question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I am working in program R. I am modeling the incidence of flight in a seabird in relation to distance to the nearest ship (potential disturbance, range = 0 to 74 km from the bird). 1= flight during observation, 0 = no flight. The bird does fly with some unknown probability when no ships are present or really "far" a... | g780 | [
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<p>I'm trying to assess performance of a supervised machine learning classification algorithm. The observations fall into nominal classes (2 for the time being, however I'd like to generalize this to multi-class problems), drawn from a population of 99 subjects.</p>
<p>One of the questions I'd like to be able to answe... | g66888 | [
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<p>Considering that we want to use optimize() on the interval [0,1] how can I write an R code for finding the value of β that produces the minimum forecast error without using external packages like <code>forecast</code>?</p>
<p><img src="http://i.stack.imgur.com/DE1Hn.png" alt="enter image description here"></p>
<p>... | g66889 | [
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<p>a tire manufacturer believes that the treadlife of its snow tires can be described by a NOrmal model with a mean of 32 thousand miles and standard deviation of 2.5 thousand miles. Based on this information answer the following questions</p>
<ol>
<li>What fraction of these tires can be expected to last less than 30 ... | g49760 | [
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<p>I have a multi-class .model trained with LibSVM. Is there a way to decompose this model into different binary .model files? For example, if I have a .model trained for $n$ classes, I would like to have $(n-1)/2$ binary classifiers separately. As far as I know, LibSVM trains one vs one in order to obtain the multi-cl... | g26162 | [
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<p>Hi I am using SPSS to compare two groups on ordingal data (frequency of substance use): never, 1-5/week, 6-10 week etc. The substance use data is highly skewed and non-transformable so ANOVA is out. I tried a Mann-Whitney U-test but SPSS gives error that ordinal data can not be entered. Moreover I need to covary for... | g26165 | [
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<p>Can the lack of main effect have the same underlying cause as the lack of interaction in 2-way ANOVA?</p>
<p>My results failed to reach significance for variables of gender and language. Is it possible that a confounding variable which affected language (and thus made it impossible for main effect of language to re... | g26166 | [
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<p>For an online unsupervised learning algorithm, data-points are learned sequentially. The performance may improve if in addition to the unlabelled data we have some labelled data-points (i.e. semi-supervised learning with a small amount of labelled data). In this situation, it may be attractive to let the algorithm d... | g26167 | [
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<p>I am in a situation where I have sample with $n=19$, and the the data are not normally distributed (according to the results of a Kolmogorov-Smirnov test) for all the variables. The data were collected using Likert scales in a questionnaire.
So now I am unsure whether or not I can use a parametric test or whether ... | g46600 | [
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<p>Please, i need to do a network meta-analysis and metaregression or a multivariate meta analysis and metaregression. I have multi arm randomized controlled studies.
I tried the metafor package</p>
<h1>Dummy database with controlled multiarm treatment studies</h1>
<pre><code>Study = c(1,2,3,1:2,4:10,1,2,7)
Group1 = ... | g66890 | [
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<p>I have this picture in <a href="http://rads.stackoverflow.com/amzn/click/0534349749" rel="nofollow">Lattin</a> representing structure and pattern loadings in factor analysis. If $Z$ (an observed variable) $=w_1 F_1+w_2 F_2$ (according to factor model), then the <em>pattern</em> loadings of $Z$ on $F_1$ and $F_2$ mus... | g26171 | [
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<p>I'm puzzled: what does a Greek $\Gamma$ mean in statistics? For example, here <a href="http://en.wikipedia.org/wiki/Weibull_distribution" rel="nofollow">http://en.wikipedia.org/wiki/Weibull_distribution</a> in the definition of the mean.</p> | g66891 | [
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<p>I am not sure if my title reflects what I am attempting to ask. Let me elaborate my question. I want to classify an observation/feature into one of two categories ($A$ and $B$) based on frequency of occurrence of feature in each category. For example, a particular observation occurs $x$ times in category A and $y$... | g6202 | [
