question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>I would love to get some advice regarding the following please!</p>
<p>I am involved in a study that is looking at cognition across 3 separate groups (1= the clinical group of interest; 2= clinical control group; 3=healthy control group). All participants completed a range of cognitive tests. Preliminary analysis o... | 73,563 |
<p>Say I have the following model:</p>
<p>$$\text{Poisson}(\lambda) \sim \begin{cases}
\lambda_1 & \text{if } t \lt \tau \\
\lambda_2 & \text{if } t \geq \tau
\end{cases}
$$</p>
<p>And I infer the posteriors for $\lambda_1$ and $\lambda_2$ shown below from my data. Is there a Bayesian way of ... | 73,564 |
<p>from what you have read or heard about, which is a good book on fuzzy logic/sets/systems? I'm interested in basic of fuzzy systems, fuzzification/defuzzification etc.</p>
<p>Thanks,
Lucian</p> | 47,395 |
<p>I do have a big list of numeric values (including duplicates) and I do want to group them into ranges in order to see if how do they distribute.</p>
<p>Let's say there are 1000 values ranging from 0 to 2.000.000 and I do want to group them. </p>
<p>How can I achieve this, preferably in Excel or SQL.</p> | 73,565 |
<p>Although I know how to calculate many of the statistical values, I have some difficulties understanding which one should I use in a specific situation. Here is my example:</p>
<p>In my experiment I tried to find out how fast does the Water evaporate from 8 different nonvowen Materials. To achieve this I prepared 4 ... | 73,566 |
<p>[I'm a stats noob, so please correct if I am going wrong somewhere!]</p>
<p>We run a survey of our customers based on certain events or touchpoints. The responses vary significantly by these touchpoints, so I would like to weight the responses by post stratification.</p>
<p>However, I have no responses from custom... | 73,567 |
<p>I'm currently trying to use Newey-West standard errors accounting for Heteroskedasticity and Autocorrelation with the sandwich package in R, but i lack understanding as i can not fully grasp the instructions provided in the manual.</p>
<pre><code>library(sandwich)
## fit investment equation
data(Investment)
fm <... | 73,568 |
<p>I'm trying to classify my set of data into two classes (introvert / extrovert). I was thinking of using a decision tree at first, but I don't have any potential known results in order to create my decision tree model. Thus I decided to use a <em>k</em>-means clustering algorithm with <em>k</em> = 2.</p>
<ol>
<li><p... | 35,966 |
<p>I would like to analyze my results which have 3 groups with 5 possible outcomes (they are ordinal data by the way) and the expected cell counts are less than 5. Seems like it is not possible to run a analysis larger than a 2X2 tables in SPSS. </p>
<p>Does anyone has a solution to it? Or should I consider using othe... | 73,569 |
<p>Suppose I run some models with following format.The dependent variable as the sum of realized values of a binary random variable over multiple trials, that is "number of yes votes on bills":</p>
<pre><code> Coef. SE z
(Constant) 0.467 0.239 1.950
SPD 0.094 0.174 ... | 73,570 |
<p>Suppose I have random variables $X_i$ which are Poisson distributed with mean $\mu$. I m interested in the sampling distribution of the variable $\frac{X_1+...+X_n}{n}$. We now that as $n$ goes to infinity, the distribution of mean is Gaussian. Assuming that I know the underlying distribution which is Poisson, is th... | 35,967 |
<p>I have already solved this question, but I need some feedback.</p>
<blockquote>
<p>A new method for measuring blood pressure in laboratory mice using radiotelemetry has been proposed. How does this compare with the existing method? You apply both methods to a sample of 16 mice and use <strong>________</strong>.</... | 35,968 |
<p>In my current dataset I have quite a few categorical variables.
