question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>In linear discriminant analysis, how is the linear discriminant function determined? Assuming equal variance-covariance matrices, is the linear discriminant function determined from the training data? </p> | 29,322 |
<p>Suppose I have the following time-series linear model where $\beta$ is misspecified:</p>
<p>$Y(t+1) = \alpha + \beta X(t) + \sum_{i=1}^{10000}\gamma_i Z_i(T) + \varepsilon$</p>
<p>where all parameters are in $\mathbb{R}$ and all predictors are normally distributed and play nicely with respect to Gauss Markov.</p>
... | 69,050 |
<p>I have two datasets:</p>
<ol>
<li><p>I have an exam score (pretend is the GRE) for all students that took the exam from 2000-2005, although I do not have student's private information (names, id,etc) I several variables along with the score such as socioeconomic status, race, parent's education, type of school, etc... | 39,449 |
<p>I am testing the significance of observed data sampled ($n\approx50$) using a multinomial distribution with known probabilities (with ~20 categories). Given the probability of observing the sample $P_{sam}$, I would like to compute the p-value, which is defined as the sum of all probabilities lower than this observe... | 69,051 |
<p>The number of faults in one metre of a thread is Poisson distributed.It is claimed that the average number of faults is 0.02 per metre.A random sample of 100 one metre lengths of the thread reveals a total of 6 faults.Does this information support the claim?</p>
<p>What I want to know whether my H0 should be, H0:<s... | 25,192 |
<p>What are some good visualization libraries for online use? Are they easy to use and is there good documentation?</p>
<p>Thanks.</p> | 39,450 |
<p>I have 2 ASR (Automatic Speech Recognition) models, providing me with text transcriptions for my testdata. The error measure I use is Word Error Rate.</p>
<p>What methods do I have to test for statistical significance of my new results?</p>
<p><strong>An example:</strong></p>
<p>I have an experiment with 10 speak... | 69,052 |
<p>Suppose I have a large set of multivariate data with at least three variables. How can I find the outliers? Pairwise scatterplots won't work as it is possible for an outlier to exist in 3 dimensions that is not an outlier in any of the 2 dimensional subspaces.</p>
<p>I am not thinking of a regression problem, but o... | 49,448 |
<p>My experiment entails comparing a mock-infected group with a virus-infected group across 4 different time points (3,5,8,10 weeks) looking at the proportion of immune cells. </p>
<p>I have already compared the mock and virus infected groups at each time point by using an unpaired t-test.</p>
<p>How can I compare th... | 69,053 |
<p>In my logistic regression analysis, my dichotomous predictor variable 'A' gave a strange p value of 1.00 under Wald's test. The analysis was done with 2 continuous covariates, a continuous predictor variable and an interaction variable consisting of the continuous predictor and the dichotomous predictor. The DV is a... | 69,054 |
<p>I have something that seems to me an incongruence in ANOVA post hoc tests, and I would like to have an explanation. Basically I performed an ANOVA at the global level on my data and then I performed a post hoc test using both LSD and Tukey's HSD procedure.
First I did the ANOVA on the whole data set and post hoc tes... | 69,055 |
<p>Suppose that we have $X_1,...,X_n$ iid observations from a Geometric($p$) distribution. </p>
<p>I found that the MLE of p is $\hat{p} = \frac{n}{n+\sum{X_i}}$.</p>
<p>I am trying to find the MLE of $\theta = \frac{p}{1-p}, \hat{\theta}$ and the Fisher Information of a single observation $I_1(\theta)$.</p>
<p>Now,... | 29,328 |
<p>I have a non-negativity constrained LASSO problem like this: </p>
<blockquote>
<p>min: $||Cx-b||_2^2 + \lambda||x||_1$</p>
<p>subject to: $x\geq0$</p>
</blockquote>
<p>where C is a matrix, and x and b are column vectors. Now I want to use cross-validation to determine the regularization parameter $\lambda$.... | 29,329 |
<p>I work in the loss forecasting area and would like to know a little bit more about the theory and implementation of age-period-cohort models. Several papers pop up in google search but I need a more comprehensive material relating to identification/estimation. Thank you.</p> | 29,330 |
<p>I want to estimate $n+m$ parameters with the equation:
$$\hat\theta=\left[\frac{1}{N}\sum_{t=1}^N \varphi(t)\varphi^T(t)\right]^{-1}\left[\frac{1}{N}\sum_{t=1}^N\varphi(t)y(t)\right]$$
where $\varphi$ is a vector of regressors and $\theta$ the vector of parameters.