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<p>The Mahalanobis distance of an observation vector $X$ from a set of observations is defined as $d=\sqrt{(\vec{x}-\vec{\mu})^T S^{-1} (\vec{x}-\vec{\mu})}$ where $S$ is the sample covariance matrix and $\mu$ is the sample mean of the set of observations to which we calculate the distance of $X$. I was wondering why w... | g49761 | [
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<p>Given a mathematical model $Y\widetilde Y(X_i)$, where $X_i=x_i^*$ represents a particular point estimate for input variable $X_i$. In sensitivity analysis, Sobol indices explain the importance of an input factor $X_i$ on the variance of the output $Y$ such that:</p>
<p>\begin{equation}
S_i=\displaystyle \dfrac{V_{... | g66892 | [
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<p>I am confused about some aspects of spatial autocorrelation usind survey data (survey which is repeated every year). I have data from 1991 to 2012 with sampling region pretty consistent every year. I am studying the species distribtion of two species in the area, in this goal I used binomial GLM. After running the G... | g66893 | [
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<p>Are you aware of any examples of election forensics in practice? Or at least any applied research on real large-scale datasets (e.g. govermental elections)? Thanks.</p> | g66894 | [
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<p>I don't have a strong background in statistics, so forgive me if I'm making very elementary mistakes here or if this question is too simplistic.</p>
<p>I am in a club with ~80 members, and every week, 10 members are selected to win a prize.</p>
<p>No member can be selected to win a prize twice in a row, but other ... | g66895 | [
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<p>I've got an easy question concerning residual analysis. So when I compute a QQ-Plot with standardized residuals $\widehat{d}$ on the y-axis and I observe normal distributed standardized residuals, why can I assume that the error term $u$ is normal distributed? I'd think that if $\widehat{d}$ looks normal distributed... | g66896 | [
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<p>Also, what will tend to produce a CI in which the sample value is far above the center, or far below the center?</p> | g66897 | [
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<ol>
<li>How do you carry out analysis of covariance using R? </li>
<li>How do you interpret the results? </li>
<li>A practical example will be highly appreciated.</li>
</ol> | g66898 | [
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<p>Is there a formal statistical test to test if process is a white noise?</p> | g66899 | [
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<p>Suppose a time-serie like this on the left-top corner with weekend and daily fluctuations. This time-series need differencing due to the rising ACF (bottom-left) and portmanteau tests' p -values too small, the weekend must be differenced away. Now I want to differentiate away the weekend-fluctuation in R, how to do ... | g46957 | [
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<p>What is the best way of defining white noise process so it is intuitive and easy to understand?</p> | g26180 | [
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<p>This is more of a conceptual question.
I have a coefficient estimate of .80 in a linear regression model with one IV and one dependent variable. However, plotting the data I see distinct groups, differing by the intercept.
I have about 300 additional variables in the data set that could have (or could not have; may... | g66900 | [
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<p>Random assignment is valuable because it ensures independence of treatment from potential outcomes. That is how it leads to unbiased estimates of the average treatment effect. But other assignment schemes can also systematically ensure independence of treatment from potential outcomes. So why do we need random as... | g6264 | [
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<p>With continuous data, a linear regression $Y=\beta_1+\beta_2X_2+u$ assumes that the error term is distributed N(0,$\sigma^2$)</p>
<p>1) Do we assume that Var(Y|x) is likewise ~N(0,$\sigma^2$)?</p>
<p>2) What is this error distribution in logistic regression? When the data is in the form of 1 record per case, where... | g44625 | [
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<p>I'm trying to understand the "classic" <a href="http://en.wikipedia.org/wiki/Iterative_proportional_fitting" rel="nofollow">iterative proportional fitting</a> (IPF) algorithm.</p>
<p>Does it always assume that the variables being analyzed are independent? If the variables are independent, then can't we just compute... | g66901 | [
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<p>Is it "okay" to add a vertical line to a histogram to visualize the mean value? </p>
<p>It seems okay to me, but I've never seen this in textbooks and the likes, so I'm wondering if there's some sort of convention not to do that? </p>
<p>The graph is for a term paper, I just want to make sure I don't accidentally ... | g66902 | [
