question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I have time series data which is international monthly tourist arrival to Malaysia (N=264).</p>
<p>My objective is to forecast tourist arrival for 6 months ahead. After analyzing my data pattern, I found that using Box-Jenkins method gives me the best forecasting model.</p>
<p>The question is that, at such prelimi... | g68017 | [
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<p>There are some cases where I would like to correct for multiple comparisons where the null hypotheses vary.</p>
<p>For example, if I am performing a chi-squared test or a fisher's exact test on multiple contingency tables of different sizes, the null hypotheses vary from table to table. Can I still apply the Benjam... | g27840 | [
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<p>Please explain what is the difference between if two variables are <em>linearly dependent</em> or <em>linearly correlated</em>. </p>
<p>I looked up the wikipedia article but didn't get a proper example. Please explain it with example.</p> | g68018 | [
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<p>Is it necessary to create a stable vector autoregressive (VAR) model satisfying all the necessary checks to create it and then and only can we say that Granger causality holds true?</p> | g20166 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/30159/is-it-possible-to-have-a-pair-of-gaussian-random-variables-for-which-the-joint-d">Is it possible to have a pair of Gaussian random variables for which the joint distribution is not Gaussian?</a> </p>
</... | g49459 | [
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<p>I'm quite new to R and I have a following problem:</p>
<p>I have a simple 2-factor linear model:</p>
<pre><code># factor1 has 8 categorical values, factor2 has 6 categories
Rate ~ factor1 + factor2
model1 <- lm(Rate~factor1+factor2, data=myData)
</code></pre>
<p>And want to put constraints SUM of factor1 coef... | g48607 | [
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<p>I have developed two differing methods in MATLAB which aim to analyse a pop song and then automatically create a 30 second audio thumbnail (a preview clip) containing part of the chorus section.</p>
<p>Both methods have varying results:</p>
<ol>
<li>The first method can create a thumbnail for each track, managing ... | g68019 | [
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<p>I have a following stochastic model describing evolution of a process ($Y$) in space and time. Ds and Dt are domain in space (2D with $x$ and $y$ axes) and time (1D with $t$ axis). This model is usually known as <a href="http://www.stat.missouri.edu/~wikle/ISR_hier_env_v2.pdf" rel="nofollow">mixed-effects model</a> ... | g27850 | [
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<p>I am calculating transition probability matrix (TPM) using <code>hmmestimate</code> command of MATALB.
The simple vector <code>a=[ 1 1 1 1 3 3 3 2 1 3]</code> and for this the TPM is</p>
<pre><code>hmmestimate(a,a)
ans =
0.6000 0 0.4000
1.0000 0 0
... | g27854 | [
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<blockquote>
<p>Let $X_1, X_2, X_3$ be three random variable following a normal distribution
$N(6,4)$. What is the probability that the largest
observation exceeds 8? Hint: $Y = \max(X_1, X_2, X_3)$.</p>
</blockquote>
<p>Here is what I tried:</p>
<p>$P(Y\leq y) = P(X_i\leq y)$ for $i=1,2,3$.
Then
$$
P(Y\leq y)... | g68020 | [
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<p>Are the marginal distributions of a multivariate distribution necessarily the corresponding univariate distributions?</p>
<p>For example: </p>
<ul>
<li>Every marginal distribution of a multivariate normal distribution must be a univariate normal distribution.</li>
<li>So it is for the multinomial distribution (whi... | g68021 | [
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<p>For Dirichlet distribution:</p>
<ul>
<li><p>$X := [x_1, \cdots, x_K] \in [0,1]^K$, $x_i \sim {\rm beta}(\alpha_i, \beta_i)$ and $\sum x_i = 1$. Can we say the distribution of $X$ is a Dirichlet distribution? </p></li>
<li><p>If no, will adding $\sum_{i=1}^K \beta_i = (K-1) \sum_{i=1}^K \alpha_i$ work? </p></li>
<l... | g68022 | [
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<p>I have a dataset with outcomes from a Vasicek distribution (see <a href="http://www.risk.net/data/Pay_per_view/risk/technical/2002/1202_loan.pdf" rel="nofollow">this pdf</a>) and some covariates. Re-expressing the Vasicek's pdf into the exponential family form requires me to transform my data, i.e. instead of $y.\th... | g68023 | [
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<p>First, I'm sorry for the long post, but I needed a second opinion from you, the experts, about this problem! </p>
<p>I was reading a paper by <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1467-9639.2006.00244.x/abstract" rel="nofollow">Gallagher (2006)</a>, where he puts an example on "how one may correctly... | g27858 | [
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<p>In a multiple regression with 16k cases 2 IV (non-normally distributed) and one dependent variable that is also not normally distributed. DV see below:</p>
<p><img src="http://i.stack.imgur.com/zQ524.png" alt="enter image description here"><img src="http://i.stack.imgur.com/tOYbl.png" alt="enter image description h... | g68024 | [
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<p>It was suggested to me recently that the significance of an interaction term in a glm has to be higher than a main effect. For example, p<0.05 is commonly thought of as significant for a main effect but a two-way interaction has to be higher (p<0.025 or something) and a three-way even higher. However, I can't ... | g68025 | [
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<p>I couldn't find any information in the <a href="http://rapid-i.com/content/view/36/209/" rel="nofollow">documentation</a> of rapidminer. I have a data set with the following attributes:
<code>a,b,c,d,e</code>.