Then my book derive an expression for the estimatio... | 69,056 |
<p>This is a follow-up question from one I asked over at MathOverflow: <a href="http://mathoverflow.net/questions/158806/is-there-a-simple-closed-form-solution-for-the-joint-density-distribution-of-an">http://mathoverflow.net/questions/158806/is-there-a-simple-closed-form-solution-for-the-joint-density-distribution-of-... | 69,057 |
<p>Why would the results of the ANOVA be non-significant, while a pair-wise comparison using Tukey's WSD is significant? Is their a general pattern in the means of the data that would typically produce this result?</p> | 69,058 |
<p>Assume $X$, $Y$ are independent zero mean random variables. Define $Z_1=X+Y$ and $Z_2=X-Y$. Then, their mean values are the same.</p>
<p>How does one check that $Z_1$ and $Z_2$ are not the same random variables?
And how to describe their variances?</p> | 29,333 |
<p>I have plotted my predictors versus my response variable in order to be able to fit a good Poisson model to my data. However i am getting those scatter plots for nearly all predictors which make me rather worried since including these predictors is making my residual deviance a value of 575 on 571 df(high enough) T... | 49,597 |
<p>I realize this may be a very general number, however, I'm very new to data visualization. </p>
<p>Any links to appropriate material is greatly appreciated.</p>
<p>Actual question/background: My team and I, for a school project, are assigned to write a program to visualize the AES encryption algorithm. Problem co... | 29,334 |
<p>I know <strong>k-means</strong> is usually optimized using <strong>Expectation Maximization</strong>. However we could optimize its loss function the same way we optimize any other! </p>
<p>I found some papers that actually use stochastic <strong>gradient descent</strong> for large scale k-means, but I couldn't get... | 29,335 |
<p>I am using the R package boot and the cv.glm function. The output 'delta' gives me the un-adjusted and adjusted prediction error. Here is an example on the top of page 10: <a href="http://www.unt.edu/rss/class/Jon/Benchmarks/CrossValidation1_JDS_May2011.pdf" rel="nofollow">http://www.unt.edu/rss/class/Jon/Benchmarks... | 25,240 |
<p>Suppose that we are given 1000 doses between 0 and 10 and various ordinal values (1 = normal, 2 = critical condition, 3 = death). So typical data points would of the form: $(5,1), (6,1), (10,3)$ etc.</p>
<p>What is the purpose of using regression to obtain LD50? Couldn't we just look at the data and see at what do... | 69,059 |
<p>I'm looking for linear regression algorithm that is most suitable for a data whose independent variable (x) has a constant measurement error and the dependent variable (y) has signal dependent error.</p>
<p><img src="http://i.stack.imgur.com/3luKI.png" alt="enter image description here"></p>
<p>The above image ill... | 69,060 |
<p>I am trying to use Cronbach's alpha in order to see if some variables are measuring the "same", but I have some doubts about the correct use:</p>
<ol>
<li><p>Can I compute alpha for numerical, ordinal or dichotomous variables? If it is correct to do that, then may I mix dichotomous, ordinal and numerical variables?... | 69,061 |
<p>I have two question about profile log-likelihood. One is of theoretical nature and one is about a plot in R. I illustrate the two questions in a application of profile-likelihood in EVT. I use the package <code>evd</code>.</p>
<pre><code>> data(lisbon)
> fgev(lisbon)
Call: fgev(x = lisbon)
Deviance: 241.245... | 32,891 |
<p>Happy New Year '14 everyone. I'm seeking a formal solution to a simple problem. I'm working with a database of a toxic element in different regions. I want to prioritize regions where immediate action should be taken based on my soil data (mean concentration of the toxic element in a region and the fraction of soil ... | 69,062 |
<p>I have a set of images of same color cars which I have users rate on a scale from 1-5 (integers only) based on how attractive they think the car design is. For each image I have a set of parameters about the cars in question, mostly various ratios of dimensions (say height at middle, width at trunk, curviness of hoo... | 69,063 |
<p>What are the different measures of effect size used for chi-squared tests / binomial data? I'm already at least somewhat familiar with the phi coefficient and odds ratio. I've heard of Cramer's V and relative risk as well. However, I'm still not sure how to decide which effect sizes to report in different circumstan... | 69,064 |
<p>I'm wondering which quality measures are available for non-binary classifiers. I've read this article</p>
<p><a href="https://en.wikipedia.org/wiki/Receiver_operating_characteristic" rel="nofollow">https://en.wikipedia.org/wiki/Receiver_operating_characteristic</a></p>
<p>I understand, that the idea of Confusion m... | 69,065 |
