, each having the distribution $f(x)$.</p>
<p>let us apply the above statement to all freshmen at a certai... | g38102 | [
0.000012467816304706503,
0.029167935252189636,
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0.003173807170242071,
0.024633098393678665,
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-0.03029835969209671,
-0.02830067090690136,
0.015777140855789185,
0.009724508970975876,... |
<p>I am interested in using a spatial research design. Imagine a line, like a time zone line. For example, in the United States, the line that makes between Eastern Standard Time and Central Standard Time runs North to South through the U.S. (and other places), more or less. </p>
<p>Suppose the United States impleme... | g57809 | [
0.0544840469956398,
0.046148765832185745,
-0.01872524805366993,
-0.0428311787545681,
0.014607989229261875,
0.004311348311603069,
-0.011460145004093647,
0.03989097476005554,
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-0.02809840440750122,
0.017607221379876137,
-0.021905815228819847,
0.05154518410563469,
0.0247... |
<p>Now I have two data set which is generated by two listing flow of a e-commerce site. And these data set has different conversion rate, my task is to analysis the two data set and found out which factors lead the different conversion rate. BTW, most of the data is categorical data. Could you help point me some tutori... | g57810 | [
-0.009407373145222664,
0.03703298419713974,
-0.0028790063224732876,
-0.04015609994530678,
0.05463028699159622,
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0.04485826566815376,
0.04166410118341446,
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0.0007807600195519626,
0.026423834264278412,
0.058563608676195145,
0.08857192099094391,
0.0... |
<p>Is saying random numbers are independent equivalent to saying random numbers are auto-correlated in simulation. I am using Auto-correlation method in simulation.</p> | g57811 | [
0.023441681638360023,
0.020571045577526093,
-0.003567997133359313,
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0.03539203107357025,
0.0168935414403677,
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0.01779082603752613,
-0.02448711358010769,
-0.02570827677845955,
0.03985714912414551,
0.008252983912825584,
0.002... |
<p>Say $X$ is a discrete random variable with cardinality $|X|$ and $Y$ is a discrete random variable with cardinality $|Y|$. </p>
<p>Does it make sense to talk about the KL divergences $D_{KL}(X||Y)$ or $D_{KL}(Y||X)$ of these 2 probability distributions if $|X| \neq |Y|$ ? If so, how does one compute it ?</p> | g57812 | [
0.032048679888248444,
0.023791257292032242,
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0.012585009448230267,
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0.05803516134619713,
-... |
<p>This is much the same question that <a href="http://stats.stackexchange.com/questions/38102/paired-versus-unpaired-t-test">I asked a few weeks ago</a>, but I hope to explain myself more clearly this time.</p>
<p>I start with 40 mice. I use my own scheme, based on my own ideas for how to make the two mice in a pair ... | g57813 | [
0.045305050909519196,
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<ol>
<li><p>Assume that I have decomposed a data set using Symlet Wavelet with six levels. How can I estimate the approximate frequency interval of each level?