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<p>When building predictive models (binary target), one of the principal methods I use for determining how useful the model is, is to plot the true proportion of y=1 values for each decile of the probability score. [These models are marketing models involving rare events and accuracy or the like are not suitable method... | g46622 | [
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<p>In social science it is comon to use sample weight to post adjust the sample so that it fits to a given basci population. There are algorithms to calculate how many cases you need to have a representive sample of the population. But often we would like to analyse a bit deeper than just the sample as a whole e.g. mal... | g46623 | [
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<p><a href="http://stackoverflow.com/questions/3949226/calculating-pearson-correlation-and-significance-in-python/7939259#7939259">This stackoverflow post</a> describes computing a Pearson correlation of [1,2,3] and [1,5,7] in several different ways in Python. The most straightforward implementation from <a href="http:... | g66903 | [
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-0.032615307718515396,
-0.024219410493969917,
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0.011335001327097416,
0.0... |
<p>For my microsimulation, I want to use R to predict values and draw a random sample based on this prediction.</p>
<p>To clarify my point: I want to simulate the number of chronic conditions people suffer from ($y_t$) at a certain point in time. I have a few waves of panel data available to estimate a relation betwee... | g6280 | [
-0.020832717418670654,
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0.0074971457943320274,
0.012151622213423252,
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... |
<p>Suppose we have $n$ covariates $x_1, \dots, x_n$ and a binary outcome variable $y$. Some of these covariates are categorical with multiple levels. Others are continuous. How would you choose the "best" model? In other words, how do you choose which covariates to include in the model?</p>
<p>Would you model $y$ with... | g49720 | [
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0.008749276399612427,
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0.06211036816239357,
0.03... |
<p>Like if I was given a P(A) of .5 and a P(B) value of .4 how would I get the minimum of the P(A∩B)?</p> | g66904 | [
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<p>I understand the Max likelihood estimators for mu and sigma for the lognormal distribution when data are actual values. However I need to understand how these formulas are modified when data are already grouped or binned (and actual values are not available). Specifically, for mu, the mle estimator is the sum of t... | g66905 | [
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0.0172... |
<p>Suppose I have two I(1) time series X and Y, and I want to know whether X and Y are "related" (for some definition of "related").</p>
<p>The standard cointegration approach defines relationship as cointegration, and says that X and Y are cointegrated if some linear combination of X and Y is stationary. To test whet... | g44658 | [
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<p>I have 3,000 observations (administrative communities) characterized by five variables. Four of them work in the direction 'the more, the worse' and one goes in the opposite.</p>
<p>I'd like to create one score or an ordered list of these observations that will best take into account all of those five variables.</p... | g66906 | [
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<p>I have a set of around 500 responses to a online survey that offered an incentive to complete. While most of the data appears to be valid, it's clear that some people were able to get around the (inadequate) browser cookie-based duplicate survey protection. Some respondents clearly randomly clicked through the surve... | g46628 | [
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<p>I'm talking with my advisor about how to compute standard deviations for, say, combined standardized test scores for admissions purposes. For example, we'd be interested to compute the sum of the verbal and quantitative scores from the GRE, which are correlated, and normed to be approximately normal.</p>
<p>More fo... | g66907 | [
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-... |
<p>Let's assume I have a set of samples of a random variable</p>
<p>$$
X = Y + Z \>,
$$</p>
<p>where $Y$ is Gaussian (with a mean of zero and variance $\sigma^2$) and $Z$ has a symmetric $\alpha$-stable distribution with index of stability $\alpha$ and scale parameter $c$. I know $\alpha$, but I don't know $\sigma... | g44662 | [
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<p>In order to test the Matrix package in R, I ran the following piece of code:</p>
<pre><code>library(Matrix)
p <- 50; n <- 500
a0 <- sample(1:(n*p), n*p*0.1)
d1 <- (a0-1) %% n
d2 <- floor((a0-d1)/n)
d0 <- cbind(d1+1, d2+1)
x0 <- Matrix(0, n, p, forceCheck=TRUE)
x0[d0] <- rnorm(n*p*0.1, 10, 1... | g46629 | [