<p>I have computed a correlation matrix from certain data set of dimension 6</p>
<p>The correlation matrix is:</p>
<pre><code> 1.000000000000000 -0.142753907555000 -0.192138186332000 -0.523853268770000 0.124444699394000 0.002606132276000
-0.142753907555000 1.000000000000000 0.035741740609000 0.052631092693000 0... | 987 |
<p>Could you explain the need of temporal abstraction in churn analysis intuitively with a simple example? I tried Google but there are not any clear answers , especially for churn analysis. </p> | 69,066 |
<p>I'm working on understanding the derivation of the optimal time constant for filters based on minimizing mean squared error. Unfortunately the text made a big jump between steps and lost me.</p>
<p>Here's part of the derivation:</p>
<p>$$
\theta_g = \theta +\sigma_g^2 +B_g
$$
Where $\theta$ is the actual value, an... | 29,345 |
<p>I have a formula like that:</p>
<p>${ \sum_{s} P(S=s|C=c)} $</p>
<p>I don't know what does it mean?</p>
<p><strong>i.e.</strong> P(S|C)+P(~S|C)?</p> | 39,471 |
<h2>Introduction</h2>
<p>For some time now I have been struggling to understand how theoretical results can be applied in practice. Fortunately in most cases the link between theory and practice is not hard to find, for instance:</p>
<ul>
<li>You can directly use a theoretical result for your calculations.</li>
<li>Y... | 69,067 |
<p>I have a time series of correlation matrics (generated from a multivariate time series over time). Here I am wondering what is the best way to graphically represent the times series of corr matrices? Should I just extract individual pair and plot time series individually? What is the best practice?</p>
<p>Thanks fo... | 29,347 |
<h2>Premise:</h2>
<p>For a product and a user, the system has to recommend him/her other non-users related with him/her that are most likely to be interested in that same product.</p>
<h2>Available data includes:</h2>
<ol>
<li><p><strong>Non-users:</strong> </p>
<ul>
<li>Basic demographics (<em>e.g.</em> age, gend... | 69,068 |
<p>Lets say you are given a set of $n$ points and for each one, you want to get a measure of dispersion of its closest $d$ points. So a point far away from others will have a large measure of dispersion while points in a cluster have a low measure of dispersion. Anyone know which statistic would be useful for this? </p... | 69,069 |
<p>I was reading about HMM in C.M. Bishop's book <a href="http://research.microsoft.com/en-us/um/people/cmbishop/prml/" rel="nofollow">Pattern Recognition and Machine Learning</a>. I was going through the forward and backward algorithm using $\alpha$ & $\beta$</p>
<p>For forward messaging passing</p>
<p>$\alpha(z... | 69,070 |
<p>I have this confusion related to the benefits of Gaussian processes. I mean comparing it to simple linear regression, where we have defined that the linear function models the data.</p>
<p>However, in Gaussian processes we define the distribution of the functions means we don't specifically define that the function... | 37,951 |
<p>I take a SRS sample of size n from a population of x values ranging from 1 to N. Each selected unit also has a probability p of success or q = 1-p of failure (i.e. the probability of success/failure is independent of the value of x).</p>
<p>What is the expected value of the minimum x value for which success occurs?... | 29,350 |
<p>I'm still trying to expand my statistics and forecasting technique knowledge.</p>
<p>Right now I'm forecasting seasonal contact patterns, so the simplest model I can understand with seasonality is a Holt-Winters/ Triple exponential smoothing model.</p>
<p>For many of our decisions, we not only need predictions for... | 69,071 |
<p>I have a matrix X where the rows denote the cases and the columns the variables. I use a standard row-metric preserving biplot in order to represent the cases in a subspace. If I wanted to add a supplementary point (i.e. a row) I can simply project the point it into that space.</p>
<p>But, how can I optimally fit a... | 29,352 |
<p>I am struggling to understand full column rank vs. full row rank to estimate parameters of multivariate regression case. When do we use row rank, and when do we use column rank?</p> | 69,072 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/32419/difference-between-generalized-linear-models-generalized-linear-mixed-models-i">Difference between generalized linear models & generalized linear mixed models in SPSS</a><br>
<a href="http://stats.... | 49,819 |
<p>I have two sets of data: the bacteria count on people's hands (n=1e4) without washing <code>x</code>. They then washed their hands and the count was made again <code>xwash</code>. What is the best way to estimate the reduction between these groups? </p>
<p>Is there a formalised/sophisticated comparison test or a... | 29,354 |
<p>I am trying to beat the performance of an SVM classifier in a text classification task.