The types are: <code>numerical</code>, <code>binomial</code>, <code>binomial</code>, <code>binomial</code>,... | g27861 | [
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<p>How does standardized mean decomposition differ from the simpler dummy variable regression? How does the average in mean outcomes or interpretation of results attributable to a particular treatment or dummy differ when standard decomposition is used, as opposed to dummy variable regression?</p> | g564 | [
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<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/23068/steps-to-figure-out-a-posterior-distribution-when-it-might-be-simple-enough-to-h">Steps to figure out a posterior distribution when it might be simple enough to have an analytic form?</a> </p>
</blockqu... | g49792 | [
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<p>I've had these two explained multiple times. They continue to cook my brain. Missing Not at Random makes sense to be, and Missing Completely at Random makes sense...it's the Missing at Random that doesn't as much.</p>
<p>What gives rise to data that would be MAR but not MCAR?</p> | g45530 | [
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<p>I have 3 binomial data questions asked over 9 months to over 1000 diabetic patients. I would like to test the hypothesis that each of these 3 (quality of care) questions asked to the patients increased over 9 months. These patients who went into a hospital for a medical reason other than their diabetes were treated ... | g68026 | [
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<p>The question is </p>
<blockquote>
<p>Let $X_1,...,X_n$ be drawn iid from $Beta(0.1,0.5)$. Let $\bar{X} = \frac{1}{n}\sum^n_{i=1} X_i$.</p>
<p>a) Derive $\mathbb{E}(\bar{X})$ and $\mathbb{V}(\bar{X})$</p>
</blockquote>
<p>I know how to get the expectation and variance of a random variable from a given distri... | g68027 | [
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<p>Am I right in thinking that it is the average of the sum of $n$ different populations means? </p>
<p>Here it is used in the context that confused me. It's the Chebychev WLLN, apparently. </p>
<p>"If $x_i, i = 1, . . ., n$ is a sample of $n$ observations such that $E[x_i] = \mu_i < \infty$ and Var[$x_i] = \sigma... | g27864 | [
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<p>I am new to R (and by extension statistics), and am having a tough time in making sense of this repeated measures ANOVA formula, please bear with me. I think I understand what the formula implies, but am not too sure on its application. </p>
<pre><code>aov.out = aov(Factor1~Factor2*Factor3 + Error(Factor4), data=Da... | g68028 | [
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<p>I was reading about Bayesian Spatial Scan statistics <a href="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDgQFjAA&url=http://books.nips.cc/papers/files/nips18/NIPS2005_0513.pdf&ei=kTyJUbeOLKrP0gHIkIAY&usg=AFQjCNFKJVOWSum-Q2ww68it_1CmFE1Ppg&... | g68029 | [
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<p>To check multivariate normality, which is the best plot - a chi square qq plot for the entire set of variables or as many qqplots as the number of variables?</p> | g68030 | [
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<p><a href="http://papers.nips.cc/paper/1765-learning-informative-statistics-a-nonparametnic-approach.pdf" rel="nofollow">Learning
Informative
Statistics:
A
Nonparametric
Approach </a> paper presents an approach to parameter estimation by entropy minimization. There are other related works "Minimum-entropy estimation i... | g27867 | [
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<p>Question migrated form <a href="http://stackoverflow.com/questions/10019576/confidence-interval-scoring-with-programming-languages#comment12812602_10019576">http://stackoverflow.com/questions/10019576/confidence-interval-scoring-with-programming-languages#comment12812602_10019576</a></p>
<p>I used a CI scoring algo... | g68031 | [
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<p>how can I test for multivariate normality with kolmogorov-smirnov test and $\chi^2$ test in R program? </p> | g68032 | [
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<p>I want to weight errors differently based on domain knowledge by introducing a cost function. I am trying to solve a regression problem with neural networks and the delta error (<code>predicted output - actual output</code>) is multiplied by the cost weight depending on custom defined cost function. </p>
<p>For a c... | g27871 | [
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0.... |
