question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am new to ARIMA modeling and currently encountering a weird situation with time series of count data. The time plot shows clear seasonal patterns.ACF also hints on presence of seasonality. However, seasonal unit root test in R shows that series is seasonally stationary. </p>
<p>If I include seasonal differencing ... | g40961 | [
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<p>In practice, we may always be asked to check the skewness and kurtosis of a data set. I have two questions.</p>
<p>Given a probability distribution, how can we determine/evaluate the skewness and kurtosis of this data set?</p>
<p>If we have the data sample itself, which kind of statistics can help us evaluate its ... | g12790 | [
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<p>I'm having difficulty with some syntax in R using the <code>sem</code> package. I'm trying to do the following:</p>
<ol>
<li>Create four latent variables with three (attitudinal) indicators
each</li>
<li>Regress these latent variables on an observed (behavioral)
variable</li>
<li>Compare this to a model where ... | g35790 | [
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<p>I am in the process of empirically developing a questionnaire and I will be using arbitrary numbers in this example to illustrate. For context, I am developing a psychological questionnaire aimed at assessing thought patterns commonly identified in individuals who have anxiety disorders. An item could look like "I <... | g38104 | [
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<p>I'm doing an experiment with moodcongruency (influence of mood on word retrieval). Prior to inducing a mood, the participants will memorize a list of words containing an equal amount of positive, negative or neural words. </p>
<p>Before the actual experiment, I want to make sure that the words are indeed associated... | g57944 | [
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<p>I'm doing a project on measuring customer satisfaction using SERVQUAL. How do you calculate the standard deviation of each statement? </p>
<p>For example, if for one of the questions, there were:</p>
<blockquote>
<ul>
<li>2 respondents as strongly disagree (SD)</li>
<li>5 disagree (D)</li>
<li>20 neutral (... | g57945 | [
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<p>I am learning about evaluating clustering outcome and am confused about the scatter matrices. Hoping to get some help here.</p>
<p>The within-cluster scatter matrix $S_W$is defined as:
$$
S_W=\sum _{ k=1 }^{ K }{ \sum _{ x\in { C }_{ k } }^{ }{ \left( x-{ \mu }_{ k } \right) { \left( x-{ \mu }_{ k } \right) }^... | g12794 | [
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<p>Can I interpret the coefficients in a VAR model in the same way as I do in a normal OLS regression?</p> | g57946 | [
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<p>I have a 12% holdout cross validation and I've done a bunch of repetitions which
gives me a distribution of scores for each method. </p>
<p>I'd like to do some sort of hypothesis testing for comparing methods. Each score I have is unitary value between 0 and 1. A view at a histogram yields an approximately normal ... | g41584 | [
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<p>I am using the <code>caret</code> package to do feature selection with <code>rfe</code> while training a <code>knn</code> classifier. I want to tune both the <code>k</code> parameter and the <code>size</code> of the variable subset by taking the best value of the metric <code>ROC</code> from the <code>twoClassSummar... | g57947 | [
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<p>Following question:
<a href="http://stats.stackexchange.com/questions/47483/interpretation-of-the-regression-coefficient-of-a-proportion-type-independent-va"><a href="http://stats.stackexchange.com/questions/47483/interpretation-of-the-regression-coefficient-of-a-proportion-type-independent-va">Interpretation of th... | g12796 | [
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... |
<p>It is well known that the AIC can be used to compare nested models. </p>
<p>Additionally, I believe I am correct in saying that you can also use the AIC to compare non-nested models on the same dataset (please correct me if I am in fact wrong). However, it is not correct to use the AIC to compare between different ... | g57948 | [
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<p>Using the excellent forecast package by Rob Hyndman, I came across the need to not only have prediction intervals, but to simulate a number of future paths, given past observations of a time series with complex seasonalities.
There is something for less complex time series with one or two seasonalities only (simulat... | g57949 | [
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0.000... |
<p>I'm working on a model of saving account amounts. It shows a seasonality: On the 1st day of every month the amount always decreases.</p>
<p>This is reasonable as people probably need draw money to pay rental or other everyday bills.</p>
<p>However, before seasonality adjustment is applied, I'm wondering: Is there ... | g57950 | [
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<p>I am a senior doing a science fair project on the efficiency of fuels. For each fuel I tested, I have a time series of temperature.
I want to plot these into an excel xy chart, how do I plot them if the constants (time) are not the same for each set of data?</p> | g12799 | [
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<p>The recent events in Japan have made me think about the following.</p>
<p>Nuclear Plants are usually designed to limit risk of serious accidents
to a 'design basis probability' for example, say, 10E-6/year.
This is the criteria for a single plant.