Input is a bag of words model of sentences with 1 representing presence and 0 representing absence. Output is 1 of 4 possible labels. Are DBNs directly applicable to this class of problems? I get an error of 0.38 on the test set... | 69,073 |
<p>I am trying to model some data that follows a sigmoid curve relationship. In my field of work (psychophysics), a Weibull function is usually used to model such relationships, rather than probit.</p>
<p>I am trying to create a model using R. My model will have a 'shape' and 'scale' value. In order to generate this m... | 69,074 |
<p>Is there a way to use correlation to interpolate missing data?</p>
<p>I know the wind speed in 6 locations every hour. This shows the correlation between the separate locations. <a href="https://dl.dropboxusercontent.com/u/100778374/Wind%20Data/5MinuteData_CWP_Capacity.csv" rel="nofollow">Hourly Data</a></p>
<p>I ... | 29,356 |
<p>Following my initial question (stats.stackexchange.com/questions/108874/continuous-time-markov-chains-simple-explanation) and some further reading on CTMC (<a href="http://www.columbia.edu/~ks20/stochastic-I/stochastic-I-CTMC.pdf" rel="nofollow">[1]</a>, and <a href="http://www.mast.queensu.ca/~stat455/lecturenotes/... | 33,180 |
<p>I have a very highly sampled time series that I would like to fit an autoregressive model (AM) to (~3 million samples). From knowing what they represent, I have believe there should be unique information out to ~1k sample points in the past. Thus I'm considering modifying a more standard AM.</p>
<p>This is what I'... | 29,358 |
<p>I am investigating differences in two groups of forecast errors (absolute values / unsigned) that both have a strongly right-skewed distributions. Both groups of errors have the same number of observations (about 4000). As I like to test if the interquartile range and the fraction of errors that are <0.4 differ s... | 69,075 |
<p>I understand examples where two nodes can be dependent but conditionally independent given their common cause. For instance the common cause is high temperature, and the children nodes are high icecream sales and more number of sharks. The children are correlated through the high temperature, but independent given t... | 69,076 |
<p>I take the bus to work and I am trying to make a prediction interval for the journey time to work so that I can leave the house and be 99% sure I will get to work on time.
The journey has 2 parts.</p>
<ol>
<li><p>Waiting for the bus, the bus is meant to come every 10 minutes but because of traffic this varies a bit... | 69,077 |
<p>Winsorizing data means to <strong>replace</strong> the extreme values of a data set with a certain percentile value from each end, while Trimming or Truncating involves <strong>removing</strong> those extreme values. </p>
<p>I always see both methods discussed as a viable option to lessen the effect of outliers whe... | 69,078 |
<p>I have a big group of 1052 people. Out of 18 people with trait A 11 people also have trait B.
Out of the whole group of 1052 people 569 have trait B.</p>
<p>How do I determine in R whether the trait B is significantly different distributed in people with trait A compared to the overall population?</p> | 69,079 |
<p>In many applications such as estimation theory, when we need to estimate a parameter then we usually consider in presence of white gaussian noise of zero mean and some standard deviation. During Maximum likelihood estimation, we also use this assumption. So, my question is -</p>
<ol>
<li><p>Do we consider noise to ... | 36,036 |
<p>I have the following Markov Switching Model.</p>
<p>Transition Matrix:</p>
<p>$$
\left[\begin{matrix}
0.85387 & 0.91973\\0.14613 & 0.080265
\end{matrix}\right]
$$</p>
<p>With </p>
<p>Regime 1:</p>
<p>Intercept: 0.00839
AR1: 0.26694
MA1: -0.26571
Var: 0.00244</p>
<p>Regime 2:</p>
<p>Intercept: -0.056... | 25,333 |
<p>I am doing a (Heckman) probit. Some of my variables (e.g. N of employees, sales) are highly skewed (skew>2000). Do I need to take log-transformation to make them closer to normal?</p>
<p>Thanks!</p> | 69,080 |
<p>There is multiple-choice test and for every possible answer option my algorithm gives some score of how much it is likely to be the right one and picks the one with the maximal value as the answer.
