question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>The setup: I am testing, if different instructions on playing a game result in different outcome. The game has fixed amount of N different possible outcomes. (I most likely set N to something around 2-5). The outcomes are measured on categorical scale (each possible outcome being one category).</p>
<p>Lets say I ha... | 71,079 |
<p>I plan to include coordinates as covariates in the regression equation in order to adjust for the spatial trend that exists in the data. After that, I want to test residuals on spatial autocorrelation in random variation. I have several questions:</p>
<ol>
<li><p>Should I perform linear regression in which only ind... | 43,089 |
<p>I am confused by two, yet inconsistent for me, facts: Since the PLS regression is expressed by matrices of scores and loadings as
$$X=TP^T+E\\Y=UQ^T+F$$
how it can be translated into linear equation like $Y=a+b_1X_1+b_2X_2+...+b_nX_n$?</p>
<p>(I have found this in several papers).</p> | 32,370 |
<p>I just need a direction on which regression algorithm (preferably glm or similar) algorithm to use when the predictor variables are a mix of numerical and categorical variables. The output is numerical for the time being but in future, I need to extend this for categorial output also. </p>
<p>My input columns are ... | 71,080 |
<p>I was wondering if I can categorize the factor saved scores by taking their quartiles (or some other measures, I am not sure what should I use!) as cut points and use them as predictors in an ordinal logistic regression.</p>
<p>The reason I am thinking of doing so is that, the number of empty cells increases to a l... | 45,442 |
<p>I have the following timeseries</p>
<p><img src="http://i.stack.imgur.com/Q6Qld.png" alt="enter image description here"></p>
<p>obtained using the data posted below.</p>
<p>For a sliding window size of 10, I am trying to compute the KL-divergence between the PMF of values within the current sliding window and the... | 71,081 |
<p>We performed a biomechanical study, comparing an intact state to 5 different deficiency states on the same knee cadaver specimen. This was conducted on a very small sample size (n=8). My problem is, that some of the 5 deficiency variables are not normally distributed. My original plan was to compare each of the defi... | 71,082 |
<p>Do we look at the absolute value of the leverage or the relative value? </p>
<p>For instance, based on the chart below, the largest leverage is about 0.023, it is big compared to other data points, but I'm not sure if there's something like threshold in VIF that indicating a high leverage? </p>
<p><img src="http:/... | 71,083 |
<p>I am simulating two fair coins and running a <code>prop.test</code>, how come increasing number of trials doesn't decrease false positive? I'm suspecting it's in some underlying assumptions in the R functions that I'm using which I missed.</p>
<p>This binomial coin flip simulator takes argument N, for number of tri... | 71,084 |
<p>I'm doing a project to predict probability of delinquent for individual loans. Seems the model I fit is not good and I want to improve the model. However, I'm confused by the results I got and don't know what to do next. Can anyone kindly give me some instructions on the project? </p>
<p>The outcome is binary, wher... | 32,374 |
<p>I apologize that this seems to be a half function-specific, half stats question.</p>
<p>I'm conducting a set of multivariate analyses using the adonis function from the vegan package in R - distance-based permutational manova. Predictor variables are mixed continuous and categorical. I'm using the same predictors t... | 71,085 |
<p>I am trying to fit a dataset using the standard NNLS (non-negative least squares) approach.
Formally:</p>
<p>$\min_x ||Ax-b||^2_2$ s.t. $x\ge0$</p>
<p>This is a quadratic program and can be solved optimally. The solution I find fits the data reasonably well and is relatively sparse (which is good for me) but has a... | 43,098 |
<p>How can you calculate the granger causality between x(t) and y(t) when you have only been given two equations and no data? I have been stuck on this for a while.