However, when there is a population of hundreds of reactors, how do ... | g57951 | [
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<p>I would like to rank categorical features by the order or importance in a classification/regression setting. </p>
<p><strong>Input</strong></p>
<p>There are two features, which are survey questions:</p>
<ol>
<li>"how is your mood?": four possible answers are crappy, mediocre, good and great!</li>
<li>"are you hap... | g1013 | [
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0.0... |
<p>Does $R^2 * \mbox{slope}$ provide an estimation of cause and effect? For example, if $R^2$ of miles driven and coffee consumed is $x\%$ and the slope of the coffee-and-miles dataset is $y$ (miles/coffee), can you say "$z$ of each cup of coffee drunk is related to the number of miles driven"?</p> | g12802 | [
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<p>A. Mulitivariate normal distribution case with latent variable $X$</p>
<p>Mapping from the low-dimensional space $X$ in Q-dimensional space (Q=2) to the high-dimensional space of $Y$ in D-dimensional space (say D=10) can be considered as</p>
<p>$$Y=WX+\mu+\epsilon$$</p>
<p>Distribution of $Y$ given $X$ taking iso... | g57952 | [
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<p>I was thinking that in a very standard case such as a simple linear model with iid errors and no endogeneity, I would get the same results using the a simple least square estimate (such as provided by <code>lm()</code> in R) and a simple GMM estimator with an identity matrix as the weighting matrix and the matrix of... | g57953 | [
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<p>I have two sets of data:</p>
<pre><code>> dput(a)
c(15984.24, 17359.7, 17341.47, 18461.18, 24924.5, 46039.49, 41595.55,
19403.54, 21827.9, 21043.39, 22136.64, 26229.21, 57258.43, 42960.91,
17596.96, 16145.35, 16555.11, 17413.94, 18926.74, 14773.04)
> dput(b)
c(1.16776468870609, 1.25440938833205, 1.375973704... | g57954 | [
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<p>I recently was asked to help characterize some surfaces (raised ink dots on paper) that were scanned with a profilometer, yielding height data across a grid of x & y coordinates. The critical question was to characterize the average dot height. The data were rather noisy as the paper was not perfectly flat, so I... | g57955 | [
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<p>Imagine that I have goal scoring data for a hockey team. They average 2.43 goals scored per game with a standard deviation of 1.63 for this data set. They have played 82 games.</p>
<p>I have two subsets of this data set; each subset represents data for the team when a specific goalie is on the ice (Goalie A and Goa... | g57956 | [
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<p>I would really appreciate if you could help me with your expertise:</p>
<p>I have a study in which I evaluate patients for healing after discharge. So I have two group, healed and non-healed patients. </p>
<p>The question I want to ask is how to analyze independent predictors of healing (or non healing) within a d... | g12807 | [
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<p>I am a beginner in this area so please bear with me. I have 2 data sets:</p>
<ol>
<li>information about the cars which were sold in
particular area (cost, model, number of seats, manufacturer, etc.)</li>
<li>information about social status of people in particular
area (occupation position, average salary, education... | g57957 | [
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<p>I have weekly sales figures, and would like to convert them into daily sales figures, making a simple hypothesis that there are 7 days with equal sales "power".</p>
<p>Let's imagine that I have:</p>
<pre><code>Week, Sales
1,11
2,15
3,9
</code></pre>
<p>Now I can easily convert this into daily figures with "flat" ... | g57958 | [
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<p>Let's say that I want to compute the effect size of a certain intervention, for which I have both the raw data and some statistical value that can be transformed to an effect size. For example, if one has the t score and the df value of a t-test, one can transform it into Cohen's d by using the equation</p>
<p>$$d=... | g12811 | [
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<p>Suppose I have a few time series, that are strongly correlated to each other, and I consider this to be noisy data. How do I use the pseudoinverse technique from image processing to filter this data?</p> | g57959 | [
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<p>I'm running Gauss Seidel value iteration on a weapon-target assignment problem (I can explain this more later if necessary, but i don't think it is). My VI is converging <em>exactly</em> in 2 iterations. I'm not sure if it is because my problem has ~1/2 absorbing states (i.e. if you expend all the weapons or if yo... | g57960 | [
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<p>I have a data set of 350 points, I want to estimate the lag 1 auto correlation for different sub-sets of the data.</p>
<p>More precisely I want to take non overlapping windows of length 1,2,3....n and calculate the auto correlations of these sub-sets. So for n equal to 2 I take every second observation similarly fo... | g57961 | [
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<p>I was writing with a question regarding a time-varying state space model of the form:
\begin{align}
y(t) &= \mu_1(t) + A(t)x(t) + v(t); &v(t) &\sim (0, R(t)) \\
x(t) &= \mu_2(t) + \Phi(t)\!\times\!x(t-1) + s(t); &s(t) &\sim (0, Q(t))
\end{align}
$x(t)$ is of the form: $x(t) = \log[1-... | g12813 | [
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<p>I have data for 110 companies re. the price they have paid for a service annually between 2004 and 2011. Now I would like to find out if there is a statistically significant difference between the price they are charged pre and post 2008 . . . how should I deal with this, given that I have 8 observations per company... | g57962 | [