If there are 4 options A B C and D and the corresponding scores are for example 3.34, 4.01, 2.78 and 3.01 then the an... | 29,365 |
<p>I would like to describe the "peakedness" and tail "heaviness" of several skewed probability density functions.</p>
<p>The features I want to describe, would they be called "kurtosis"? I've only seen the word "kurtosis" used for symmetric distributions?</p> | 69,081 |
<p>I performed interpolation on two elevation datasets. Is it possible to compare the two RMSE beyond just which one is larger and which one is smaller, to see if they are statistically different? </p>
<p>Thank you in advance for any help!</p> | 69,082 |
<p>Anyone's got a quick short educational example how to use neural networks (<code>nnet</code> in R for example) for the purpose of prediction? </p>
<p>Here is an example, in R, of a time series</p>
<pre><code>T <- seq(0,20,length=200)
Y <- 1 + 3*cos(4*T+2) +.2*T^2 + rnorm(200)
plot(T,Y,type="l")
</code></pre>... | 29,370 |
<p>I'm interested in variable selection for a cox proportional hazards model. </p>
<p>I've read <a href="http://arxiv.org/abs/1203.4928" rel="nofollow">this article</a> which slightly favours randomized bootstrap lasso selection over bootstrap lasso selection since it removes the necessity of selecting a lambda-value... | 69,083 |
<p>I've to do a check of goodness of fit in real-time in my software but I don't know how to implement it: I've got a sum of weighted chi-squared variable with 1 degree of freedom. I can do the approximation with a new chi-squared distribution multiplied by a constant, so I've got a gamma distribution with given parame... | 69,084 |
<p>I'm running a simple McNemar's test for agreement on the McNemar's example from Wikipedia. The test uses the following data:</p>
<p><img src="http://i.stack.imgur.com/w1CHJ.png" alt="table"></p>
<p>for patients of Hodgkin's disease. Running this SAS code:</p>
<pre><code>data hodgkins;
input hodgkins $ sibling $ c... | 29,373 |
<p>I have data with a minimum number of features that don't change, and a few additional features that can change and have a big impact on the outcome. My data-set looks like this:</p>
<p>Features are A, B, C (always present), and D, E, F, G, H (sometimes present)</p>
<pre><code>A = 10, B = 10, C = 10 ... | 29,374 |
<p>I've calculated the <a href="http://en.wikipedia.org/wiki/Mutual_information" rel="nofollow">Mutual Information</a> for my dataset using ARACNE, but I need to get p-values for each Mutual information. How do I calculate them? Is there any software for this calculation?</p> | 29,375 |
<p>I have two possible exposure variables (A and B) for use in a statistical model predicting a binary health outcome. I have fitted models with each variable separately and now know that one variable is a better predictor of my outcome based on a comparison of R-squared and BIC values. However, the ORs for the two va... | 29,376 |
<p>After reading thousands of articles on PCA and SVD, using them in a number of programming frameworks and even implementing similar techniques (like Random Indexing) I found out that I still have doubts about some parts of PCA for dimension reduction. So let me show what I know and what I have doubts about. </p>
<p>... | 69,085 |
<p>I have a binary variable with probit model, i.e., $P(Y_{ij}=1|X_j)= \Phi(a_i+b_iX_j)$, where $X_j$ is $\mathcal N(0,1)$, and $a_i$ and $b_i$ are regression parameters.</p>
<p>I am wondering what the expected value of $Y_j=\sum_{i=1}^n Y_{ij}$ is. Is there a known distribution for $Y_j$?</p> | 69,086 |
<p>Suppose $X_1, ..., X_n$ are $d$-ary discrete random variables which are part of a Bayes network, in which $X_i$ has $n_i$ parents. What is the number of parameters for the Bayes network?</p> | 39,505 |
<p>What are the modeling approaches depicted here? Can you name them and their prominent proponents or a landmark model? Is there an accepted superior approach? Who prefers which approach?