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... |
<p>In this case, "generic" being the entire gauntlet of macroeconomic time-series that private and government statistical offices put out.</p>
<p>Some background - I recently started working at a data provider - we collect data releases and repackage them in a presumably more convenient and accessible fashion for our ... | g66908 | [
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<p>Given the prior probability of 2 distributions, $N(x,y)$ and $N(a,b)$, where $N(\mu,\sigma^2)$:</p>
<p>How do you make a decision rule to minimize the probability of error, if the prior probabilities are equal? Can you give an example?</p>
<p>What if the prior probabilities are different, such as<br>
$P(\text{Dist... | g26193 | [
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<p>Building on the post <a href="http://stats.stackexchange.com/questions/2910/how-to-efficiently-manage-a-statistical-analysis-project">How to efficiently manage a statistical analysis project</a> and the <a href="http://www.johnmyleswhite.com/notebook/2010/08/26/projecttemplate/"><code>ProjectTemplate</code> package... | g66909 | [
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<p>For OLS parameter estimates to be consistent it must be the case that
E(u|x)=0. Is it true?
E(u|x)=0 is a required condition for unbiasedness. But as far as I understand, unbiasedness does not necessarily mean consistency. Therefore I am really confused.</p> | g6305 | [
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<p>I came up with an idea to use machine learning for automatic grading of topic-specific texts. </p>
<p>More specifically, I will first use normal text classification techniques to sort all candidate texts into topics. Then, I want to be able to <strong>judge the quality of texts in specific topics</strong>:</p>
<p>... | g26195 | [
0.039711445569992065,
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0.015104888938367367,
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0.010208841413259506,
0.06962918490171432,
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0.10213806480169296,
0.003... |
<p>Problem: Two people are to arrive at the same location some time between 3pm and 4pm. They both arrive at random times within the hour and only stay for ten minutes. Since they only go one time, what is the probability that they will meet during that hour?</p>
<p>I have found the correct answer to this problem here... | g49312 | [
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0.04555974155664444,
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<p>In a Pick 3 lottery three numbers are drawn from three separate sets of numbers, between 0 and 9.
Matching 2 winning numbers, one of them duplicated, can be done in 3 ways, according to all lotteries websites.
But I found 18 ways to do it.
As an example:
If the winning numbers are 1 2 3, then there are 18 possible w... | g26201 | [
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0.04097723215818405,
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-... |
<p>I wish to build Feed-forward GMDH-type Neural Network model in R.
The most popular base function used in GMDH is the gradually complicated Kolmogorov-Gabor polynomial as explained in wikipedia.
Any guidance with package/code etc. would be great.</p>
<p>Regards,
purnendumaity</p> | g66910 | [
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0.01954180747270584,
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0... |
<p>Is there a better way to increase <strong>Recall Rate</strong> when using SIFT features?<br>
I am thinking a way to replace the NN1/NN2 ratio to account for slightly distorted objects.<br>
Moving towards clustering and using BOW(Bag Of Words) seems a way but I need to do one-on-one match of objects in images rather ... | g66911 | [
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<p>Given the following data: $102, 40, 27, 108, 124, 113, 143, 100, 115, 128$</p>
<p>If $\sum_{i=1}^{10} X^2 = 112600$, what is the sample variance?</p>
<p>The correct answer is $1400$.</p>
<p>However, when I tried calculating in Excel, I got an answer of $34,047,397$.</p>
<p>I took each $X$ value, squared it, subt... | g66912 | [
0.004939063917845488,
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<p>I am going to improve my code to the Exponential smoothing I submitted to Statsmodel which can be found <a href="https://github.com/ccsv/statsmodels/blob/85b6421ff54bbda179e4331e2dc22b3169795b23/statsmodels/tsa/_expsmoothing" rel="nofollow">here</a>. The code handles 15 different variation Standard Exponential Smoot... | g26202 | [
0.03537632152438164,
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0.004449142143130302,
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0.07319015264511108,
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<p>I am working on a problem where I have to solve an optimization problem over a dataset of 6 variables (~300 data points per variable). The data set is a historical data set, unfortunately it is small and has fat tails. I could probably get some more points but not as many to make to change the size by an order of ma... | g66913 | [