Any help will be really appreciated. </p> | 71,086 |
<p>I have got a problem about doing a classification. I have got around 50 datasets. Each of them has 15 features.</p>
<p>I am trying to use these features to classify the 50 datasets to either 'Good' or 'Bad'. The ground truth labels of the 50 datasets are available so that a classical training and validation can be ... | 71,087 |
<p>Just wondering if we can use MCA (Multiple Correspondence Analysis) to predict new cases's classification? </p>
<ol>
<li><p>Map new cases on to the Biplot to see which direction on the axes it is closer to?</p></li>
<li><p>How do we calculate the distances of the new cases?</p></li>
</ol>
<p>Is there a way to imp... | 32,376 |
<p>I have a corpus of 2500 opinions, is it posible to use scikit´s restricted boltzmann machine implementation to extract a feature vector as a previous step to a classification task?. What aproach do i need to follow in order to use a restricted boltzman machine for text classification?, do i need to label my data to ... | 939 |
<p>In machine learning, it is often assumed that a data set lies on a smooth low-dimensional manifold (the manifold assumption), but is there any way to prove that assuming certain conditions are satisfied, then the data set is indeed (approximately) generated from a low-dimensional smooth manifold?</p>
<p>For example... | 71,088 |
<p>I have a data set with school level measures including test score percentiles. These percentiles are central to my analysis. For example, one measure is the test score of the 25th and 75th percentile student at that school. Likewise I have data on race that needs to sum to 100. I have missing data and want to use mu... | 71,089 |
<p>I have 3PL model parameters (guessing, difficulty and discrimination item parameters).
Is there any function with which I can estimate individual ability from item response data?
I tried the function <code>factor.score</code> in the package <a href="http://cran.r-project.org/web/packages/ltm/index.html" rel="nofoll... | 71,090 |
<pre><code>library(ISLR)
lm.fit = lm(mpg[-1]~weight[-1], Auto)
predict(lm.fit, data.frame(weight = Auto$weight[1]))
</code></pre>
<p>Why does this code cause the following error:</p>
<pre><code>Warning message:
'newdata' had 1 row but variables found have 0 rows
</code></pre>
<p>It doesn't cause an error for any oth... | 71,091 |
<p>I am performing ordinal regression, I have 5 response categories and several predictors both continuous and categorical. I would like to add a predictor which is categorical but ordered (1, 2, 3, 4). I don't think it would be appropriate to apply the usual dummy coding for unordered categorical predictors, but when ... | 71,092 |
<p>I have 1000 of data of mean temperature and daily rainfall of specific area. I need is to make a graph by using R software. I had already made the structure and summary of those given data. Now I have to make bins of 10 sets of temperature data and determine the 95th percentile rainfall of each bins. Next is to do t... | 32,381 |
<pre><code>memb float %9.0g proportion of permanent employees who are
members of the worker cooperative
bonus float %9.0g average distributed profits per worker in
mil... | 32,382 |
<p>I would like to ask how I can illustrate that Fisher's distribution when the null hypothesis is right goes to $F(k-m,n-k)$ when the degrees of freedom grow.</p>
<p>How exactly is $F$ calculated in this case? And what is $k$? Should I use Wald test here? (It's assumed that errors have t distribution.)</p> | 38,178 |
<p>I need a simple bar chart or the like. I am not a statistician by any means, but this chart is supposed to accurately represent FileIO in MB/s compared to the theoretical peak of a specific drive.</p>
<p>The first value is always 30,000.<br>
The second value is variable, but leans towards the extremely low 1–10 tho... | 32,384 |
<p>I am trying to run rknn with rknn package but it appears an error I am not able to understand. Here's the code and the error:</p>
<pre><code>rknn(bank_training, bank_testing, y_n, k=2, r=100, mtry=4)
Error in knn(train = data[, fset], test = newdata[, fset], cl = y, k = k, :
too many ties in knn
</code></pre>
<... | 32,385 |
<p>I need to implement a program that generates a sample from a really complicated distribution $f$ of 3 variables. I need to implement it using Metropolis-Hastings Algorithm's and its variation and I was thinking to use Metropolis Random Walk with a multivariate Normal distribution. But to use Random-Walk, the proposa... | 71,093 |
<p>Hey I have a question that I found in a textbook for some practice before a test, but there aren't any solutions for it. I'm pretty sure it's related to testing a hypothesis, but I'm not sure. </p>
<p>If anyone can point me into the right direction of solving this that would be great. </p>
<p>Q1: Five soft drink... | 18,348 |
<p>Kindly advise what the value we obtain for Tarkkonen's rho tells us about - reliability or validity of the data being measured.