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<p>I like to keep analyses all in SAS or all in R when I can help it and lately have been using R more and more, but there's one analysis that I do somewhat routinely that has given me trouble in R.</p>
<p>I have repeated measures data where I would like to fit the following model: $$Delta = Day + Group + Day\times Gr... | g15043 | [
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<p>This might sound dumb but if I have $d_i$, where $i=1 \dots n$ observations and I assume they are exponentially distributed, before I use the MLE, should I transform my data to follow an exponential distribution? The reason I ask is because I often see others who normalize their dataset prior to the MLE if they ass... | g57963 | [
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<p>I have a dataset with a lot of missing values and mix of continues and categorical variables. I want to use something like group lasso to do features selection. Probably the output is binary 0,1 and so grouped lasso logistic regression seems to be the more sensible choice. </p>
<p>My problem is the very large numb... | g57964 | [
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<p>Can anyone give some advice on solving the following problem?</p>
<p>$X$ is distributed as $N(\mu_1, \sigma_1^2)$;</p>
<p>$Y \big| X > c$ is distributed as $N(\mu_2, \sigma_2^2)$;</p>
<p>$Z \big|\min(X, Y) >c$ is distributed as $N(g(X,Y), \sigma_3^2)$.</p>
<p>Here $\mu_1$, $\sigma_1$, $\mu_2$, $\sigma_2$, ... | g57965 | [
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<p>I’m not very familiar with when and why you would stratify on a variable or set of variables in a regression analysis generally and would like to know what the issues are particularly in contrast to including the variable (by itself or as an interaction term) in the model without stratifying. </p>
<p>I’m somewhat ... | g37708 | [
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<p>Using the normal distribution. Let $X \sim N(1, 2)$ and $Y \sim N(2, 3)$ where $N(\mu, \sigma^2)$ denotes the normal distribution with mean $\mu$ and variance $\sigma^2$. $X$ and $Y$ are independent.</p>
<p>What is $P(X>Y)$?</p>
<p>I know that $P(X>Y)$ can be translated to mean $P(X-Y>0)$ and I want to ma... | g49794 | [
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<p>Say, for example, that we have a logistic regression model which outputs the probability that a patient will develop a particular disease based on many covariates. </p>
<p>We can get an idea of the magnitude and direction of the effect of each covariate in general by examining the coefficients of the model and cons... | g48462 | [
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<p>What is the correct way to test for significant differences in parameter estimates in the following case:</p>
<p>I have a dependent variable (height for age) and a independent variable (household state pension benefits). These are observed in two years.</p>
<p>To see if there is an endogeneity problem I want to in... | g41595 | [
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<p>I have an experimental value and I want to find out which of the theoretical values are 'significantly' close to the experimental value.</p>
<p>Say for example my experimental value is:</p>
<pre><code>3000
</code></pre>
<p>and my theoretical values are:</p>
<pre><code>2500,3005,3300,2750,2900,3100,2995,3000,3010... | g57966 | [
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<p>I applied Box-Cox on a regression model with heteroscedasticity. Although the transformed model looked better than the original, it still showed signs of heteroscedasticity. What else can I do after Box-Cox to almost eliminate heteroscedasticity? The original model showed a skewness (regarding normality) of 1.4 wher... | g27263 | [
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<p>I would like to study the impact the advertising of a product on its sales (weekly data for 5 years).
As the final aim is to forecast what would be the impact on sales of a change in the advertising presence in the media, I was considering including also other variables (such as competitors prices, macroeconomics va... | g57967 | [
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<p>I have a dataset of samples belonging to >100 classes. I want to classify and/or cluster these classes. I have the following questions:</p>
<p>1) Is one classifier efficient for such problem? or one classifier for each one/subset of classes? (From my point of view: the efficient solution is to discover the features... | g57968 | [
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<p>If I were to define the coordinates $(X_{1},Y_{1})$ and $(X_{2},Y_{2})$ where </p>
<p>$$X_{1},X_{2} \sim \text{Unif}(0,30)\text{ and }Y_{1},Y_{2} \sim \text{Unif}(0,40).$$</p>
<p>How would I find the expected value of the distance between them?<br><br>
I was thinking, since the distance is calculated by $\sqrt{(X_... | g12820 | [
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... |
<p>Hello how to show the following:</p>
<p>Observations $(X_1,X_2,..,X_n,)$ are i.i.d. over $[0,2\pi)$ with density
$f(x,\theta) = \exp[\theta_1\cos x + \theta_2 \sin x -c(\theta)]$ where
$\theta =(\theta_1,\theta_2) \in R^2$</p>
<p>Find an expression for the Fisher information $I(\theta)$ involving integrals and s... | g49519 | [
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0.06037191301584244,
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0.0... |
<p>I am generally curious what the term "principled" means. </p>
<p>It was used in the title of an unpublished manuscript, "Combining Computer Models in a Principled Bayesian Analysis". In addition, Zhang 2004 says "There are several advantages to a principled Bayesian analysis" here:</p>
<p><img src="http://i.stack.... | g57969 | [
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0... |
<p>I am new to Stats and came across this problem while running my analyses on SPSS which I cannot explain. </p>
<p>How is it that even after transforming my data by logging it, it still has the same p-value as the raw data set that was not transformed?</p>
<p>Sorry for sounding really ignorant here!