<p>I have run a linear regression with five independent variables and two dependent variable I am using EPS and ROE as my dependent variable and Board meeting, Board size, leadership, Independend Non-Executive, Audit committee as my Independent variable and my resulting Model is shown as:</p>
<pre><code>Model Summary ... | g27873 | [
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0.002428874373435974,
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0.007300493307411671,
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0.01316000521183014,
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0.01... |
<p>The experiment has $N$ observations $N_i$ which are Poisson Distributed random variables (i.e. we have histogram with $N$ bins. The width of bins is not fixed so I can adjust it ) . I have two hypothesis.The null hypothesis predicts $\lambda_i^{null}$ values of corresponding parameters of Poisson Distribution, alte... | g68033 | [
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<p>When we build a classifier, like SVM or Naive Bayesian, are there any generic rules or theoretical derivations on the size of training data set? For example, to train a SVM-based classifier, what should be the minimum size of training data in terms of feature space and some target performance metrics, such as precis... | g68034 | [
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<p>experts,</p>
<p>I would like to ask for advice regarding the analysis of a dataset I am currently working on. </p>
<p>In the experiment subjects were tested in a reaction time task (RT as dependent variable). In random order every subject was tested in two treatment conditions (factor 'A': placebo vs. drug). Also ... | g16180 | [
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<p>I have a random variable $X$ and I need to calculate the coefficient of variation ($\text{CV}$) of the product of a constant, $c$, and $X$. In other words $\text{CV}(X \cdot c)$. To do this I can apply the following:</p>
<p>\begin{align}
\text{CV}(X \cdot c) &= \frac{\text{sd}(X \cdot c)}{E(X \cdot c)}\\[1em]... | g68035 | [
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<p>I am constructing a predictive model for a binary outcome, which gives me results in a "probability-prediction" fashion such as "0.3-YES" or "0.4-NO". The model is working perfectly. </p>
<p>My question here is what would be the probability that I should trust? is any value below 0.35 or above 0.65 confident enoug... | g68036 | [
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<p>Suppose I have an urn with an infinite number of balls which can be either red or white. I do not know what the proportion of each colour is, but I <em>do</em> know it's a fixed proportion. After drawing $N$ balls, I have observed $r$ red ones and $w$ white ones.</p>
<p>I believe the probability that I will observe... | g68037 | [
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<p>Explain in clear way why in a mixed design the presence of an interaction between a random and a fixed factor inflates the estimate of the main effect of the fixed factor.</p> | g68038 | [
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<p>Say you have survival data like this:</p>
<pre><code>obs <- data.frame(
time = c(floor(runif(100) * 30), floor((runif(100)^2) * 30)),
status = c(rbinom(100, 1, 0.2), rbinom(100, 1, 0.7)),
group = gl(2,100)
)
</code></pre>
<p>To perform a standard log rank test, one can use</p>
<pre><code>survdiff(Surv(... | g27878 | [
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... |
<p>Does anyone know how we can robustly standardize the residuals in MM regression?
First we perform MM regression and then obtain the residuals: how can we robustly standardize the residuals obtained from MM regression? I have found the method for least median squares (LMS) and least trimmed mean squares (LTS) in whic... | g27880 | [
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<p><strong>The background</strong>: I'm analysing survival data using a Poisson model. I've splitted the data on 2 time-scales (attained age and calendar year). Attained age is modelled using flexible parametric functions, calendar year is a categorical variable and I've also included the interaction terms between atta... | g48644 | [
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... |
<p>Given a continuous random variable $X$, what are the units of the PDF and CDF of $X$?</p> | g16195 | [
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<p>I know everybody uses logistic regression as the starting point, but I'm curious to know: What are the other commonly used predictive models when data is primarily binary?</p> | g68039 | [
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<p>In order to determine the right time lag for the Granger causality test, I applied a cross correlation function (CCF) among EU and National legislation and the CCF figure is attached.