Thank you</p> | 71,094 |
<p>Does anybody know how to interpret a whole bunch of effects (main and interaction) in a clever way? Or does anybody have a good example where it's shown? </p>
<p>To be more precisely: Assume that you have a lot of effects in your model (main and interaction effects) and you know that standard errrors and coefficien... | 38,330 |
<p>How can I use bayesian statistics for adwords clicks modelling? Is there any good source to learn about it?</p> | 71,095 |
<p>I am writing a Gibbs sampler for data that is Log-Normal (LN) distributed, with unknown mean and variance. There is a wealth of information on inference for LN models when either the mean or variance (precision) are known, but I'm not finding much information on inferring both parameters. I have an idea of "reasonab... | 71,096 |
<p>When we study differences between a treatment and control group in an experimental setting, we want to test whether those differences are big enough that we can conclude they are not simply due to chance.</p>
<p><em>(Lacking official terminology for the some concepts below [especially #2], please either grant me a ... | 32,389 |
<p>I'm conducting a retrospective study to assess the efficacy of a new test for predicting sudden cardiac death (SCD). I also want to compare the accuracy of my new predictor with that of a conventional predictor. I'm not a statistician, so I would very much appreciate it if any of you experts can confirm that I'm in ... | 32,391 |
<p>I am analyzing a segregating population of plants coming from an hybridization process.
The experiment consists in several field plots (according to an augmented design). In each plot a segregating population coming from an hybrid plant was seeded. Therefore, the plants into each plot are segregating. I defined sev... | 71,097 |
<p><a href="http://ops.fhwa.dot.gov/publications/fhwahop08024/chapter6.htm" rel="nofollow">Traffic light synchronization</a> nowadays is not a tedious project, Image: </p>
<p><img src="http://i.stack.imgur.com/KtnTF.png" alt="image"></p>
<p>For a personal research project I'm trying to build a statistical model to so... | 71,098 |
<p>I'm searching for a model that can be used to decompose incremental effects and baseline effects and is also good at prediction (i.e. Not OLS). We have tried OLS, ARIMAX with exogenous factors, ARIMAX with exogenous factors which includes media impacts, and regional ARIMAX models (estimated regionally then summed up... | 32,394 |
<p>I was wondering if anyone here could help me with the following:</p>
<p>I estimate a standard Bayesian VAR with Normal-Inverse Wishart priors. I identify some policy shock in it, and then derive the IRF for variable x1 to this policy shock. This IRF for x1 is the mode of posterior distribution as suggested by Inoue... | 753 |
<p>I've seen a little bit here about the difference between statistical inference for random samples, and what happens when we actually have population data. Most arguments seem to suggest you "never actually have the population" and the population data you think you have represents some unobservable super population w... | 43,119 |
<p>Out of one pool, I've randomly selected a small group (group A) and put everyone else in group B. Then, I'm observing whether or not they take a desired action.</p>
<p>If I'm looking to test at a 95% confidence, what's the best methodology and stats test to use? I read that with a large enough sample, it's ok to us... | 43,323 |
<p>I have run the General Linear Model in SPSS to analyse the effect of several demographic variables (e.g. gender, age) on the relationship between X and Y. </p>
<p>So essentially, this is an analysis to see if there is a significant interaction between (for example) age and X on Y. (Also called moderator effect)</p>... | 43,124 |
<p>How can I fit a logarithmic regression equation of form $y=a+b (\log (x_1)) + c(\log(x_2))$ on a data set using R?</p>
<p>Here the main concern is that data contain zeros multiple times, so R will give infinity in the output.</p>
<p>I have tried adding some constant to the $x$ variables, such as <code>log(x1+0.0... | 43,125 |
<p>I am new to Bayesian estimation. The assumption that the parameters are random variables seems a little unsettling to me. For example when considering a model for data, what physical interpretation can I provide to the equation</p>
<p>$$
\begin{eqnarray*}
P(Data) & = & \sum_{\theta} {P(Data,\theta)} \\
... | 71,099 |
<p>I am looking at the distribution of the sum of squares of T-distributed random variables, with tail exponent $\alpha$. Where X is the r.v., the Fourier transform for $X^2$, $\mathscr{F}(t)$ gives me a solution for the square before the convolution $\mathscr{F}(t)^n$.