Most have decent distributions between the categories. 30:40:30 splits etc. where these are percentage of dataset members per category</p>
<p>dataset is ~2000 members</p>
<p>But a fair few have either (I feel) useless or difficult distributions.</p>
... | 73,571 |
<p>Ideally, I would like to know the fraction of the mean of $x$ over the sum of the mean of $x$ and the mean of $y$:</p>
<p>$$\text{Fraction of interest} = \frac{\bar{x}}{\bar{x}+\bar{y}}$$</p>
<p>where $$\bar{x} = \frac{\sum_{i=1}^I x_i }{I}$$.</p>
<p>However, I have the fraction of the geometric mean of $x$ over ... | 28,559 |
<p>Deas,</p>
<p>One assumption for Spearman's correlation is that data have to be monotonic .. I tried to do scatterplot in spss, but I get the following graph that I couldn't decide if it is monotonic .. What is the solution please ? Note: my data are ordinal variables.</p>
<p><img src="http://i.stack.imgur.com/RZOU... | 35,970 |
<p>This might be a question in general: due to computational burden, I have to use a subset of my complete data (say, 1,000 out of the complete 10,000 observations) to get a p-value of a test. The test itself is from Monte Carlo simulations. My question is, is there a way to quantify the uncertainty of the p-value <str... | 73,572 |
<p>I'm doing a statistics paper in which I have to correlate the clinical diagnosis with the hystopathological one. So, basically I have one group of people with 2 different diagnosis:
1. clinical
2. hystopathological
Normally these two must be identical, but due to some clinical errors sometimes they aren't. My job is... | 73,573 |
<p>I have a homework assignment about implementing the adaboost algorithm.<br>
We are following this <a href="https://www.cs.princeton.edu/picasso/mats/schapire02boosting_schapire.pdf" rel="nofollow">article by Schapire</a>. I'm not exactly sure what they mean in the assignment by :</p>
<blockquote>
<p>Let the train... | 35,972 |
<p>From Berger&Casella, Chapter 8, Problem 8.5, page 402 for 2nd edition.</p>
<p>The problem is:
A random sample, $X_{i}$ is drawn from a Pareto population with pdf
$$
f(x|\theta,v)=\frac{\theta v^{\theta}}{x^{\theta+1}}I_{[v,\infty)}(x),\theta>0,v>0
$$
Show that the LRT of
$$
H_{0}:\theta=1; H_{1}:\theta\n... | 73,574 |
<p>In R, is it true that: </p>
<p><code>pt(q,df=Inf)</code> $=$ <code>pnorm(q)</code>? </p>
<p>Or in words, can I supply <code>df=Inf</code> in the cummulative t-distribution to get to the standard normal distribution function in R, as I should in theory?</p> | 35,974 |
<p>I am not clear about how exactly the p values and t values are used. I know how to calculate them but I am not clear about the basic concept behind them.</p>
<p>Any help ?</p> | 49,294 |
<p>A typical approach to solving a classification problem is to identify a class of candidate models, and then perform model selection using some procedure like cross validation. Typically one selects the model with the highest accuracy, or some related function that encodes problem specific information, like <a href="... | 28,579 |
<p>I have data that looks like this </p>
<p><img src="http://i.stack.imgur.com/2CdaI.png" alt="enter image description here"></p>
<p>I just want to predict the rest of 2013. What is the best way of doing this. </p>
<p>I used Excel's Forecast formula which uses linear regression. </p>
<p>I only have minor/very littl... | 140 |
<p>I have a situation where I want to test for differences between rows and columns in my data frame:</p>
<pre><code> ID Cond1A Cond1B Cond2A Cond2B
Sample1 2000 2311 2323 2324
Sample2 2424 1313 2324 4546
Sample3 1213 3413 2342 3353
</code><... | 73,575 |
<p>While studying relevance feedback(Pseudo relevance feedback), I have learn that the model can go horribly wrong for some queries. Can anyone give reasons why this is?</p> | 73,576 |
<p>I am using WEKA to do classification. I wish to compare with an existing paper that uses the Precision and Recall Break-Even performance as their results.</p>
<p>Can someone please help in order for me to determine this Break-Even performance? More preferably - if possible - with WEKA. If not, a formula I can use.<... | 73,577 |
<p>I wonder , if someone know the open source anomaly detection algorithm on computer log ?