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0.024397676810622215,
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<p>In <a href="http://en.wikipedia.org/wiki/Markov_chain_Monte_Carlo" rel="nofollow">MCMC</a> methods, I keep reading about <code>burn-in</code> time or the number of samples to <code>"burn"</code>. What is this exactly, and why is it needed?</p>
<h3>Update:</h3>
<p>Once MCMC stabilizes, does it remain stable? How is... | g26208 | [
0.013695022091269493,
0.0020220917649567127,
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0.03809729963541031,
0.05683689936995506,
0.... |
<p>My goal is to compare published regression weights estimated from a sample in another country, with those of the same model established on our data.There is ample evidence on the web that a Chow test is the best method to test equality of regression parameters, by combining two groups. But a problem emerges when the... | g26209 | [
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0.011947485618293285,
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... |
<p>I have 365 days of hourly data (24points each) of a prediction error (realised -pred_day_before).</p>
<p>I want to model the evolution of the prediction error as an ARMA process.</p>
<p>Matlab System Identification Toolbox offers an ARMA estimation PER time series, whilst I have 365 time series (with supposedly th... | g66914 | [
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<p>Watching a video by the "mathematicalmonk" on the web, I was wondering how to answer this kind of questions:</p>
<p>Given $X_1,\ldots,X_n\sim \mathcal{N}\left(\mu,\sigma^2\right)$. Assume that $\mu$ is unknown. Using the square loss $\mathcal{L}\left(a,b\right)=\left(a-b\right)^2$:</p>
<p>1) Does $\hat{\sigma}^2=\... | g66915 | [
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<p>I've been asked to review the literature for all studies that estimate the mean and median Blood Lead Level (BLL) in a certain country, and then perform a meta-analysis to come up with one overall value for the mean and median level. </p>
<p>Is such a thing typically done? I'm not interested in any "effect size," j... | g66916 | [
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<p>I'm very inexperienced in statistical analysis. I think my question is fairly basic so I hope I can get some good pointers so I will be able to learn more efficiently.</p>
<p>I have extensive hourly sales data of a website going back years and I would like to make predictions on what the most important metrics (mos... | g66917 | [
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<p>My study is related to determinants of corporate liquidity and I am working on eviews. My model gives durbin watson stat value 0.89. after applying fixed effect estimation the value changes to 1.47. should I still worry about autocorrelation and go for another remedy?
if I change my model into log-linear form, the D... | g26214 | [
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0.03235134109854698,
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<p>Is there a standard name for a situation where a random variable follows a distribution whose parameter is another random variable ? For example a binomial(15,p) variable where the the p is distributed as beta(1,2), or a Poisson(Y) where Y is distributed as exponential(2)</p>
<p>Is this called a compound distributi... | g46642 | [
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<p>Suppose that A and B are mutually exclusive events for which P(A) = .3 and P(B) = .5. What is the probability that </p>
<pre><code>(a) either A or B occurs?
(b) A occurs but B does not?
(c) both A and B occur?
</code></pre>
<p>Trying to understand how to solve this problem, I solved (a) and got .15 (by .3*.... | g14651 | [
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<p>Apologies in advance for the tedious beginner question.</p>
<p>I'm trying to translate a least-squares problem from a manual process (using Excel for matrix transposition and multiplication) to using the Python <a href="http://statsmodels.sourceforge.net/devel/example_formulas.html#ols-regression-using-formulas" re... | g178 | [
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<p>Suppose I have a linear model predicting class-membership from a set of predictors. Now, I am going to classify a new observation which has, however, some predictor values missing. How can I deal with such situation? I know there are methods for imputing the missing values but I would like to avoid this and to use o... | g66918 | [
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<ol>
<li><p>Random Forests (RFs) is a competitive data modeling/mining method.</p></li>
<li><p>An RF model has one output -- the output/prediction variable.</p></li>
<li><p>The naive approach to modeling multiple outputs with RFs would be
to construct an RF for each output variable. So we have N independent
models, and... | g26215 | [
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<p>When training a model a train, a validation and test set are used.