Thank you in adv... | g57970 | [
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<p>Is there a way to correlate data regardless of distribution? I know the Choleksy transformation is used for normally distributed data, but is there a general method that applies to any case?</p>
<p>To include more information: </p>
<ul>
<li>I want to be able to decide any distribution shape for any variable.</li>
... | g57971 | [
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0.... |
<p>Does anyone know of an R equivalent to SAS <code>PROC FREQ</code>? </p>
<p>I am trying to generate summary descriptive statistics for multiple variables at once.</p> | g12826 | [
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<p>I'm trying to get aquainted with robust regression methods and there's something about M-estimators that I don't understand.</p>
<p>In "Robust statistics" (Maronna, Martin, Yohai) it is said that if both our x's and y's are random, the M-estimator of regression is given as a solution to</p>
<p>$$
\sum \rho (\frac{... | g14354 | [
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0.00... |
<p>How to show the following:</p>
<p>Using the student t-distribution with $k > 0$ degrees of freedom, location parameter
$l$ and scale parameter $s$ having density</p>
<p>$ \frac{\Gamma ((k+1)/2)}{\Gamma ((k/2) \sqrt{k \pi s^2}} \{ 1 + k^{-1}( \frac{x-l}{s} )\}^{-(k+1)/2}$</p>
<p>How to show that $t$-distribut... | g57972 | [
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0.02829836681485176,
0.030132852494716644,
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0.06159636378288269,
0.003... |
<p>I am looking for software packages for working with <strong>exponential random graph models</strong> (fitting/generating them and sampling from the graph distributions).</p>
<p>I have only found two packages so far, both using R: <a href="http://statnet.csde.washington.edu" rel="nofollow">ergm/statnet</a> and <a hr... | g12829 | [
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<h1>Books to Learn Statistics using R</h1>
<h2>What exactly is the book I'm looking for.</h2>
<p>What I am looking for is a book that teaches you statistics while using R to give you hands-on experience and thus end up helping you learn R together. I've seen on amazon many books that attempts to do that, but not with... | g57973 | [
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0.08468995243310928,
0.021456575021147728,
0.06499403715133667,
-0.... |
<p>I've been looking for the internet explanation about the hidden Markov model (HMM) and its implementation but I think there's not quite good explanation. Does anyone know and guide me through this like tutorial and its implementation. There will be feedback and not do this as charity.</p>
<p>So I hope there will be... | g57974 | [
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0.020351801067590714,
0.07646067440509796,
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-0.02261943742632866,
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0.02393580973148346,
0.0306453425437212,
0.0135224... |
<p>There is quite some number of ways how to robustly fit a linear regression model, e.g. using M-estimation based on Tukey's biweight loss or on Huber's loss, see e.g. <a href="http://en.wikipedia.org/wiki/Robust_statistics" rel="nofollow">Wikipedia</a>.</p>
<p>I got two questions about the two mentioned cases:</p>
... | g57975 | [
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0.08660547435283661,
-0.... |
<p>I have a reasonable understanding of why multicollinearity is a problem is regression models, along the <a href="http://stats.stackexchange.com/questions/1149/is-there-an-intuitive-explanation-why-multicollinearity-is-a-problem-in-linear-r">lines</a> of this excellent post.</p>
<p>To summarise my understanding, for... | g57976 | [
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0... |
<p>I am reading <a href="https://webfiles.uci.edu/mdlee/LeeWagenmakers2013_Free.pdf" rel="nofollow">a book example</a> (diagram from p10) in which a person scores 9/10 on which we assumed a uniform prior. The posterior distribution could be easily worked out analytically, but the book gives an example of estimating the... | g57977 | [
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0.013190103694796562,
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0.... |
<p>Suppose that I have two distance matrices for the same set of items.