For an example , computer log look like as mentioned below :</p>
<p>"value UL-CCCH-Message ::= { integrityCheckInfo { messageAuthenticationCode 0, rrc-MessageSequenceNumber 0 }, message cellUpdate : { u-RNTI { srnc-Identity 232... | 35,983 |
<p>I have general statistical question concerning the analysis of two-factorial experiments. I would like to compare several response variables (biovolume, richness etc.) of two experiments (homogeneous and heterogeneous) with the same factorial combination (dispersal x disturbance).</p>
<p>I guess a ANOVA or nested A... | 73,578 |
<p>I am conducting a study for analyzing male involvement in Family planning. It is of interest to develop an index for the involvement of male. I am currently having difficulties fitting an IRT model since my data has a lot of missing values and answers like "don't know" and some confusing answers. Note that my variab... | 35,985 |
<p>I have a single time series which will be divided on the date of the policy change before and after.
I want to compare the variances between the two time sections and I am told to do an F test of residual sum of squares.
How do I construct the F stat?
Do I run ARMA and get the residual sum of squares of the two time... | 73,579 |
<p>What's the entropy of the following generalized probability distributions?</p>
<p>$P_1(x) = \delta(x)$</p>
<p>$P_2(x,y) = \delta(x+y)$, for $0\le x\le 1$, and $P_2(x,y)=0$ otherwise.</p>
<p>Integrals of the type $-\int \delta(x) \ln\delta(x) \mathrm{d}x$ seem to diverge to $-\infty$ (see <a href="http://math.stac... | 73,580 |
<p>I am studying the Rocchio alorithm. I understand how it works. And typically we set Positive feedback is more valuable than negative feedback (so, set β < γ; e.g. γ = 0.25, β = 0.75).
<img src="http://i.stack.imgur.com/cIH7x.jpg" alt="enter image description here">
And many sytems allow only positive feedback whi... | 35,987 |
<p>To avoid reinventing the wheel, which approaches are known to extract product / service data from previously unknown webpages via machine-learning?</p>
<p>Which keywords in a search engine might give me better results about this topic?</p> | 35,988 |
<p>This one is bothering me for a while, and a great dispute was held around it. In psychology (as well as in other social sciences), we deal with different ways of dealing with numbers :-) i.e. <strong>the levels of measurement</strong>. It's also common practice in psychology to standardize some questionnaire, hence ... | 73,581 |
<p>I have a large set of data points received by experimentation and each point has n ,or let's say 8 in this case, independent variables and one output/dependent variable.</p>
<p>(x1, x2, x3, ...., xn) = y --> some measured output </p>
<p>How would I fit a "curve" through these points or interpolate with the data po... | 73,582 |
<p>I'm designing a multi class classifier (for 4 classes) using <strong>Discrete HMMs with States N and Symbols M</strong> for each of the HMM.</p>
<p>However, I found that recognition performance(i.e highest log likelihood) of a specific class depends upon the <strong>N and M</strong> with which it was trained.</p>
... | 73,583 |
<p>I am looking for a good and modern Kernel Regression package in R, which has the following features:</p>
<ol>
<li>It has cross-validation </li>
<li>It can automatically choose the "optimal" bandwidth</li>
<li>It doesn't have random effect - i.e. if I run the function at different times on the same data-set, the res... | 35,990 |
<p>I was wondering if there under some circumstances is possible for ANN's to perform better if you prune away some connections on them as for example:</p>
<p>Constructing one ANN by taking two multi-layered ANN's A and B in parallel (same input and output nodes) adding a few "communication" connections between the hi... | 73,584 |
<p>I need to conduct an experiment and use one-way ANOVA test to analyze the data. I know what the test is, but I am having difficulty figuring out an experiment to perform. Any suggestions on an experiment? Something simple I can do at home.</p>
<p>Thank you</p> | 29,538 |
<p>Looking at the Heritage Health Prize, the data is structured as follows:</p>
<blockquote>
<p>Each of the Data Sets will be comprised of tables as follows:</p>
</blockquote>
<pre><code>a. Members Table, which will include:
i. MemberID (a unique member ID)
ii. AgeAtFirstClaim (member's age when first claim... | 47,432 |
<p>I know <code>glmnet(x,y)</code> generates $\lambda$ but I am very curious to know the actual formula that is behind this, generating $\lambda$. </p> | 35,994 |
<p>I am trying to approximate a certain factor in my graph.