I would be grateful if you could kindly help me in resolving the following concerns:</p>
<ul>
<li>I am wondering what time-lag you r... | g27883 | [
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<p>I have posted an almost similar question last week but I want to get some more of the theoretical background <a href="http://stats.stackexchange.com/questions/66145/difference-in-variance-of-factor-scores-for-supplementary-and-active-observation">Difference in Variance of factor scores for supplementary and active o... | g68040 | [
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<p>I generated a BBN below based on environmental variables and a response of some organism. </p>
<p><img src="http://i.stack.imgur.com/GpZh6.png" alt="BBN"></p>
<p>My aim here is to see how environmental variables (A-H in a graph above) interact with each other and influence organisms (phenotypic response). The sens... | g68041 | [
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0.01214... |
<p>My question is about the <strong>reliability of the survey data</strong> (survey answers).
Do you know any statistical methods for that purpose ?
Maybe there are methods which use the data of the demographic questions to test the reliability !?</p>
<p><em>Let's say that a survey is reliable, if I administer it many... | g68042 | [
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<p>I'm trying to verify that my dice are reasonably fair and balanced. I'm not sure I'm doing it right, though, since I'm basically teaching myself stats without references. To achieve this, I've settled on the chi-squared test. Here's what I'm doing:</p>
<p>I have a sample size $N$ of rolls. On a dC, where $C$ is the... | g39974 | [
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<p>Consider a continuous response $Y$ and design matrix vector $\mathbf{X}$. These are related through some function $f(X) = Y$. Suppose that I am interested in estimating the probability that $Y \leq 0.1$ conditional on observing $\mathbf{X}$. </p>
<p>I want to use quantile regression to do this - <strong>can I confi... | g68043 | [
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<p>I have two groups of correlations and I need to test if there's a significant difference between these two groups. Each group consists of correlations between two different variables. I transformed each Pearson r to z according to Fisher r-to-z transformation and calculated a mean of correlations per group. But I'm ... | g68044 | [
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<p>Usually we can construct likelihood ratio for testing the Null hypothesis and alternative hypothesis: The likelihood ratio test $ P( l(\beta_{1}) / l(\beta_{2}) ) < \alpha $ is the rejecting region for the null hypothesis. Then the inequality would reduce to a formula with sufficient statistics as the variable.<... | g35866 | [
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<p>Let's say I wish to test the effectiveness of a new technique of teaching as opposed to an old one. Why is it recommended to have a control group running the experiment in parallel with the group trying out the new technique (what is that group called :)? What is the loss if these experiments are done non-parallely... | g68045 | [
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<p>I am using <code>ccf</code> to find a correlation between 2 time series. I am getting a plot that looks like that:</p>
<p><img src="http://i.stack.imgur.com/S7f65.png" alt="enter image description here"></p>
<p>Note that I am mainly interested in correlation for the lag=0.
Questions:</p>
<ol>
<li>Do interpret it... | g68046 | [
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0.051867369562387466,
-0.0... |
<p>I'd like to find the min/max boundaries of a sliding window of minimum size that contains a certain fraction of the total number of elements in an array or collection of numbers. </p>
<p>Example: taking integers to make it easier to explain, say the proportion of elements that we're looking for is 50% on this array... | g68047 | [
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<p>I'm working on a classification model which is to be built on slightly imbalanced data (nothing extreme, about 60-to-40). Now, I thought to use random forest for this and get some discouraging results (which is not related to this question). </p>
<p>Something I just realized is that all I really need for my particu... | g68048 | [
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<p>The (unbiased) sample covariance matrix</p>
<p>$$\mathbf{S}=\dfrac{1}{n-1}\sum_{j=1}^{n}(\mathbf{X}_{j}-\bar{\mathbf{X}})(\mathbf{X}_{j}-\bar{\mathbf{X}})^{T}$$
can be rewritten as</p>
<p>$$\mathbf{S}=\dfrac{1}{n-1}\mathbf{X}^{T}\mathbf{X}-\dfrac{1}{n(n-1)}\mathbf{X}^{T}\mathbf{1}\mathbf{1}^{T}\mathbf{X}$$</p>
<p... | g68049 | [
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... |
<p>"What is the difference between "significance" and "contribution" of individual variable to a outcome variable? </p>
<p>How to address this while creating a prediction model basically.I understand contribution made by a variable towards the outcome, which shoudl be considered while creating a model but not sure of ... | g68050 | [
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<p>What is the meaning of the term Baseline probability in an experiment? How is it computed, say for a binary classifier? How to measure the performance of a classifier according to a given Baseline probability?</p> | g68051 | [