<img src="http://i.stack.imgur.com/64Pe4.jpg" alt="alt text">
(From: <a href="http://www.stat.duke.edu/~mw/fineart.html" rel="nofol... | 29,377 |
<p>I searched on Internet but cannot find any source about this. What is multiclass loss and what kind of metric is it? If someone can enlighten me, it will be appreciated. </p> | 29,378 |
<p>I am having trouble getting to the bottom of this concept for two types of questions (hw is already passed, but I have a test this week and would like to do better). Hopefully someone can help me get this through my thick skull.</p>
<p>Question 1</p>
<blockquote>
<p>In the following problem, check that it is ap... | 29,379 |
<p><a href="http://stats.stackexchange.com/questions/17407/how-to-digest-statistical-context">This question</a> illustrates the difficulty of a person mastering statistics and probability on their own, in the face of weakly developed resources like Wikipedia.</p>
<p>It occurred to me that consulting statisticians, and... | 39,507 |
<p>I am trying to understand how to use Bayes' theorem to calculate a posterior but am getting stuck with the computational approach, e.g., in the following case it is not clear to me how to take the product of the prior and likelihood and then calculate the posterior:</p>
<p>For this example, I am interested in calcu... | 39,514 |
<p>I have a series of functions, each one supposedly representing the density of a random variable across agents. Each function also has a domain, which describes what values of the random variable are valid.</p>
<p>Now, if I remember my stats classes correctly, if I take the integral of one of the functions across th... | 69,087 |
<p>Suppose I am building some predictive models and then creating a report detailing how "good" those models were in various ways. Is there a generic (maybe even non-technical) term for the various measures of correctness (e.g. precision, recall, etc.)? A layman might use "accuracy," but accuracy actually has a very ... | 69,088 |
<p>I'm a novice to data mining and started to read about it. What's the exact difference between experimental data and observation data? Both are obviously data; and many say observation data can lead to errors. But I guess it's not possible to do an experiment for all data sets. I'm really confused, explain me what is... | 39,517 |
<p>does it make sense to assume $u\sim N(0,\sigma^2)$ when I know from a histogram that $y$ is highly skewed. Because from the assumption $u\sim N(0,\sigma^2)$ it follows that $y\sim N(x\beta,\sigma^2)$ and I'm absoluteley not sure if the assumption $u\sim N(0,\sigma^2)$ makes sense in a case where I know that the dist... | 69,089 |
<p>Which setup is correct for a difference in difference regression model using </p>
<p>$Y_{ist} = \alpha +\gamma_s*T + \lambda d_t + \delta*(T*d_t)+ \epsilon_{ist}$</p>
<p>where T is a dummy which is equal to 1 if the observation is from the treatment group
and d is a dummy which is equal to 1 in the time period... | 595 |
<p>Suppose there is a data set $\{(x_i; y_i)\}_{i=1}^{N}, x_i \in \mathbb{R}^3, y_i \in \mathbb{R}$.</p>
<p>I am trying to find a regression function such as $f(x) = \omega_0 + \Sigma_{i=1}^{K} \omega_i \phi(\|x_i-c_i\|)$ using least square approximation.</p>
<p>And my question now is whether there are any difference... | 69,090 |
<p>I can't figure out how to do the following:</p>
<p>I need the following linear predictor
$\eta=team_i-team_j$
where, both $team_i$ and $team_j$ are categorical variables, which have 163 categories. Normally when using categorical variables you do the following:</p>
<pre><code>model<-glm(y~as.factor(team), famil... | 69,091 |
<p>As a follow on from here: <a href="http://stats.stackexchange.com/questions/69810/correlation-between-vegetation-and-erosion">Correlation between vegetation and erosion</a>, I am having some trouble with the type of data that I have. I am confused as to whether my four categories are ordered.</p>
<p>Specifically, m... | 69,092 |
<p>I have lot of records like this:</p>
<p><img src="http://i.stack.imgur.com/EmbqW.png" alt="enter image description here"></p>
<p><code>M</code> is about 10 million and <code>N</code> is about 100K.</p>
<p>Now I want to apply collaborative filtering on these data, for example, A user comes in with its features(spa... | 69,093 |