<img src="http://i.stack.imgur.com/mvX9h.jpg" alt="enter image description here"></p>
<p>Following Tom Minka's tutorial what I have to do is as follows:
$$
\prod_{i=1}^3 q_{w_i}(\pi_2)\approx \int p(\pi_2|w_1)q_{\pi_1}(w_1)\prod_{i=1}^3 q_{D_i}(w_1)\, dw_1\,... | 73,585 |
<p>I have a regression model with 3 different variables. One variable is only significant if I square it, and not include the linear version i.e. $Y = \beta_1X_1 + \beta_2X_2 + \beta_3X_3^2$</p>
<p>How should I interpret the $X_3^2$ variable?</p> | 49,477 |
<p>The may sound like a strange question but I was wondering if a Pseudoinverse of a matrix could be found using SVD whether there was a graphical modelling equivalent that could be used to estimate the inverse of a matrix. </p> | 73,586 |
<p>A question from a harried doctoral candidate working on dissertation revisions.</p>
<p>What is the current opinion about how to include and interpret 3-way interactions in linear models? If the p-value for a 3-way interaction is not meaningful to interpret, how does one address--both substantively and empirically--... | 73,587 |
<p>Suppose we have n by n covariance matrix of n normal random variables. Is there program where we plug in sample values for k of the n variables and the program, by using the covariance matrix and these k values, generates samples for the remaining n-k variables ?</p> | 35,997 |
<p>I Have a variable (time series) which is nonstationary. I found that from the graph which seems to have a stochastic trend and the correlogram has a typical nonstationary pattern.
After that, I've been asked to find the parsimonious ARMA model (using information criteria), and by following the Box-Jenkins methodolo... | 17,811 |
<p><strong>A definition before I start:</strong> </p>
<p>A trajectory $t$ of length $n$ is here defined as a series of 2D coordinates $$\{(x_1,y_1), (x_2, y_2),..., (x_n, y_n)\}$$
Now I have a set comprised of such trajectories denoted by set $T=\{t_1, t_2,...,t_n\}$. </p>
<hr>
<p>Take $t_1$ and $t_2$ as an example:... | 73,588 |
<p>I'm developing prediction model based on PLS (partial least squares) analysis.