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<p>I have a probability question for our customer event.</p>
<p>Users choose tickets that contains one word from alphabet {A,E,L,P}. The ticket is not given back and user can choose as many tickets as he wants. There is no maximum number of involved users (but in real there will max. 1000). </p>
<p>In an event we nee... | g68052 | [
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<p>I have a between-group independent variable with two level (A and B) and a dependent variable <em>Y</em> that I transformed in order to normalize the distribution of the residual. I used a Box Cox transformation with the following formula : ((<em>Y</em>^3,169833)-1)/3,169833</p>
<p>With this transformation I observ... | g27891 | [
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<p>I already asked the same question but not got any reply. Please any one help me. I have created term-to-document matrix for document collection. I want to classify them with TMG (Term to matrix generator). For this I have to input labeled term-to-document matrix. I don't know how to created a labeled such matrix. Pl... | g68053 | [
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0.06307961046695709,
-... |
<p>I have seen the review of a multiple regression analysis using time series with a quarterly frequency. The original modeler advanced that the model's residuals were not autocorrelated by disclosing a Durbin Watson score that was reasonably close to 2.0. But, the model reviewer using an autocorrelation analysis mor... | g27893 | [
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<p>Let's say you run a regression with over 200 observations. Would this reasonably large sample mitigate the impact of residuals heteroskedasticity as an offshoot of the Central Limit Theorem, or something similar. As a result, the statistical significance of the regression coefficients would not be in question. </... | g68054 | [
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<p>I want to find out whether there was any significant difference in mineral concentration between chemical analysis and values declared on packaging.</p>
<p>After carrying out Shapiro-Wilk tests to assess the normality of the data obtained in the lab, results indicted that data was both parametric and non-parametric... | g68055 | [
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<p>I have run a series of probit regressions for growth variables across 3 environments. I then graphed the resulting curves as probability density functions (3 curves per graph one for each environment). Then I ran likelihood ratio tests to determine whether grouping by environments was a better fit than not grouping.... | g27894 | [
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<p>In table 3.3 (page 63) of the elements of statistical learning book, the intercept terms for Ridge regression, lasso , pcr and PLS differ. </p>
<p>However, according to the theory in the book, these models should all have the same $\hat{\beta_0} = \bar{y}$. How are the intercepts estimated in the table ? </p>
<p>N... | g68056 | [
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0.04885943979024887,
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<p>I am performing a large number of linear regressions (around 2000) through the origin. Each regression is on a different number of points (between 2 and 1000), and I am using robust regression (with the rlm package in R) to estimate the slope of each regression line.</p>
<p>Clearly I should not trust the results of... | g68057 | [
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<p>I have financial data (return) and use the following model:</p>
<p><img src="http://i.stack.imgur.com/iUeit.png" alt="returnmodel"></p>
<p>where $R_t$ is the return at time t, $\mu$ is set to zero, $\sigma$ is the volatility and $\epsilon$ is an innovation process.</p>
<p>The $\sigma^2$ is estimated with a volati... | g68058 | [
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<p>My fellow classmates and I are stuck on a homework problem that is a three part problem to find the UMVUE of a Poisson distribution.</p>
<p>The problem goes like this:</p>
<p>Let X ~ Pois$(\lambda$), and we want to estimate $\theta=e^{-\lambda}$.</p>
<p>a) Find the Rao-Cramer lower bound for an unbiased estimator... | g27896 | [
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0.028807267546653748,
0.0013406185898929834,
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... |
<p>How can I find the derivative of the modified Bessel function of third kind ($K_{\nu}(x)$) with respect to its order ($\nu$)? Specifically, how can I evaluate </p>
<p>\begin{equation}
\frac{\partial K_{\nu}(x)}{\partial \nu}
\end{equation}</p>
<p>in R, where $\nu$ and $x$ are assumed real to be real.</p>
<p>R pa... | g68059 | [
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0.026023222133517265,
0.012880128808319569,
0.0... |
<p>Models of biased coins typically have one parameter $\theta = P(\text{Head} | \theta)$.
One way to estimate $\theta$ from a series of draws is to use a beta prior and compute posterior distribution with binomial likelihood.</p>
<p>In my settings, because of some weird physical process, my coin properties are slowly... | g48664 | [
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0.029476994648575783,
... |
<p>I have two problems I am trying to solve. I am using MPLUS, but I have very general questions for which MPLUS knowledge will not be necessary.