I was wondering if there is any paper or example that proves that the use of an independent validation set increase the performance of the lasso estimator.
I am particularly interested in situations where the penalty value is chosen through cross v... | g66919 | [
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<p>We sell machinery. The following is graph is an <em>approximation</em> of units sold over time for a particular piece of equipment<sup>1</sup> :</p>
<p><img src="http://i.stack.imgur.com/uO6E3.png" alt="http://i.stack.imgur.com/3m3rM.png"></p>
<p>It starts out slow and slowly grows over time. I tried using linear ... | g66920 | [
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<p>Let us say we have an RxC table, when R and C are not necessarily equal, when is the maximum value of the Chi Square statistic achieved? and how can this be proven?</p> | g41024 | [
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<p>I was trying this optimization where I have some predictors and I want to predict the real value using weighted average of the predictors. What I am trying to do is given the predictors' prediction and the ground truth values, I will calculate the weighted average and the weighted average has weights defined k1,k2,.... | g66921 | [
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<p>I have conducted an analysis in which I start with a set of informed prior parameter distributions, and then conduct sequential analyses that constrain the distributions with data. </p>
<p>I am currently using density plots to visualize these results, but I am wondering how I can most effectively convey the process... | g46661 | [
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<p>I did a box cox plot on the ozone data in R. I need to determine the best transformation. Is there a way to get the exact confidence interval for lambda and the max. lambda or by just looking at the graph to estimate.(I dont know how to paste the graph). </p> | g66922 | [
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<p>I have three independent variables , and one moderating variable.
I'm studying the affect of these
variables on the decision to adopt electronic commerce.</p>
<p>I have a questionnaire, based on this questionnaire which is on a
7-point likert scale (from totally disagree which is coded 1 to
totally agree which is... | g66923 | [
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<p>I have two groups of data (with and without stimulus) from the same subject. For each experimental session, I measure a score (let say reaction times, n_with_stim=50, n_without_stim=50). For each day, the subject participates in four sessions (hence, n_with_stim_total=200, n_without_stim_total=200). My ultimate goal... | g66924 | [
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<p>I have data with the following empirical distribution<img src="http://i.stack.imgur.com/5okOh.png" alt="empirical distribution">. What would be a good model for it?</p>
<p>Edit: here is a closer view: </p>
<p><img src="http://i.stack.imgur.com/ZNnZY.png" alt="enter image description here"></p> | g46663 | [
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<p>I would like to know if there is a way to compare the relationship between a factor (length) and a response variable (lipid content) among multiple groups? I have given up on ANCOVA, as length is continuous. I am unsure if a multiple regression allows the use of a categorical variable (group membership) as an IV.</p... | g66925 | [
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... |
<p>I have a question regarding quantile regression. Supposing that I have 10000 observations with one response variable and several predictor variables in a dataset collected each year over several years. I run a multivariate quantile regression at 90% percentile. I want to compare the observed 90th percentile respo... | g66926 | [
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<p>I have a dataframe with 2 million rows and approximately 200 columns / features. Approximately 30-40% of the entries are blank. I am trying to find important features for a binary response variable. The predictors may be categorical or continuous. </p>
<p>I started with applying logistic regression, but having so ... | g66927 | [
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<p>This is my first post and I am a newby in pymc.