I'm looking into variation captured by X(R square X), R square Y, number of components and accuracy after using cross validation, in the process of model development.</p>
<p>Can anybody suggest me what should be the approach to trade of... | 73,589 |
<p>I am fitting curves to my data to extract one parameter. However, I am unsure what the certainty of that parameter is and how I would calculate / express its $95$% confidence interval.</p>
<p>Say for a dataset containing data that exponentially decays, I fit a curve to each dataset. Then the information I want to ... | 25,042 |
<p>I'm new in the page and pretty new in statistics and R. I'm working on a project for college with the objective of finding the correlation between rain and water flow level in rivers. Once the correlation is proved I want to forecast/predict it.</p>
<p><strong>The data</strong>
I have a set of data of several years... | 73,590 |
<p>I have 17 patients who underwent cervical plating, I have calculated </p>
<ol>
<li>preoperative cervical measurements like angles at certain level to be operated, total cervical angles </li>
<li>same parameters calculated after operation </li>
<li>same parameters calculated after 2 years of operation</li>
</ol>
<p... | 73,591 |
<p>I have the following data for 10 subjects based on before and after measurements:</p>
<pre><code>x <- c(12.9, 13.5, 12.8, 15.6, 17.2, 19.2, 12.6, 15.3, 14.4, 11.3)
y <- c(12.7, 13.6, 12.0, 15.2, 16.8, 20.0, 12.0, 15.9, 16.0, 11.1)
</code></pre>
<p>and would like to perform a permutation test.</p>
<p>I used... | 73,592 |
<p>I have a dataset collected using an accelerometer. I am extracting the magnitudes from the signal to find the difference in running pattern between two different running surfaces. Will normalization help to improve my classification accuracy? In general, when should we normalize time series data? Any suggestions?</... | 73,593 |
<p>Is there a term(s) for calculating the variance or standard deviation from a value other than the mean?</p>
<p><strong>Example:</strong></p>
<p>If I have a set of estimates for jelly beans in a jar, calculating standard deviation and variance is an operation on the mean of those estimates. However, I also want to ... | 41,344 |
<p>Objective is to predict a car's retail value based on the characteristics of mileage, make, model, engine size, interior style, and cruise control.</p>
<hr>
<h2>Price</h2>
<p>The price of the vehicle </p>
<hr>
<h2>Cylinder</h2>
<p>4,6,8</p>
<hr>
<h2>Liter</h2>
<p>How many liters the engine is</p>
<hr>
<h2... | 37,451 |
<p>I'm looking for resources (articles, books or just suggestions) on cyclostationary time series parameter estimation. I have a 2D signal of that sort, which forms a grid. </p> | 36,002 |
<p>I am using the <code>mda</code> package and in particular the <code>fda</code> routine to classify in term of gear a set of 20 trips. I preformed a flexible discriminant analysis (FDA) using a set of 151 trips. </p>
<pre><code>FDAT1 <- fda(as.factor(gear) ~ . , data =matrizR)
</code></pre>
<p>A total of 22 pre... | 73,594 |
<p>Suppose you had a bag with $n$ tiles, each with a letter on it. There are $n_A$ tiles with letter 'A', $n_B$ with 'B', and so on, and $n_*$ 'wildcard' tiles (we have $n = n_A + n_B + \ldots + n_Z + n_*$). Suppose you had a dictionary with a finite number of words.</p>
<p>You pick $k$ tiles from the bag without repl... | 73,595 |
<p>What would be the MLE (Maximum Likelihood Estimator) of the given data:</p>
<p>Assuming the i-th point $ {p}_{i} = ({x}_{i}, {y}_{i}) $.<br>
We have the following measurements of this specific point - $ (x, y, r = \sqrt{{x}_{i}^{2} + {y}_{i}^{2}}) $.<br>
Namely, we have a measurement of the x, y coordinate and the ... | 73,596 |
<p>I am analyzing rna-seq data in the format of counts. There is batch effect revealed by PCA. </p>
<p>One method I tried called <strong>RUVseq</strong>, it estimated the variation basing on control genes, and then added it to design matrix. I don't know why simply adding a continuous variable will work.</p>
<p>Here ... | 73,597 |
<p>This has been originally asked at <a href="http://math.stackexchange.com/questions/480703/most-common-subgroups?noredirect=1#comment1035243_480703">math.stackexchange</a> where it was suggested that I try Cross Validated.</p>
<p>My background is not mathematics. This is an IT problem that may have a mathematical so... | 73,598 |
<p>I am performing 5-fold cross-validation on a relatively large data set and I have noticed that the validation error for each of the 5 training sets are very similar. So I guess, in this case, cross-validation is not very useful (it would be about the same as just using one training and test set). So I was wonderin... | 73,599 |
<p>I'm reading Newey & McFadden - Large sample estimation and hypothesis testing (in the <a href="http://rads.stackoverflow.com/amzn/click/0444887660" rel="nofollow">Handbook of Econometrics, Volume 4</a>, 1994, page 2178).</p>
<p>My model which I'm interested in has some former estimation done before the estimati... | 31,131 |
<p>Let X, Y, Z be i.i.d. distributed Gamma random variables. What could the mode of the vector $(X, X+Y, X+Y+Z)$ be?</p>
<p>Does the mode of a random vector equal the combination of the marginal modes?</p> | 36,008 |
<p>I'm trying to understand the properties of Mahalanobis distance of multivariate random points (my final goal is to use Mahalanobis distance for outlier detection). My calculations are in python.