Terminology: y = DV, x = IV</p>
<p><strong>(1) Simple regression (N=1300)</strong></p>
<p>I want to compare two linear regressions.
In the first model, a metric DV is predi... | g48666 | [
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0.06109367683529854,
0.02... |
<pre><code>x <- read.table('file_name',header=TRUE, row.names=1)
y <- t(x)
y <- data.frame(y)
row.names(y) <- names(x)
names(y) <- row.names(x)
library(corrplot)
corr <- cor(y)
par(ask = TRUE)
corrplot(corr, order = "hclust")
</code></pre>
<p>I'm trying use corrplot on my dataset. The original datas... | g27900 | [
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0.04308757185935974,
0.008462407626211643,
-0.017712010070681572,
0.0018984979251399636,
-0.... |
<p>I have a hard time figuring out if I can use Arellano-Bond GMM when I hahve 3 time periods. In the first period there is 37 observations, 47 in the second period and 60 in the thrid period.
However, the way I understand it, to run the GMM Arrelano-Bond it requires 4 time periods?
I tríed to run it with two lags in... | g68060 | [
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0.03200402483344078,
0.03137843310832977,
0.06093469634652138,
0.017869355157017708,
-0.02009707... |
<p>...2 to 5 questions answered correctly, out of 20 of them? Each question has 5 choices. Probability of getting one right is 1/5. Probability of getting exactly 1 right is ${20 \choose 1} p^1 q^{19}$, with $p=P(\mathrm{right})$ and $q=P(\mathrm{wrong})$ (which I managed to understand and calculate). However how do ... | g49874 | [
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0.029128622263669968,
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0.012927474454045296,
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0... |
<p>I have a Self-Organizing Map and I would like to compute something like its accuracy, precision and specificity to evaluate the performance of my classifier in prediction. </p>
<p>About accuracy, I used two indices: Adjusted Random Index and Adjusted Mutual Information. Are they good choices? How can I also compute... | g68061 | [
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0.03628648445010185,
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0.05850102752447128,
0.1038985624909401,
0.009440... |
<p>I know that some of the questions I am asking here have been answered in a general case in the two questions I am referring to in the problem section. Nonetheless, I am asking for a very specific case here. --> The representation of a high-dimensional data set by a low number of data points</p>
<p><strong>Backgroun... | g68062 | [
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0.009977808222174644,
0.015761205926537514,
0.05220538377761841,
0.01... |
<blockquote>
<p>If the dependent variable is normally distributed for a fixed set of predictor values, then the residual values should be normally distributed with a mean of 0.</p>
</blockquote>
<p>I have two questions based on the above paragraph:</p>
<p>First, I don't understand why the above paragraph must be tr... | g68063 | [
0.04064743593335152,
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0.005178346298635006,
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0.035040345042943954,
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-0.0... |
<p>This is a mockup of a dataset I am currently working on:</p>
<pre><code>> df <- data.frame(name = LETTERS[1:3],
trials = c(40, 60, 60),
successes = c(22, 30, 45))
> df$success.rate = df$successes / df$trials
> df
name trials successes success.rate
1 A ... | g68064 | [
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0.00395490787923336,
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0.022... |
<p>Just a little thought I've been having. If we rolled a fair dice 60 times, and got 60 sixes in a row, we would (wrongly?) definitely assume that something fishy's going on. Is there any statistical measure which could raise our attention to this potential problem? Or is it simply not a problem, since this sequence i... | g68065 | [
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0.009730985388159752,
0.056875769048929214,
0.0632091760635376,
0.0090... |
<p>First of all, I apologize since this question has probably been asked many times and is easily answered. However, as a statistics amateur I simply couldn't figure out what keywords are relevant to my question.</p>
<p>Suppose you have 100 merchants and 100 products. Each merchant sells a certain range of products, r... | g68066 | [
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<p>I want to predict an event based on transactional data. I'm only interested in predicting either future hazard or time-to-event. My understanding is that to predict in the future I have to use a fully-parameterized proportional hazard model with time-varying covariates. By "fully parameterized" I mean that I assume ... | g48675 | [
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0.014860466122627258,
0.0005062574637122452,
0.028241559863090515,
0.0413961261510849,
0.01879... |