$$\mathscr{F}(t)=\int_0^{\infty } \exp \left(i\,... | 71,100 |
<p>I've been reading about hidden Markov models, and I'm interested in both discrete and continuous time models (and discrete states). I have found many papers on the discrete time HMM, but not the continuous time HMM. I really want to know how to to set up the model and estimate the parameters. </p>
<p>Does anyone kn... | 71,101 |
<p>I would like to do an intervention analysis to quantify the results of a policy decision on the sales of alcohol over time. I am fairly new to time series analysis, however, so I have some beginners questions.</p>
<p>An examination of the literature reveals that other researchers have used ARIMA to model the time-... | 71,102 |
<p>I know I have seen some research, perhaps in the contexts of time-varying topic models, on the popularity of Bayesian methods in statistics and machine learning over the last 20 years. Unfortunately I cannot seem to find the citation. Does anybody know a paper that includes a plot over time of the popularity of Ba... | 71,103 |
<p>I am looking for an introductory to intermediate level book on Generalized Linear Models. Ideally, in addition to the theory behind the models, I would want it to include applications and examples in R or another programming language - I hear SAS is also a popular choice. I intend to study it on my own and so it wou... | 71,104 |
<p>I use two criterion ($w$ and $x$) for predicting the outcome of football matches. Analysis of historical records has provided me with two best fit linear equations. The probability that the team playing at their home ground will win based on criteria w, is $y_1 = 0.02w + 0.38$. A different probability based on $x$ i... | 43,134 |
<p>I would like to use data mining to try to find a good workout schemes. The input dataset will contain the parameters of a set of workouts with dates and different performance and medical measures. The problem is that the influence of each individual workout will be different depending on the time that has passed aft... | 71,105 |
<p>I'm working on a life insurance problem: trying to simulate the total dollar amount of claims in a year. To do this, I have a record for each person that contains their amount of insurance and an estimate of the probability that they will make a claim during the next year. I have run thousands of one-year simulat... | 71,106 |
<p>I have a two-dimensional predictor plane, 0-1-Observations and a priori knowledge of minimal probabilities per combination of the predictors. I would like to fit a model (e.g. GAM from the mgcv package) that yields predictions that lie above the minimal values.</p>
<p>The problem is how to specify the model. The fo... | 71,107 |
<p>In econometrics, what is meant by reduced form? Also, what are people looking for when they say "I would like to see the reduced form estimates." This has been thrown around at work and individual explanations and Google searches are overly technical. Hoping someone where would be able to give a simple example.</p> | 71,108 |
<p>I wish to compare two regression methods, which has been run 20 times and each time both methods are given the same input (paired). For example I might observe the errors:</p>
<blockquote>
<p>Method A: 1.2 0.9 1.3 1.5 1.2 </p>
<p>Method B: 1.3 1.1 1.4 1.5 1.1</p>
</blockquote>
<p>How do I test which method ... | 71,109 |
<p>I have a vector which contains several values e.g.</p>
<pre><code>a <- runif(8760)
</code></pre>
<p>I wish to perform continuous wavelet transform to the data but the data is required or preferred to be normally distributed. Can anyone provide any information regarding how I could transform the data to be norma... | 43,140 |
<p>In the Multiplicative Error Model (MEM) specification by Engle in "New Frontiers for ARCH models", he wrote that MEM specified an error that is multipled times the mean and the specification is:</p>
<p>$$
x_t = \mu_t \epsilon_t
$$</p>
<p>$$
\epsilon_t | \Im_{t-1} \sim D(1,\phi_t^2)
$$</p>
<p>I am not sure I under... | 45,666 |
<p>I'm new to ML/statistical learning and would like a few pointers in what I need to study to solve my problem. (FTR, I've done an Intro to AI course, classifying Fisher's Iris dataset and things like that).</p>
<p>I'm trying to classify regions or slices in time series data. These are associated with a label. I have... | 32,406 |
<p>I asked people how many times they visited their local pub in a 'normal' week. </p>
<p>The result can be zero, one, two, three, four, and five and more.</p>
<ul>
<li>The mean is 2 and the standard deviation is 1.3. </li>
<li>So two standard deviations above the mean is 4.6. </li>
<li>However, two standard deviatio... | 32,407 |
<p>Let's say I have a binary variable to explain using "some" logistic regression approach. The set of variables I have at disposal are exhaustive for a given period of time and for a longer period a subset of those data are missing. </p>
<p>I think this is a very common issue and was looking for some references about... | 71,110 |
<p>My aim is denoising of the smooth functions based on second generationwavelets.In (unbalanced haar technique for nonparametric function estimation) signal are denoised using unbalanced haar wavelets.