I miss some basics here and will be glad if someone will explain me my mistake.</p>
<p>Here is my code:</p>
<p>First I ... | 73,600 |
<p>I have an explanatory variable that is transformed as suggested in footnote 25 of <a href="http://www.federalreserve.gov/pubs/feds/2013/201353/201353pap.pdf" rel="nofollow">the article</a> as follows (the explanatory variable is continuous and can take negative, zero or positive values)
\begin{equation}
y=\text{sign... | 36,010 |
<p>I'm trying to understand how I might best model a variable where over time I've obtained increasingly detailed predictors. For example, consider modeling recovery rates on defaulted loans. Suppose we have a dataset with 20 years of data, and in the first 15 of those years we only know whether the loan was collateral... | 73,601 |
<p>I have a specific question about random selection, representativeness and inference. It is well known that it's necessary to use random selection to get representative samples from the population of interest. But what happens with non-random samples? </p>
<p>I am working with an intentional sample. I compared the m... | 25,048 |
<p>When estimating power calculations for a case control study, what does exposure of controls really mean? </p>
<p>I find lots of information how how to calculate exposure for cases when you already know exposure in controls - but nothing on how the actual number is calculated for controls. </p>
<p>Please enlighten ... | 73,602 |
<p>this is my first post, so I hope everything is in the right format. I have some problems with glmer and don't know how to fix it, so I hope somebody can help me out with this. I could not find an answer to this anywhere.</p>
<p>My experiment: The experimental setup has eight sites, each site has a central area in w... | 73,603 |
<p>I'm doing a Support Vector Regression with about 70k samples with 500 features each. I'm using sklearn implementation of SVR and my input for the train set is a sparse matrix.
But, for my surprise, the training with Linear Kernel is taking a huge amount of time, a lot more than the training with RBF Kernel.</p>
<p>... | 73,604 |
<p>Let $X_1, \cdots, X_n$ be $iid$ normal random variables with unknown mean $\mu$ and known variance $\sigma^2$. How to find $E[\Phi(\bar X)]$, where $\bar X:=\frac{\sum_{i=1}^nX_i}{n}$, please? I guess the answer should be $\Phi(\mu)$. Here is how I started. Note that $Y:= \bar X$ is also normal with mean $\mu$ and v... | 49,565 |
<p>Recently, randomly browsing questions triggered a memory of on off-hand comment from one of my professors a few years back warning about the usage of ratios in regression models. So I started reading up on this, leading eventually to Kronmal 1993.</p>
<p>I want to make sure that I'm correctly interpreting his sugge... | 41,280 |
<p>I am reading a book on linear regression and have some trouble understanding the variance-covariance matrix of $\mathbf{b}$:</p>
<p><img src="http://i.stack.imgur.com/RIgsS.png" alt="enter image description here"></p>
<p>The diagonal items are easy enough, but the off-diagonal ones are a bit more difficult, what p... | 73,605 |
<p>I'm trying to reproduce a derivation of the cokriging equations that involves the cross covariance and the cross variogram. This derivation is included in the Multivariate Geostatistics by Wackernagel. However, I can't reproduce the following result:</p>
<p>\begin{align}{}\sigma_{E}^{2} &= \sum_{i=1}^{N} \sum_{... | 73,606 |
<p>What statistical analysis would I use when testing 35 participants. pre & post test and checking for changes after 1 intervention and a control group with no intervention?