<p>I'm trying to assess the level of non-differentiation for a web survey I am doing. It features six pages of several Likert items on each page with a 6 point scale, followed by a seventh page of several items with a 10 point scale. </p>
<p>I'm looking for the best formula to evaluate non-differentiation, and partic... | 69,094 |
<p>I have a data set of $y$ values that is not particularly normally distributed. However, the $y$s do partially depend on several other parameters. A linear regression model $y=c+\mathbf{ \beta x}+\epsilon$ fits the data decently and the residuals look like they're normally distributed, have uniform variance vs. fitte... | 69,095 |
<p>I'm starting learning about clustering so perhaps this is a basic question. The idea is to generate clusters out of an array of floats, 1 dimension and N dimensions, get the mean value of each dimension of each cluster, and the array elements that get into a cluster should be within a range like this:</p>
<pre><cod... | 69,096 |
<p>I used the glmulti package in R to generate a linear model with interactions. The response variable has 21 observations, set against 5 input variables, one of which is a binary factor while the rest are continuous. The "best model" produced by glmulti, as judged according to aic, had 6 predictor terms (4 main effect... | 69,097 |
<p>Two dice are rolled. </p>
<p>Event A is all combinations for which the sum is greater than 9.</p>
<p>Event B is all combinations for which at least a face is 6. What are P(A|B) and P(B|A)?</p>
<p>Maybe you will find it very easy, but I couldn't come up with an answer based on using Bayes' theorem and not just wri... | 69,098 |
<p>Would you also be able to provide an example? I have very little mathematical/statistical knowledge and have never understood normalization.</p> | 9,409 |
<p>I am using <a href="http://www.stata.com/statalist/archive/2006-12/msg00564.html" rel="nofollow">this</a> module in Stata to calculate the CI of a series of number that have a inverse gaussian distribution. The problem is, while calculating the CI, the zeroes are being ignored and as a result the lower CI gets high... | 98 |
<p>I have a customer data set with the following data: </p>
<ul>
<li>The number of purchases that each customer made </li>
<li>The Date that they made each purchase </li>
<li>The Date that they signed up </li>
<li>The amount they spent on each purchase </li>
</ul>
<p>I want to segment my users into three groups: </p>... | 69,099 |
<p>I have two variables both are binary. </p>
<p>I would like to see how well one predicts the other. </p>
<p>Is it possible to do this in logistic regression? variables are coded as 0 and 1 but 1 does not indicate that something is 'correct'. can I still use logistic regression to see how well it is predicted?</p> | 29,388 |
<p><strong>Setup</strong></p>
<p>I found a paper on that has a varient on normal auto-encoders (contractive) which for its gradient uses the following regularization penalty:</p>
<p>$$\left|\left|J_f(x)\right|\right|^2_F = \sum_{ij}{\left( \frac{\partial h_j(x)}{\partial x_i} \right)}^2$$</p>
<p>where $\left|\left|... | 69,100 |
<p>I am running a logistic regression with dichotomous dependent variable (0-1) and with equal interval scale (1-5) as independent variable. The problem is that in order to arrive to meaningful results, i.e. reconcile with theory, I need to use the following transformation to independent variable: 1/log(x) .
The proble... | 39,527 |
<p>I'm trying to figure out how a single event affects sales numbers of a song. For example, see what the effect of being featured in iTunes store compared to songs with comparable previous download numbers.</p>
<p>How should I go about modeling this question?</p>
<p>Thanks!</p> | 32,225 |
<p>Please, prove that if we have two variables (equal sample size) $X$ and $Y$ and the <em>variance</em> in $X$ is greater than in $Y$, then the <em>sum of squared differences</em> (i.e., squared euclidean distances) between data points within $X$ is also greater than that within $Y$.</p> | 69,101 |
<p>I've been looking for resources on calculation of life expectancy uising Stata.</p>
<p>Combing Google results so far I've only been able to locate this module: </p>
<p><a href="http://ideas.repec.org/c/boc/bocode/s453001.html" rel="nofollow">LXPCT_2: Stata module to calculate multistate life expectancies</a></p>
... | 29,394 |
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