By a distance matrix I mean a square matrix whose (i,j)th entry holds the distance (in terms of cosine similarity) between ith and jth items. The ith and jth items are the same items in both matrices. Such a situation might happen when we gather in... | g12834 | [
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0.03935365378856659,
... |
<p>First of all, I appreciate lot of creator of this web and any attention on this question.</p>
<p>I asked related question here: <a href="http://stats.stackexchange.com/questions/24752/52-variables-after-backward-variable-selection-on-logistic-regression-on-160-var/24811#24811">52 variables after backward variable s... | g12835 | [
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0.0016488180262967944,
... |
<p>In my Bayesian network there are plenty of repetitive variables leading to the use of plates(<a href="http://en.wikipedia.org/wiki/Plate_notation" rel="nofollow">http://en.wikipedia.org/wiki/Plate_notation</a>). I do not want the exponential space complexity in implementing the bayesian network. But the way traditio... | g2959 | [
-0.024041946977376938,
0.05551942065358162,
0.009591279551386833,
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0.0023489429149776697,
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0.019812270998954773,
0.006216008681803942,
0.036823682487010956,
0.0... |
<p>I have once heard that decision trees can handle dependent features very well, compared to e.g. Naive Bayes classifiers. However, I can't find any scientific source for that.</p>
<p>So my question: is it true and if yes, is there any source?</p> | g57978 | [
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0.07953950017690659,
0.053378... |
<p>I would like to predict BMR or Basal Metabolic Rate (energy expended by the body while awake) using the predictors age, weight, height and gender. Please suggest the interactions that I should be considering here.
I am using spss to do this regression. Shouldn't the significance of interactions between continuous va... | g57979 | [
0.028319083154201508,
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0.0009528789669275284,
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0.04147801920771599,
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0.010905840434134007,
... |
<p>It is admitted that it is complex to interpret main effects when they are involved in an interaction.</p>
<p>Lets take a regular linear model, with two categorical 2 level variables A and B who are interacting together. The model can be written:</p>
<pre><code>lm(Response ~ A + B + A:B)
</code></pre>
<p>Lets call... | g2962 | [
0.009996646083891392,
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0.027483344078063965,
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0.0... |
<p>So,
I understand what sufficient statistics is but I am unable to extend those ideas to minimal statistics, completeness, ancillary and eventually connect it with UMVU estimators?
Can someone explain it to me or point me the (easy to understand) material?
Thanks</p> | g308 | [
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0.012997672893106937,
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<p>Suppose I have a Bayesian inference problem where $E$ is the result of a chemistry experiment. The chemistry experiment consists of a controlled sequential digestion of one end of the protein using a specific enzyme that has known statistical properties. The sequence of the protein is unknown at the beginning of the... | g57980 | [
0.03418411687016487,
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0.007034662179648876,
0.016144607216119766,
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0.03... |
<p>The following is a lemma I read $$\mathbb E(X|X>0)=\frac{\mathbb E(X)}{\mathbb P(X>0)}.$$ Could anyone tell me how to prove it, please? Thank you!</p>
<p><strong>Update</strong></p>
<p>Using the conditional expectation formula I got the following</p>
<p>$$\mathbb E(X|X>0)=\sum_x x\mathbb P(X=x|X>0)=\s... | g12841 | [
0.0271808709949255,
0.008930468931794167,
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0.02510... |
<p>I'm at a beginner level, so please bear with me.</p>
<p>This is a call center use case. For every week, certain number of calls are received. The average is about 20. This seemed like a Poisson distribution to me (rate per interval). I took about 100 data points. I tried to answer the question "what is the probabil... | g196 | [
0.034404512494802475,
0.039130907505750656,
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-... |
<p><img src="http://i.stack.imgur.com/7xQQ3.png" alt="enter image description here"></p>
<p>I am running a fixed effect panel regression with 81 groups x 20 periods, so approx 1620 (unbalanced) observations.</p>
<p>I use the following to create dummies:</p>
<pre><code>*create timedummy
tabulate refper, generate(re... | g12842 | [
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... |
<p>I am going to attempt to give you as much background as possible.<br>
My <strong>independent variable</strong> is nominal and describes the number of days after which an insect was exposed to new conditions (0,1,3,5,7).<br>
The <strong>dependent variable</strong> is the insect's condition after the experimental peri... | g57981 | [
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0.009693443775177002,
0.0552121177315712,
-0.0002... |
<p>The following scenario is given in Dekking's "A Modern Introduction to Probability and Statistics" to illustrate conditional probability:</p>
<blockquote>
<p>"Consider a continuously stirred reactor vessel where a chemical reaction takes place. On one side fluid or gas flows in, and it flows out on the other side... | g57982 | [
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0.018499232828617096,
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0.008... |