I coud understand best top-down unbalanced haar decomposition,but it no use for the aim of smooth functions.and it s... | 71,111 |
<p>I have two random variables $(X$ and $Y)$ that are always positive. The assumption I'm making is that their logs follow normal distributions (i.e., $N(\overline{\log(X)},s^2_{\log(X)})$ and $N(\overline{\log(Y)},s^2_{\log(Y)})$) . I'm interested in the difference between them, and therefore I'm assuming that the dif... | 71,112 |
<p>I try to fill the gap of linear regression by following the textbook <strong>Patterns Recognition and Machine Learning by Cristopher M. Bishop</strong>.</p>
<p>It's known that the error function for linear regression is </p>
<p>$E(w)=\frac{1}{2} \sum_{n=1}^{N} {y(x_n,w) - t_n}^2$ (defined on page 5)</p>
<p>where ... | 71,113 |
<p>This is a problem I'm encountering in the context of analyzing a data set comprised of all crime locations in a city over a fixed time interval, although it could potentially arise in other types of point processes. The problem has to do with the fact that crime locations are not observed <em>exactly</em>. They are ... | 37,451 |
<p>I have a large data frame in the following form (I apologize for this formatting):</p>
<pre><code>Site Season T SC pH Chl DO.S DO BGA Tur fDOM Flow Rainfall Solar Rain
300N Winter 14.05 1692.77 7.93 NA 82.26 8.42 NA 9.25 NA NA 0.00 ... | 7,169 |
<p>Member of parliament can vote or can be absent during voting. Let assume:</p>
<p>If, for a given MP, there is a pattern present-absent-present (<code>010</code>) in consecutive voting, this absence is strategic - MP does not want to reveal his preferences.</p>
<p>For each MPs I have a data in the format:</p>
<pre... | 71,114 |
<p>I have 3 log scatter plots that I want to establish smooth maximum and minimum lines. What is the usual mathematical method to do that? (Image and Excel file links below.)</p>
<p>The black lines on the scatter plot images are hand drawn. The third scatter plot is especially tricky and not amenable to a moving avera... | 71,115 |
<p>Suppose that I have a huge data set with high number of dimensions (components).
For computational purposes I would like to take just a sample of this data set and work with it instead of working with the huge data set itself.
Is there a good way or technique to sample a dataset?</p>
<p>I was thinking to choose a s... | 71,116 |
<p>I read this definition of an ARCH(1) model:</p>
<p>$$r_{ŧ}=\sigma_{t|t-1}\epsilon_{t}$$
$$\sigma^{2}_{t|t-1} = \omega + \alpha r_{t-1}^{2}$$</p>
<p>However, when it comes to forecasting the h-step-ahead variance, I don't understand why is defined in this way. This is the h-step-ahead conditional variance:</p>
<p>... | 71,117 |
<p>Suppose I have a multivariate Gaussian such that $p(y)=\mathcal{N}(\mathbf{0},\Sigma)$. What would be a quadratic lower bound, $f(y)$ on on $p(y)$.</p>
<p>i.e. for what values of k and $\Omega$ will $f(y)=-y^T\Omega y+k\le p(y)$ s.t. $p(0)=f(0)=\frac{1}{|2\pi\Sigma|^{1/2}}$</p>
<p>As pointed out below $k=\frac{1}{... | 71,118 |
<p>I am having trouble deriving the standard error of a simple regression estimator by hand. Stata code and output for a toy example using the cars dataset is below.</p>
<p>The basic idea is that I have a binary treatment that interacts with a binary covariate. All observations are independent. I'm probably overlookin... | 71,119 |
<p>I wish to model a binary outcome with controls for several thousand time fixed effects in a panel setting, without a special interest in the actual effect coefficient estimates. In variants of linear least squares regression, I could perform a "within transform": demeaning the explanatory variables and response vari... | 49,861 |
<p>This is a question from an old test, taken completely out of context:</p>
<p>"The customers arrive at a shop according to a Poisson distribution with mean $\lambda$ per hour.