That would be great if you consider your answer in the Mathematica environment.</p></li>
<li><p>If the above dataset describes turbulent velocity field, how I c... | g57814 | [
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<h2>Question</h2>
<p>I have a vector of data, and I want to test if it came from a normal distribution with mean zero and unknown variance. Do you know if there is matlab function or simple script for this? If you don't know anything matlab specific, then a name and reference for the specific test is fine and I will j... | g57815 | [
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<p>My multiple regression analysis model has a statistically significant F value however all beta values are statistically non-significant. </p>
<p>All the regression assumptions are met. No multicollinearity was found. Correlations among all predictors are all less than 0.60. </p>
<p>What else might be the cause of ... | g49368 | [
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<p>I have some physiological measurements which consist of 4 events measured in a "during task" condition and preceded and followed by a rest period.</p>
<p>I want to test that the data points immediately preceding the 4 events do not differ from the rest baseline, calculated as the average of the values in the start ... | g57816 | [
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<p>In epidemiology, we often deal with lots of factors associated with disease. This multitude of factors makes plots of effect sizes (often hazard ratios) of individual factors confusing. Accepting some oversimplification, factors can for the most part be reasonably assigned to some group like nutritional, lifestyle, ... | g57817 | [
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<p>If we take the logarithm of the Cobb-Douglas production function, we get:</p>
<p>ln(Y)=A+$\beta_1$ln(L)+$\beta_2$ln(K)+$\epsilon$ln(e)</p>
<p>I understand that in the production function, the coefficients $\beta_1$ and $\beta_2$ are output elasticities of labor and capital. What would be the interpretation of thes... | g40537 | [
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<p>I can use a GridSearchCV on a pipeline and specify scoring to either be <code>'MSE'</code> or <code>'R2'</code>. I can then access <code>gridsearchcv._best_score</code> to recover the one I specified. How do I also get the other score for the solution found by GridSearchCV? </p>
<p>If I run GridSearchCV again with ... | g2928 | [
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<p>Do you know some good references (papers or books) for the theoretical inference in Deming's regression model ?</p>
<p><strong>EDIT:</strong> I was a little disconcerted about a point in Ripley and Thompson's paper <a href="http://pubs.rsc.org/en/Content/ArticleLanding/1987/AN/an9871200377" rel="nofollow">Regressio... | g57818 | [
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<p>As some of you may now, various statistical tests are used in the task of finding collocations in given text(either a single document or corpus of texts). Chi-square, t-test, likelihood ratio(with binomial distribution assumed). These tests are used to check if two words occur together significantly more often that ... | g57819 | [
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<p>The basic idea i'm trying is to model the data with factor analysis, <strong>assuming a latent variable structure</strong> that underlies the observations. Labels for "real" anomalies are available and used for validation. Another important note is that the data does not have a "very" Gaussian nature. </p>
<p>Then,... | g12606 | [
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<p><em>(Remark: this is a "scholastic" question - I'm reviewing my implementation of factor analysis procedures; I'm not looking for good approximations for an actual survey/actual data or the like.)</em> </p>
<p>There are different methods of estimating individual variances for the items in a covariance matrix $... | g37554 | [
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<p>before my actual ANCOVA I would like to test whether there is a significant interaction between the IV and the CV as this is one assumption for ANCOVA. I found 3 different ways in R to perform an ANCOVA. However, the result for one solution differs from the other two and I do not understand why. Here is my working c... | g57820 | [
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<p>I'm trying to evaluate the linear correlation between to continuous variables (% value calculated from EEG datas and the area of an anatomical region of the brain). I have a sample of 18 right now.
From what I understand, I need to make sure that the x and y variables vary together in a joint distribution that is no... | g57821 | [
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<p>I have seen several references, but am looking for something easy to follow that illustrates Random Forests in regression and feature importance applications.</p>
<p>I want to make sure that I explain this at the 101 level. Something like <a href="http://edchedch.wordpress.com/tag/ensemble-methods/" rel="nofollow">... | g57822 | [
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<p>I am looking at the absolute difference in values between pairs of numbers. I am then comparing these absolute values between two groups (e.g. Males and Females). Since these are absolute values I am not sure whether it is appropriate to use parametric statistics (e.g. Independent t-test) or whether it is better t... | g57823 | [
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<p>I have just read one of the answer from a member as follow:</p>
<p>"One of the biggest reasons for the confusion between the two has to do with the fact that one of the factor extraction methods in Factor Analysis is called "method of principal components". However, it's one thing to use PCA and another thing to us... | g12607 | [
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<p>I am using the MIXED command in SPSS to run a multilevel model and was wondering what the difference is when using a dummy coded factor either as factor (via the BY command) or as a covariate (via the WITH) command.