<p>I'm trying to build a recommendation system, but I only have data on what my user's have "liked" i.e. all non-missing data has the same numeric value. Is it possible for me to using matrix factorization methods without actually having "ratings?" (multiple numeric values for user ratings rather than just an indicato... | g57983 | [
-0.025203762575984,
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0.0017838272033259273,
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0.005756832659244537,
0.03596849367022514,
0.032788828015327454,
... |
<p>I read on the mcl documentation that the inflation parameter can be used to tune the granularity of the clusters. I am not very familiar with graph theory. What is the granularity of the clusters? Can I use this inflation parameter to choose to keep the clusters for which the nodes are very interconnected? (If, for ... | g33375 | [
-0.008171743713319302,
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0.030012372881174088,
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0.033874787390232086,
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-0.... |
<p>I'm trying to go from a radial distribution in polar coordinates to cartesian coordinates. I'm using Matlab and have tried pol2cart, but are having some trouble getting a matrix with probabilities.</p>
<p>The distribution is a log-normal along the radius, homogenous along theta.What I'd like to have is a 2D matrix ... | g57984 | [
0.0020306601654738188,
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0.0021998179145157337,
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0.004065150860697031,
0.04024747759103775,
0.02347910776734352,
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-0.... |
<p>In ridge regression with design matrix $X$, outcomes $y$, fixed regularization parameter $\lambda$, and errors $\epsilon\sim\mathcal{N}(0, \sigma^2I)$, the computations for the ridge regression coefficients $\hat\beta$ (aka the solution to $\arg\min_b \big[(y-Xb)'(y-Xb) + \lambda b'b\big]$) and their variance-covari... | g12850 | [
0.019391776993870735,
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0.09154444187879562,
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0.015063522383570671,
0.018136968836188316,
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0.06300490349531174,
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0.07546387612819672,
0.0041904691606760025,
0.0... |
<p>I have implemented Binary RBM in Matlab. I am using 60000 images as an input to train RBM. It takes approximately 11.3 minutes. I used tic and toc functions to evaluate above mentioned elapsed time. Is that, looks reasonable time? or it is slow?</p> | g57985 | [
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0.011783570982515812,
0.01981883868575096,
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0.056553155183792114,
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0.07529287040233612,
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0.0018116045976057649,
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0.013873754069209099,
0.03876585140824318,
0.019... |
<p>I am currently analysing a 1100-observation dataset of open-question responses. I was wondering whether I could really do a segmentation based on these responses.</p>
<p>What I've done is so far is conducted a qualitative coding of each response, and then produced a binomial variable for each of the codes, like thi... | g12852 | [
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0.014960123226046562,
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0.06579938530921936,
0... |
<p>I am currently working on forecasting the impressions an ad campaign will get given certain constraints specified by the ad provider (eg. only target men in California on websites with certain capabilities). I have forecast the total views all ad spaces will get using an ARIMA model in R. I now need to find some way... | g57986 | [
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0.05961581692099571,
0.03564916178584099,
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0.... |
<p>Can somebody explain to me the difference between linear model and loess model in statistics? I need to explain this to non-math people.</p> | g41635 | [
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0.05946306884288788,
... |
<p>I need to find the geometric mean of 0 and 600. Would it just be the square root of 600? I know that the formula is
$$
\bar x_{\mathrm{GM}} = \left(x_1 x_2 \cdots x_n\right)^{1/n},
$$
but in this case one of my values is 0, so I'm not sure.</p> | g57987 | [
-0.00954909436404705,
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0.025440489873290062,
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0.05845923349261284,
0.0036491970531642437,
-... |
<p>I was reading this <a href="http://eprints.soton.ac.uk/259182/1/gp2.pdf" rel="nofollow">paper</a> related to online Gaussian processes. </p>
<p><img src="http://i.stack.imgur.com/3MWl9.png" alt="enter image description here">
<img src="http://i.stack.imgur.com/liJHA.png" alt="enter image description here"></p>
<p>... | g10 | [
0.03401700034737587,
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0.052477121353149414,
0.08189361542463303,
0.0026... |
<p>What does the $MI(X,Y)$ convey about $Y$, when one of the probability distributions, $X$ is trivial and has all the probability concentrated at a single point?</p> | g57988 | [
0.02467966265976429,
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0.030967049300670624,
0.04219185188412666,
-0.0... |
<p>I am running a GEE negative binomial regression to see how predictors affect the onset of violence through time.</p>
<p>I have an $X$ variable (vegetation cover) which is calculated as whether an observation differed positively or negatively from the mean of the overall $X$ variable. It was calculated from raw valu... | g49738 | [
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0.0... |