Each customer takes $1/k$ hours of service. What is the expected value and the variance of the service time for customers arriving within an... | 71,120 |
<p>I am using a mixed model to assess the effects of various treatments on bee behavior (e.g., avoidance frequency - total avoidances per total visits; feeding frequency, and mating frequency). Bee individuals is my random factor (n=63 different bees), whereas treatment type, animal density, and air visibility are my ... | 71,121 |
<p>I am using JMP to examine differences in vegetation cover in growth form groups (trees, shrubs, forbs, etc.) before and after three treatments with a control.
My sample size is small (n=5) and most of my distributions are not normally distributed.</p>
<p>For the normal distributions I used ANOVA to analyze the diff... | 38,150 |
<p>I know how to do factor and canonical correlation analysis on raw data in <em>R</em>. But sometimes we only having correlation matrices for the data. I'd like to know any <em>R</em> functions which can take correlation matrices as input for factor and canonical correlation analysis. It is easy to write dedicated fun... | 71,122 |
<p>Suppose I have the conditional probabilities of $B$ given $A$ (both categorical): $$\Pr(B|A).$$ The probabilities are given as a contingency table.</p>
<p>Using these conditional probabilities, I can fudge a $B$ column into a dataset that has only an $A$ column. For each row in the dataset, I choose a value for $B$... | 48,216 |
<p>I am reviewing a paper where the authors compare cancer outcomes (binary) between two groups, one having a small sample size of 200 and the other having over 55,000.</p>
<p>The authors then claim that, due to the imbalance and in order to minimize confounding effects, they matched individuals from the larger group ... | 42,530 |
<p>I'm going to be using a logistic regression model and using SGD to determine the feature weights. Is it OK for me to use a mix of binary and real features, without doing anything like scaling or normalization, and just leave it to SGD to give me a model with weights that will work?</p>
<p>Thanks</p> | 71,123 |
<p>I have been occupied with a fairly simple question regarding ordinary inference procedures where my own, and many others, practice feels slightly uncomfortable. We know that the purpose of ordinary inferential methods is to deal with the situation wehre we don't have full knowledge of the population. The populaton p... | 71,124 |
<p>As the title suggests, suppose I want to enter three blocks of variables --according to a theory that I am testing-- and then on the final step, I want to enter few additional predictors (not from the theory), using Stepwise procedure. Can I do that? Thank you.</p> | 71,125 |
<p>Let's say I want to create a line of best fit to approximate the relationship between years of golf experience, and average golf score. </p>
<p>If I have only 4 data points, my line of best fit will have a lot of noise. Is there an equation I can use to say how good the line of best fit is based on the number of ... | 71,126 |
<p>I am trying to quantify the effect of a future random shocks on my seasonal ARIMA model. If I have understood the theory correctly, the easiest way is to express my seasonal ARIMA model in its "random shock" form, and calculate the corresponding psi weights.</p>
<p>Is there a way to do this in R? There is ARMAtoMA,... | 71,127 |
<p>Say I have two correlations: </p>
<p>Sorry about prior ambiguity: A and B are actually groups of people who responded differently to a single survey (multiple choice) question which had to do with X. </p>
<p>The question was: Rate your ability to pick flowers: below average, normal, above average.</p>
<p>So X = a... | 71,128 |
<p>I have a biased coin; it's going to return either heads or tails at some percentage. If I run a test and get back say 28 heads out of 40 flips, how can i best add error bars to indicate i don't have a lot of samples, and the real results could be higher or lower?</p> | 49,862 |
<p>For most of my time in stats, I have been able to ignore the marginal distribution that is usually present at the denominator of any bayesian posterior distribution. </p>
<p>For example, if we write down $L_x(\theta)\pi(\theta)$ and recognize that this function of $\theta$ looks like a distribution of $\theta$ but ... | 71,129 |
<p>Trying to figure out how <code>JMP</code> calculates its results. Seems the differencing equation does not produce same result as <code>JMP</code>.</p>
<p>$\Delta y_{t} = A_{1}\Delta y_{t-1} + A_{2}\Delta y_{t-2} + C$, where $\Delta y_{t} = y_{t}-y_{t-1}$</p>