<p>I'm trying to understand how the <code>margins</code> and <code>marginsplot</code> work after <code>stcox</code> command in Stata.</p>
<p>So let's start with a dumb example: </p>
<pre><code>webuse stan3
stset
stcox i.posttran i.surg
</code></pre>
<p>That gives me result</p>
<pre><code>---------------------------... | g68067 | [
0.03324756771326065,
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0.01193560753017664,
0.018371790647506714,
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0.0944129005074501,
0.037787746638059616,
-0.02951585315167904,
-0.04306921735405922,
-0.002729484811425209,
0.07215820252895355,
0.0656244307756424,
-0.022913... |
<p>I have a variable (VAR1 )with two possibilities, let's call them V and N.</p>
<p>I asked my experiment participants to detect the VAR1 value.</p>
<p>My aim is to compare the correctness rate of answers by participants (e.g. when the value of VAR1 is V, the participants can answer V or N, but V is correct, so if 70... | g48676 | [
0.04235561192035675,
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0.017742536962032318,
0.004794557578861713,
0.0072193690575659275,
0.01684698462486267,
0.05448882654309273,
0.038018833845853806,
-0.0030419048853218555,
0.0182... |
<p>One of the predictors I had in a logit model is "City". Problem is this categorical variable has too many factor levels. e.g. In a Sample of $\sim 3000$ there are already $\sim 200$ different cities. </p>
<p>Is it fair to still retain City as a predictor or should I purge it entirely from the model? An alternative... | g68068 | [
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0.... |
<p>If I want to make a causal statement based on selection on observables. One typically assumes "Common Support" (/"Overlap") - which means that for any value of the confounding variables X a unit i can be potentially observed with treatment (D=1) and without treatment (D=0).
I.e.: </p>
<pre><code>0<P(D=1|X=x)<... | g68069 | [
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-0.03307536244392395,
0.008772449567914009,
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0.022842690348625183,
0.037876028567552567,
0.036915961652994156,
0.015169749036431313,
-0.031815916299819946,
0.007052104454487562,
-0.030269576236605644,
-0.02853097766637802,
0... |
<p>I want to conduct a simple propensity score estimation where the treatment $D_i$ is a binary variable ($D_i=1$ individual $i$ participates in the labor market program, zero otherwise). I estimate the propensity score using a simple probit model using various explanatory variables (including gender). </p>
<p>Then I ... | g68070 | [
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0.006159953307360411,
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0.02412811852991581,
0.07041556388139725,
... |
<p>In large companies with thousands of employees, how to get the number of employees per month? everyday there could be new employees, resigned or terminated employees, etc. If I want to get the number of the employees in a given month it will be confusing since the number of employees differs from one day to another ... | g68071 | [
0.00714499969035387,
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0.010174923576414585,
0.004505493678152561,
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0.06233182176947594,
0.04469739645719528,
0.0008500809199176729,
-0.025781970471143723,
0.014481084421277046,
-0.023510923609137535,
0.047568429261446,
0.0305... |
<p>I have three different histograms which are generated from one sample. In each of the histograms, both variables are the same. Although binwidths for each histogram is different. By looking at each of them, we can have different interpretation of the data that made these histogram. One of them shows a bimodal distri... | g49793 | [
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0.023155955597758293,
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-0.004512346815317869,
0.02772335708141327,
0.01112570334225893,
0.01814679242670536,
0.035... |
<p>If I understand correctly, a Linear Discriminant Analysis (LDA) assumes normal distributed data, independent features, and identical covariances for every class for the optimality criterion.</p>
<p>Since the mean and variance is estimated from the training data, isn't it already
a violation? </p>
<p>I found a quo... | g68072 | [
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0.010015949606895447,
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0.037172917276620865,
0.019668368622660637,
0.019780421629548073,
0.0... |
<p>Thanks in advance. I have four I(1) variables I'm trying to model by VAR/VEC. I know that it is only okay to model non-stationary variables in levels only if they are cointegrated. What I would clarification on is if they ALL have to be cointegrated with each other or is it sufficient that there only needs to be ... | g68073 | [
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0.07592426240444183,
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0... |
<p>Let $X_1,X_2,\dots ,X_n$ be a random sample from a distribution with pdf $f(x,\theta)$. Find a level $\alpha$ most powerful test of $H:\theta=\theta_0$ against $K:\theta = \theta_1$ when