I have one mediating variable, 3 independent variables and two dependent variables.</p> | 73,607 |
<p>I am playing with <code>scikit-learn</code> to find the <code>tf-idf</code> values. </p>
<p>I have a set of <code>documents</code> like:</p>
<pre><code>D1 = "The sky is blue."
D2 = "The sun is bright."
D3 = "The sun in the sky is bright."
</code></pre>
<p>I want to create a matrix like this:</p>
<pre><code> Do... | 36,015 |
<p>I'm working on a project and I would like to know if the following strategy is good/correct. Sorry if this is a basic/stupid idea (I'm new to this).</p>
<p>The input is a dataset with 2.500 features and 1.000 instances. I have to apply a feature selection on this set. In the beginning I randomly make a learning set... | 73,608 |
<p>I wonder how to compute precision and recall using a confusion matrix for a multi-class classification problem. In specific, one observation can only be assigned with most probable class / label. </p>
<p>I would like to compute </p>
<ul>
<li>Precision = TP / (TP+FP) </li>
<li>Recall = TP / (TP+FN)</li>
</ul>
<p>... | 73,609 |
<p>I conducted a panel OLS regression using gretl, on a balanced panel with around 25 zones and 10 time periods. I would like to use the model to forecast future values of y (dependant variable), given known future changes of x (explanatory variable).</p>
<p>I would like to ask: how to deal with (a) the constant, (b) ... | 73,610 |
<p>Suppose I have $X,Y$, which are independent random variables. </p>
<p>Why is it that $E(\frac{X}{Y}) = E(X)E(\frac{1}{Y})$? </p>
<p>Also, why is it that $E(X^2Y^2)=E(X^2)E(Y^2)$? How is it that the square of an independent random variable is also independent in relation to $Y$ or $Y^2$? Thanks! </p> | 73,611 |
<p>I have two sets of a longitudinal data that I hypothesize to measure same latent construct.I am trying to test this hypothesis using Structural equation modelling technique. Basically, I am trying to use confirmatory factor analysis in longitudinal data using SEM. My models are relatively simple CFA models.</p>
<... | 73,612 |
<p>I am working with R package "muhaz" to get the kernel estimate of the hazard function. If we have the following example which is the sample of uncensored data:</p>
<pre><code> x =c(0.001409591, 0.008451294, 0.019719245, 0.046626865 ,0.244813744,
0.410032119, 0.489286425, 0.697342699, 0.731541987, 0.954493... | 73,613 |
<p>Almost in all texts which are discussing theorems of statistical learning, they assume analyzing arbitrary unknown distribution (the worst case). But in practice different problems (different data) have different levels of hardness, for example linear separable data is easier to learn than the data that are less (or... | 73,614 |
<p>With respect to post <a href="http://stats.stackexchange.com/questions/7977/how-to-generate-uniformly-distributed-points-on-the-surface-of-the-3-d-unit-sphe">(1)</a> and post <a href="http://math.stackexchange.com/questions/87230/picking-random-points-in-the-volume-of-sphere-with-uniform-probability">(2)</a>, I gene... | 73,615 |
<p>For example, the standard deviation is known to have bias that depends on the number of samples observed. If I wanted to do Bayesian inference on the SD of samples from two populations, and have unequal sample sizes from each, would the resulting inference take this bias into account?</p>
<p>(Yes, I'm aware that th... | 25,055 |
<p>This is a real small business problem, not a homework problem.</p>
<p>A monthly production goal is 60000. We want to be sure that say 95% of months meet this goal.