<p>Adding $\Delta y_{t}$ back to $y_{t-1}$ does not gi... | 32,432 |
<p>I am conducting multiple experiments on moderately large datasets that run over several weeks. I would like to construct confidence intervals for my estimators which are a mixture of means and ratio estimators. I don't know the distribution of my estimators and I have about 40, so I would prefer to get the confidenc... | 32,433 |
<p>I have 2 campaigns (a control and a test campaign), the data are like this:</p>
<pre><code>Capaign # of launches Revenue/Visits
Control 1 2.35
Test 1 1.97
</code></pre>
<p>I'm trying to do a hypothesis testing on Revenue/Visits metric. But since I don't ... | 6,223 |
<p>I'm having some trouble truly understanding what's going in MATLAB's built-in functions of cross-validation. My goal is to develop a model for binary classification and test its accuracy by using cross-validation. I'm looking at comparing a few different models, but I'll just use k-nearest neighbor classification fo... | 71,130 |
<p>My outcome variable is binomial, and I have 11 independent variables and a time variable. The time variable has different slopes, so I fixed it to <code>time-before</code> and <code>time-after</code>. I used the <code>lme4</code> package (the <code>glmer</code> function). I have a random intercept and two random sl... | 574 |
<p>I have a problem concerning non-independence of data in an experimental economic game. Participants are in groups of three and interact with each of the other two. Each interaction between persons A and B is characterised by two variables, how generous A is to B and how much A reports liking B (and the same for B to... | 71,131 |
<p>I am using the usual estimator for kurtosis, $\hat{K}=\frac{\hat{\mu}_4}{\hat{\sigma}^4}$, but I notice that even small 'outliers' in my empirical distribution, i.e. small peaks far from the center, affect it tremendously. Is there a kurtosis estimator which is more robust?
Thanks.</p> | 32,435 |
<p>Just starting to play around with Neural Networks for fun after playing with some basic linear regression. I am an English teacher so don't have a math background and trying to read a book on this stuff is way over my head. I thought this would be a better avenue to get some basic questions answered (even though I s... | 36,572 |
<p>I'm reading <a href="http://rads.stackoverflow.com/amzn/click/0199535256" rel="nofollow">this book</a> on concentration inequalities and I'm trying to solve all of the exercises in the book. The following problem is from the book which I couldn't manage to solve. I have also posted it on <a href="http://math.stackex... | 32,436 |
<p>I see a similar constrained regression here:</p>
<p><a href="http://stats.stackexchange.com/questions/12484/constrained-linear-regression-through-a-specified-point">Constrained linear regression through a specified point</a></p>
<p>but my requirement is slightly different. I need the coefficients to add up to 1. S... | 34,073 |
<p>My problem:</p>
<blockquote>
<p>Let $X_1,\dots,X_n \overset{\mathrm{i.i.d}}{\sim} \mathrm{Cauchy}(\theta,1)$ and suppose we want to estimate the location
parameter $\theta$. Find the log-likelihood function of the given
random sample and show that the maximum likelihood (ML) estimator is
solution of an equa... | 71,132 |
<p>I have a relatively simple multivariate response problem that seems to causing me problems with array indexing. I've scraped/rewworked the model program down to the bare essentials and hopefully haven't cut/replaced too much. I hav3 265 total observations, 5 different groups of responses, each with 53 replications.... | 71,133 |
<p>I have a few points in multiple dimensions. I am able to compute similarity between those items (using, say Cosine distance). For example,</p>
<pre><code> dim1 dim2 dim3
point1 100 1 0
point2 50 1 0
point3 100 0 1
point4 20 0 1
point5 50 0 1
point6 100 0 1
point7 ... | 71,134 |
<p>I am kinda new to stats and understand random sampling, however I am just learning PCA and wondering if it is just a more sophisticated form of sampling? In other words if I have a large data set. and take a random sample would I then apply PCA to it? Or just apply PCA to the data set.</p>
<p>Thanks for any help..<... | 71,135 |
<p>I am brushing up on graphical models, and doing the following problem 3.3 from the book PGM by Kophler.</p>
<p>An alarm A can be set off by either Burglary B or earthquake E. Prove that if $P(a^1| b^1, e^1) = P(a^1 | b^0, e^1) = 1$ then $P(b^1| a^1, e^1) = P(b^1)$.</p>
<p>From the result I can only derive the equi... | 71,136 |
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