A similar question was already posted here: <a href="http://stats.stackexchange.com/questions/23314/b... | g57824 | [
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<p>I am writing a routine for logistic regression with lasso in <code>matlab</code>. So the problem is to minimize the negative log-likelihood function with the penalty term</p>
<p>$$\sum \left(\log(1 + e^{X_i' \beta}) - y_i X_i' \beta\right) + \lambda \sum |\beta_i|$$</p>
<p>where $\beta$ is the model parameter, $X_... | g57825 | [
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<p>Given a rainfall forecast of <code>d days</code> ahead and historic data collected over <code>y years</code>, what's a simple (but correct) way to associate the rainfall probability for each forecast day? </p>
<p>I know this is a complex problem, but my purpose is to quantify the probability of a given rainfall vol... | g12608 | [
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<p>Say you gave an IQ test to a random sample of $n$ people, but instead of having the actual test results, you have only the normalized data for this sample (mean=0, $\sigma$=1).</p>
<p>What is the probability that person $A$ is in the top 5% of the total population (1.64 standard deviations above mean), given that t... | g57826 | [
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<p>I'm analyzing a vote result in my country and I'm using a logistic model for this task (glm). The population was asked to vote yes or no, which resulted in an approval-value from 0% to 100% for each municipality. I would like to weight this result based on the people who have voted, since in small municipalities onl... | g57827 | [
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<p>I am predicting a time series' future evolution and am evaluating the path uncertainty using bootstrapping.</p>
<p>Is there a good way to visualise the uncertainty that goes beyond simply plotting a pair of confidence bands, e.g. 90% lines? I thought of something that gives a better feeling for the distribution at ... | g12610 | [
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<p>Suppose I have the following model </p>
<p>$$y_i=f(x_i,\theta)+\varepsilon_i$$</p>
<p>where $y_i\in \mathbb{R}^K$ , $x_i$ is a vector of explanatory variables, $\theta$ is the parameters of non-linear function $f$ and $\varepsilon_i\sim N(0,\Sigma)$, where $\Sigma$ naturally is $K\times K$ matrix. </p>
<p>The go... | g41377 | [
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<p>I am modelling two dimensional ovals on a two dimensional plane. Each oval is defined by five parameters, namely <code>x, y, s1, s2, t</code> where <code>x</code> and <code>y</code> are its position on the plane, <code>s1</code> and <code>s2</code> are length of its long and short axis respectively and <code>t</code... | g57828 | [
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<p>I can't seem to find a general method for deriving standard errors anywhere. I've looked on google, this website and even in text books but all I can find is the formula for standard errors for the mean, variance, proportion, risk ratio, etc... and not how these formulas were arrived at. </p>
<p>If any body could e... | g57829 | [
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<p>I have a situation where I have an observed statistic computed from data, and then I have approximated the null distribution by some sort of resampling. I have used this to calculate p-values for a one-sided hypothesis test. </p>
<p>Now, if I want to do a comparison between two statistics (are they significantly di... | g15535 | [
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<p>I've been searching for a few days on a number of sites but I can't seem to find a good answer for this. I'm developing a collision detection program using Unscented Kalman Filter and predicting possible positions of different objects.</p>
<p>These objects have a certain area but my predictions are of course only p... | g57830 | [
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<p>I observe $\vec y$ and know $\vec x$. I assume that $\vec y$ mostly consists of $\vec x$, with some added residual $\vec r$.</p>
<p>This gives me the problem $\vec y = a\vec x + \vec r$, where $a \in [0, 1]$. Furthermore, I assume that we should maximize $a$. Otherwise, $a = 0, \vec r = \vec y$ would be a trivial s... | g57831 | [
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<p>I'm trying to understand the definition of a sufficient statistic for continuous random variables given in Introduction to Mathematical Statistics by Hogg and Craig (7th edition).