<p>In a part of my research, I am fitting probability distribution models for the count data(and binomial data) using Poisson, Binomial, Negative Binomial and Beta Binomial models. I have few data sets in which the observed frequency and hence the expected modeled frequencies are too small(less than 5).. I want to comp... | g27275 | [
0.03778747841715813,
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0.017132755368947983,
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0.00948655977845192,
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0.... |
<p>I'm trying to get a MANOVA running to get Wilk's Lambda from the summary but I get a constant "need multiple responses" error. Looking at past answers I figured that one of the variables might be missing from the data frame but it doesn't seem like it..</p>
<p>here's head(data):</p>
<pre><code>head(data)
ror... | g57989 | [
-0.019039349630475044,
-0.03723715618252754,
-0.007584218867123127,
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0.028931308537721634,
0.0396711640059948,
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-0.02259816601872444,
-0.03736186772584915,
0.04092961922287941,
0.01966116391122341,
0.027... |
<p>My data shows 95% CI = [-1.07, -0.40], what does the negative sign indicate and how do I interpret the data? as I think it is significant for not capturing the value of 0.</p> | g57990 | [
0.012937952764332294,
0.014550456777215004,
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0.010170452296733856,
-0.05572899803519249,
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0.04484759271144867,
0.044886499643325806,
0.029... |
<p>I have an empirical distribution $G(x)$. I calculate it as follows</p>
<pre><code> x <- seq(0, 1000, 0.1)
g <- ecdf(var1)
G <- g(x)
</code></pre>
<p>I denote $h(x) = dG/dx$, i.e., $h$ is the pdf while $G$ is the cdf. </p>
<p>I now want to solve an equation for the upper limit of integration (s... | g57991 | [
0.026472581550478935,
0.014252547174692154,
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0.033164676278829575,
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0.009706342592835426,
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0.027942746877670288,
0.023557007312774658,
0.... |
<p>I run some Poisson regressions with the following results: (with number of associations an individual belongs to as the dependent variable)</p>
<pre><code>Coefficients:
Estimate Std. Error z value
(Intercept) -0.92 0.11 -8.43
age(decades) 0.07 0.01 5.64
f... | g57992 | [
-0.05580497533082962,
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0.07604474574327469,
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-0.003958001732826233,
-0.04766620695590973,
0.03155605494976044,
0.008597648702561855,
... |
<p>I need to identify relationships between multiple 'counting' independent variables (representing numbers of amino acids in a protein sequence) and one ordered categorical dependent variable (an experimental outcome) which assumes values between 1 and 7.</p>
<p>The distribution of the dependent variable looks the fo... | g12857 | [
0.014834080822765827,
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-0.002024923451244831,
-0.03822613134980202,
-0.004052788019180298,
0.035051681101322174,
... |
<p>I have a multilevel problem where I want to have a random intercept and a random slope. However the random slope is the interaction of two predictors. In this case, do I also have to allow random slopes for the individual predictors?</p>
<p>For example, with lme4 is this OK?</p>
<p>lmer(y ~ x + w + x:w + (1 + x:w|... | g12858 | [
0.005138624459505081,
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0.023574424907565117,
0.015936704352498055,
0.009231125004589558,
0... |
<p>My supervisor asked me to benchmark my method in classifying speech signal with other language. I am doing Malay language speech recognition. To benchmark my method/feature used, I need to test English speech. I am wondering, while doing testing (on the English data), should I use English data as training and testi... | g57993 | [
0.07505794614553452,
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0.015470882877707481,
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0.038623739033937454,
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0.025265740230679512,
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-0.041294097900390625,
0.03339403495192528,
0.05042595416307449,
-0.0025825549382716417,
0... |
<p>I have the following data,</p>
<pre><code>These are the x and y values to find correlation
x=115778,171235,1
y_a=31920,49327,0
y_b=83858,121908,1
cor_a= 0.99947573036 // These are the correlation values using numpy (x,y_a)
cor_b= 0.999915675755 // (x,y_b)
test_statistic_a= 30.870014264 // test statistic value... | g57994 | [
0.0405527800321579,
-0.006714708637446165,
-0.005803221371024847,
-0.032451607286930084,
0.016469746828079224,
-0.024887362495064735,
0.03965052217245102,
-0.026845674961805344,
-0.008516144007444382,
-0.0502631701529026,
-0.020850101485848427,
0.009146817028522491,
-0.004580087028443813,
... |
<p>I was conducted one-way ANOVA analysis to examone the level of knowledge shaorng among the employees based on there age differences. One-way ANOVA indicated that there were significant differences in the level on KS while Tukey post-hoc test revealed that there were no statistically significant differences on the le... | g49322 | [
-0.028622666373848915,
-0.01576131395995617,
-0.016856558620929718,
-0.009314097464084625,
-0.0229473989456892,
0.02394135668873787,
0.045757923275232315,
-0.01269223541021347,
-0.027538251131772995,
-0.0027075661346316338,
0.010995536111295223,
0.011824140325188637,
0.01739385351538658,
0... |
<p>I'm having trouble understanding ROC curve.</p>
<p>Is there any advantage/improvement in area under the ROC curve if I build different models from each unique subset of train set and use it to produce probability?