The goal is a minimum, so we want to be sure we aren't under this, but we don't care how much we are over.</p>
<p>We want to use daily production as a ... | 73,616 |
<p>Suppose $a_1 = b + c_1$ and $a_2 = 2b + c_2$ where $b, c_1, c_2$ are all $N(0,1)$</p>
<p>Find $E[b|a_1,a_2]$</p>
<p>My attempt:
As $E[b] = 0$, I assume $E[b|a_1, a_2] = 0$. Is this a logical assumption?</p> | 73,617 |
<p>I'm reproducing an example from <a href="http://rads.stackoverflow.com/amzn/click/0470073713" rel="nofollow">Generalized, Linear, and Mixed Models</a>. My MWE is below:</p>
<pre><code>Dilution <- c(1/128, 1/64, 1/32, 1/16, 1/8, 1/4, 1/2, 1, 2, 4)
NoofPlates <- rep(x=5, times=10)
NoPositive <- c(0, 0, 2, 2,... | 73,618 |
<p>I own a url shortening service. I want to deliver only legitimate statistics to my clients. There are possible scenarios that a particular user writes a script to automatically open the shortened URL, thus making the statistics look bad. What are the approaches one can follow to detect if a click is legitimate or no... | 73,619 |
<p>From <a href="http://cran.r-project.org/web/packages/epiR/epiR.pdf" rel="nofollow">epiR manual</a> for <strong><em>epi.2by2</em></strong> function:</p>
<blockquote>
<p>units: multiplier for prevalence and incidence estimates.</p>
</blockquote>
<p>In examples it is set to 100, <code>units=100</code>. What does it... | 73,620 |
<p>I know this might be a little ropey, statistically, but this is my problem.</p>
<p>I have a lot of range data, that is to say the minimum, maximum and sample size of a variable. For some of these data I also have a mean, but not many. I want to compare these ranges to each other to quantify the variability of each ... | 73,621 |
<p>Give the following table</p>
<pre><code> Male | Female | Total
Likes 10 | 3 | 13
Indifferent 20 | 20 | 40
Dislikes 10 | 9 | 19
Total 40 32 72
</code></pre>
<p>Here the independ... | 73,622 |
<p>I'm trying to understand the assumptions of different parameterizations in a Markov network. In this case, I'm trying to understand the assumptions (and effects) that result from parameterizing pairwise potentials with pairwise frequencies (i.e., $\psi_{(a, b)} = p(a, b)$), which the authors use in:</p>
<p>Mitrofan... | 73,623 |
<p>I am a little new to neural network. I have two questions:
1. Can we use neural network in the small $n$ large $p$ situation?
2. Any regularization methods designed for parameter elimination? (Shrink some $\omega$ to 0). For example to add $L_1$ regularizer as Lasso? I know some methods for avoiding over-fitting, (w... | 73,624 |
<p>I have two columns of data, and would like to show their differences through the visualization approach. The current issue is that these two columns are in-fact very close to each other. In other words, I would like to zoom in the minor differences that are existed using a graphical way. Are there any suggestions? T... | 36,029 |
<p>How can I fit a copula for a bivariate vector of negative binomial and Bernoulli margins?</p>
<p>I would prefer a Frank or Clayton copula.</p> | 39,251 |
<p>I have a HLM model with significant variance in the level 1 intercepts across groups but no significant variance in the level 1 slopes across groups and find significant cross-level moderation effects. Does it make sense to interpret these or are random slopes a necessary condition for probing cross-level interactio... | 73,625 |
<p>Suppose I have to estimate 3 models:</p>
<p>$y_1 = y_2\beta_1 + y_3\beta_2 + X\beta_3 + u_1$</p>
<p>$y_2 = y_1\alpha_1 + y_3\alpha_2 + X\alpha_3 + u_2$</p>
<p>$y_3 = y_1\gamma_1 + y_2\gamma_2 + X\gamma_3 + u_3$</p>
<p>I account for the endogeneity of $y_1, y_2$ and $y_3$ with a approach which creates a additiona... | 36,030 |
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