Let $X_1,X_2,...,X_n$ be a random sample with joint pdf
$f(x_1,x_2,...,x_n;\theta)$, $\theta \in \Omega$, and $T(X_1,...,X_n)$ be a stat... | g12613 | [
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<p>Does this mean you can't compute the median?</p> | g41384 | [
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<p>I am trying to build GAM model to see the effect of several environmental variables on the total abundance of one species. I have collected samples from three sites with three replicates from each site. How is the best for me to see the effect of each variable on the model after removing the variation cause by the t... | g57832 | [
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0.03092885948717594,
0.01202397421002388,
0.02468709461390972,
0.035483554005622864,
0.02572738192975521,
0.047632329165935516,
-0.0133... |
<p>So I've been trying to analyze 3 repeats for some data (essentially, a single independent variable measured at three different times), which would look like something like this:</p>
<p>Test 1
[Value]
Test 2
[Value]
Test 3
[Value]</p>
<p>Now, I want to see if these values are different from one another, but I don'... | g57833 | [
-0.01581110619008541,
-0.004669730551540852,
0.008076835423707962,
-0.01199828740209341,
0.0010417681187391281,
-0.02159813418984413,
-0.013347674161195755,
-0.013550764881074429,
-0.03788822144269943,
0.017027001827955246,
-0.039832331240177155,
0.03691929206252098,
-0.0415496751666069,
0... |
<p>I am using like 10 predictors in my decision tree, but the rpart function uses only like 8 of them. does it mean that rest 2 are not needed or they become redundant? like i have age and child coded based on age as 1/0. but the tree uses only age and not child.</p> | g57834 | [
-0.006182840093970299,
-0.03929834067821503,
0.014560862444341183,
0.0030442429706454277,
0.02953372709453106,
-0.003724008798599243,
0.02156328223645687,
0.027736784890294075,
-0.02779923565685749,
-0.038166675716638565,
-0.04726160317659378,
-0.01905161514878273,
-0.005549973342567682,
0... |
<p>Suppose I want to generate a nonnegative $n \times n$ matrix $\mathbf A$ for an odd $n$ (say, $n=5$ for a good enough example), such that</p>
<ul>
<li>the individual elements are drawn from a uniform distribution</li>
</ul>
<p>but with the equality constraints</p>
<ul>
<li><p>the sum of all the elements in the ro... | g12617 | [
-0.001392363104969263,
0.0019093191949650645,
0.00601007416844368,
-0.09358999133110046,
-0.017448797821998596,
-0.04993240907788277,
-0.049858905375003815,
0.023023024201393127,
0.006804262287914753,
-0.032296109944581985,
0.014406450092792511,
-0.016680989414453506,
0.01207576971501112,
... |
<p>Suppose I do the following: </p>
<pre><code> proc phreg data = new;
model time*censor(0) = x y;
run;
</code></pre>
<p>Also suppose $x$ is a binary variable and $y$ is a continuous variable. How would I plot the survival function for $x = 1$ and $y = 100$ (for example) in SAS?</p> | g57835 | [
0.000009922448043653276,
-0.07244154065847397,
0.004519491922110319,
0.01922762580215931,
0.005447203293442726,
-0.021920591592788696,
0.002011277014389634,
-0.024929415434598923,
-0.07842076569795609,
-0.01467188075184822,
0.004359621088951826,
0.015513090416789055,
0.04574417695403099,
0... |
<p>I'm re-analyzing a colleague's data. The data and R code <a href="https://gist.github.com/1409791" rel="nofollow">are here</a>.</p>
<p>It's a 2x2x2x2x3 completely within-Ss design. One of the predictor variables, <code>cue</code>, is a two-level variable that when collapsed to a difference score reflects a theory-p... | g12620 | [
0.0011084730504080653,
-0.05970163643360138,
-0.004281783476471901,
-0.029440445825457573,
-0.014308459125459194,
0.05520689859986305,
0.059666525572538376,
0.024761172011494637,
-0.013796619139611721,
-0.03758269175887108,
0.012582442723214626,
-0.038111019879579544,
0.08977758884429932,
... |
<p>Logistic regression fits a model that predicts a binary variable whilst performing a logit transformation of the linear combination (LC) of predictors: 1/1 + exp(-LC).</p>
<p>I have a working machine learning algorithm which does the same but fits a non linear combination of predictors by maximising the log likelih... | g37911 | [
0.023316765204072,
-0.09306653589010239,
-0.003965336363762617,
-0.019290795549750328,
0.019286522641777992,
-0.0008044471614994109,
0.019638733938336372,
0.07501042634248734,
-0.053265418857336044,
-0.00697200745344162,
0.015017924830317497,
-0.004673924297094345,
0.08103372901678085,
0.0... |
<p>I am trying to construct a mixed effects model and to include in it a measure of the (genetic) distance between observations, so that closer observation from different main effect levels will <strong>outweigh</strong> distant observations from different main effect levels.<br>
I have constructed a similarity matrix ... | g57836 | [
-0.013261961750686169,
-0.032178860157728195,
-0.010506991297006607,
-0.0755922943353653,
0.028655286878347397,
0.022022562101483345,
0.02394680492579937,
0.02812417969107628,
-0.037200797349214554,
-0.07268372178077698,
0.0003533709386829287,
0.03224148601293564,
0.05496933311223984,
0.00... |
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