For example, if y has values of $\{a, a, a, a, b, b, b, b\}$, I build model $A$ by using $a$ from 1st/... | g12860 | [
0.018627876415848732,
-0.025573331862688065,
0.0110092181712389,
-0.006147317588329315,
0.034153323620557785,
-0.03064185380935669,
0.07114674896001816,
-0.005398282781243324,
-0.048165012151002884,
-0.06407743692398071,
-0.010615972802042961,
0.011081996373832226,
0.06337302923202515,
-0.... |
<p>The <a href="http://cran.r-project.org/web/packages/neuralnet/neuralnet.pdf" rel="nofollow">'neuralnet' package in R</a> allows us to use neural network algorithm with backpropagation. I want to use the function for prediction. I saw a tutorial on neuralnet in which predictions on the <a href="http://stat.ethz.ch/R-... | g57995 | [
0.0019940712954849005,
0.013630928471684456,
-0.005899130832403898,
-0.0026907813735306263,
0.021774616092443466,
-0.11204034090042114,
0.10057630389928818,
0.10086062550544739,
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-0.023578403517603874,
-0.02169983834028244,
0.07476429641246796,
0.03653543069958687,
0.00... |
<p>Traditionally a weak stationary process is also called covariance stationary, but those 3 properties are exposed:</p>
<p>$$E[Xt] = μ , \forall t$$
$$var(Xt) = \sigma^2, \forall t$$
$$cov(Xt, Xt−j) = \gamma_j, \forall t$$</p>
<p>that are respectively mean, variance and covariance stationarity.
We can merge 2 and 3 ... | g15054 | [
0.044672731310129166,
-0.03722476586699486,
0.025804897770285606,
-0.058105770498514175,
0.060866210609674454,
0.009311076253652573,
0.016292942687869072,
0.0261684563010931,
0.01111172791570425,
0.023104414343833923,
-0.011609290726482868,
-0.013377237133681774,
-0.03113676980137825,
0.04... |
<p>I am reading <a href="https://www.cs.princeton.edu/courses/archive/fall03/cs597F/Articles/biclustering_of_expression_data.pdf" rel="nofollow">Biclustering of expression data (Cheng and Church, 2000)</a></p>
<p>The paper is about the Cheng and Church biclustering algorithm and its main metric, the mean squared resid... | g57996 | [
0.015304259024560452,
-0.019062630832195282,
-0.025770125910639763,
-0.09722469747066498,
0.004979453049600124,
-0.07232339680194855,
-0.014252869412302971,
0.037530023604631424,
-0.03564895689487457,
0.008556184358894825,
-0.05914696678519249,
0.07400301098823547,
0.04936618357896805,
-0.... |
<p>This is an extension from <a href="http://stats.stackexchange.com/questions/63863/what-is-the-benefit-of-using-permutation-test/63868">my last post</a>. It seems to be too long to discuss there.</p>
<ul>
<li><p>When testing some null $H$ versus alternative $K$ by a test statistic $U(X)$, the p-value for $U$ on a s... | g57997 | [
0.0038297513965517282,
0.02916000597178936,
-0.027250520884990692,
-0.04515565559267998,
0.005119622685015202,
-0.06940402835607529,
-0.013382050208747387,
0.017978863790631294,
-0.008532095700502396,
-0.04206083342432976,
-0.012275354005396366,
0.03360319510102272,
0.02073381282389164,
0.... |
<p>I want to test if three types of learning mehods have different effects on the progression between two exams.</p>
<p>The data was collected like this:</p>
<ul>
<li><p>A first exam was done with all participants. They had various level of knowledge of the subject, ranging from expert to novice.</p></li>
<li><p>The ... | g57998 | [
0.005967704579234123,
-0.021679190918803215,
0.0048903897404670715,
0.0005182703025639057,
-0.0009086696663871408,
-0.008376853540539742,
0.026729641482234,
0.009959951974451542,
-0.016342144459486008,
0.008584275841712952,
0.03060397505760193,
0.015848251059651375,
0.03490125760436058,
0.... |
<p>I was trying to gain some intuition for Gaussian Process regression, so I made a simple 1D toy problem to try out. I took $x_i=\{1,2,3\}$ as the inputs, and $y_i=\{1,4,9\}$ as the responses. ('Inspired' from $y=x^2$)</p>
<p>For the regression I used a standard squared exponential kernel function:</p>
<p>$$k(x_p,x_... | g12865 | [
-0.01745966635644436,
-0.023488691076636314,
-0.01747303083539009,
-0.039391063153743744,
0.025358200073242188,
0.020697588101029396,
0.04982230067253113,
0.002476942026987672,
-0.0319429449737072,
-0.033464379608631134,
-0.0014097050298005342,
0.014170031994581223,
-0.0032557309605181217,
... |
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