$$f(x,\theta)=\theta x^2I_{(\theta, \infty)}(x),\theta_0 \neq \theta_1$$</p>
<p>I consider $$\frac{p_1(x)}{p_0(x)}=\dfrac{\theta... | g27916 | [
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-0.005354860797524452,
-0.03062727488577366,
0.006246533244848251,
-0.012928087264299393,
-0.01988317258656025,
0.03298671171069145,
-0.01758885756134987,
0.04398505017161369,
0.04046220704913139,
0.00583428330719471,
-0.02510036714375019,
0.007... |
<p>I'm doing this problem:</p>
<pre><code>A student is applying to Harvard and Dartmouth. He estimates that he has
a probability of .5 of being accepted at Dartmouth and .3 of being accepted
at Harvard. He further estimates the probability that he will be accepted by
both is .2. What is the probability that he is acce... | g68074 | [
-0.00806729681789875,
0.03605503588914871,
0.008928852155804634,
-0.03818061947822571,
-0.006035713478922844,
0.004473596345633268,
0.012380285188555717,
0.073494553565979,
-0.06403949111700058,
-0.026828555390238762,
-0.07876057922840118,
0.040237490087747574,
0.029632236808538437,
0.0394... |
<p>Can I run a Wilcoxon matched pair signed rank test after using Coarsened Exact Matching to match data? If yes, please guide me through the process. I use STATA. </p> | g205 | [
0.016792720183730125,
-0.06084047630429268,
0.010082267224788666,
-0.03962625190615654,
0.00844157300889492,
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-0.05664730444550514,
-0.025113537907600403,
0.04064735025167465,
-0.006419900804758072,
-0.019... |
<p>Suppose $$E[y|\textbf{x}] = \beta_0+\beta_{1}x_{1}+\beta_{2}x_{1}^{2}+\beta_{3}x_{3}$$</p>
<p>Is there an easy interpretation of the coefficients? If there was no $\beta_{3}x_{3}$ term then we would have a quadratic and take the derivative to get an interpretation. So maybe we want take the partial derivative with ... | g68075 | [
0.0013368396321311593,
0.011583968997001648,
-0.015095628798007965,
-0.007291139103472233,
0.0746830478310585,
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-0.01601225882768631,
-0.05458446219563484,
0.016151640564203262,
0.000722785945981741,
-... |
<p>I need to confirm a stats question and I was wondering if you could
let me know whether you would agree with my thought process:</p>
<p>would need this good enough for publication purposes in a Psychology journal, for what reason I am a little unsure:</p>
<p>Essentially: How do I get a variation measure of z-score... | g27918 | [
-0.04171766713261604,
-0.029822327196598053,
-0.004858043044805527,
-0.039616432040929794,
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0.020653795450925827,
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0.027738936245441437,
0.030675075948238373,
0.011617586947977543,
-0.002788473619148135,
... |
<p>In a project that I am doing to evaluate customer behaviour, I have asked a set of questions such as whether they read the unit pricing before they decide to purchase a particular product or do they only buy a particular product if it is on 'special'.</p>
<p>In a population of 60 stores (with unequal customer base ... | g68076 | [
0.012886438518762589,
0.05076035112142563,
0.018559157848358154,
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-0.014407188631594181,
0.06647240370512009,
-0.028697185218334198,
0.02322169952094555,
0.0... |
<p>I have problem on generating correlation matrices using Wishart distribution. I read some articles about Wishart distribution, and it turns out that Wishart distribution is commonly used to generate covariance matrices. Is it possible to generate correlation matrices using Wishart distribution? Any information about... | g68077 | [
-0.003038497641682625,
-0.011364738456904888,
0.008073444478213787,
-0.07106690853834152,
0.020600587129592896,
0.03859606385231018,
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0.025872765108942986,
-0.03009050525724888,
0.03397286310791969,
0.03840775415301323,
-0.027230696752667427,
0.019154733046889305,
0.... |
<p>What are the best methods for building document exemplar training sets for classification of unstructured data (documents and emails) using SVM? How do I optimize F-scores for these models when using Cross-Fold validation?</p> | g68078 | [
-0.017479756847023964,
0.04901350662112236,
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-0.011840459890663624,
0.003923042677342892,
-0.03409213200211525,
0.05974777042865753,
0... |
<p>I wish to know what statistical literature is relevant for the following problem, and maybe even an idea on how to solve it.</p>
<p>Imagine the following problem:</p>
<p>We have 4 possible treatments for some disease. In order to check which treatment is better, we perform a special trial. In the trial, we start... | g68079 | [
0.04326252639293671,
-0.0010568253928795457,
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0.06606288999319077,
0.006823129486292601,
0.006889954674988985,
0.004459911026060581,
0.040334586054086685,
0.05517005920410156,
0.03... |
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