I am trying to model a non-linear system (see below for a further explanation). I create my synthetic data with:</p>
<pre><code>data = np.random.normal(8., data_std, 1000)
obs = pm.Normal("obs", coupling, value=data, observed=True)
</code></pre>
<p>My stochastic vari... | g66928 | [
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<p>I am currently working on a self-study question relating to exponential distribution. I made an attempt but was not able to make sense of the answer. When I looked up the reference guide, it offered the answer at 0.1068.</p>
<p>Appreciate any guidance and advice on where has my method gone wrong. Many thanks.</p>
... | g66929 | [
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<p>I have a text file document containing a set of words <code>strings</code> that I want to cluster. I want to use the <code>K-means</code> algorithm. As a distance I'll be using the <code>Levenshtein distance</code>.</p>
<p><strong>Question</strong></p>
<p>Usually if we have for example real number vectors we can j... | g26228 | [
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<p>I just started working with R and I could really use some help with this problem. I want to perform an ANOVA, to see how my independent factors (between-subject: Group) (within-subject (Modality, Violation, Correctness) interact with my dependent variable (EndQuestion.ACC). EndQuestion.ACC means whether a participan... | g66930 | [
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<p>I am attempting to perform a two-group confirmatory factor analysis (CFA) of one continuous factor on six ordinal predictors in <code>OpenMx</code> (<code>R</code>) using (robust) Weighted Least Squares (WLS) estimation. While I am completely new to OpenMx (I only used <code>sem</code> and <code>lavaan</code> ) I th... | g26229 | [
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<p>I am conducting a study which is looking at the effect of 'Condition' (Quiet, Intelligible, Unintelligible) on the pupil(eye) response over time. Upon visual inspection of my data plots, pupil response slopes appear to change in a curvilinear way and there appear to be differences in the timing and amplitude of peak... | g26230 | [
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<p>I have a question for adjusted $R^2$ given a specific regression model.</p>
<p>I am doing a project on January effect and I have a model from some journal using</p>
<p>$$R_i = a_0 + a_1D_{\mathrm{Jan}} + \varepsilon_i$$</p>
<p>where </p>
<ul>
<li><p>$R_i$ is daily return of portfolio/index,</p></li>
<li><p>$a_0... | g26232 | [
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<p>I'm a statistics newbie and I would like to make sense of the p-value with ANOVA, hopefully with a visual presentation. All online visual tools I've found so far only have MSB, MSE and F values visually presented (such as <a href="http://www.psych.utah.edu/aoce/tools/Anova/anovatool.html" rel="nofollow">this here</a... | g66931 | [
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<p>I am looking to run a series of performance tests for a software system across different configurations and determine which combination works best. The software system processes a number of files, does some work with them and writes them to a database.</p>
<p>In order to carry out these tests, I have a script that... | g26234 | [
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<p>I have data from an experiment that is testing how the order of two studying methods (visual or auditory) affects word recall. For analysis a multi-factor anova with a repeated measure is appropriate, but I am not sure if I am structuring my data correctly. </p>
<p>This is the command I'm using:
<code>aov(recalled_... | g46666 | [
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... |
<p>I have to run a factor analysis on a dataset made up of dichotomous variables (0=yes, 1= no) and I don´t know if I'm on the right track.</p>
<p>Using <code>tetrachoric()</code> I create a correlation matrix, on which I run <code>fa(data,factors=1)</code>.
The result is quite near to the results i receive when usin... | g66932 | [
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0.021458... |
<p>The following is a proof of the validity of the (bootstrap) percentile interval taken from Larry Wasserman's <a href="http://rads.stackoverflow.com/amzn/click/0387402721" rel="nofollow">"All of Statistics"</a>. $\theta^*_{\alpha/2}$ and $\theta^*_{1-\alpha/2}$ denote the respective quantiles of the bootstrap of our ... | g26240 | [
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<p>We have a deck of $n$ cards. We draw cards from it uniformly at random with replacement. After $2n$ draws what is the expected number of cards never chosen?</p>
<p>This question is part 2 of problem 2.12 in </p>
<blockquote>
<p>M. Mitzenmacher and E. Upfal, <em><a href="http://rads.stackoverflow.com/amzn/click/0... | g26241 | [
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<p>Can chi-square test be performed on data that does not have normal or gaussian distribution?</p>
<p>One of the chi-square tests I am performing results in percentage points less than the 12.59 (α=0.05, v=6) using cross-tabulation. Therefore, I cannot reject the null hypothesis. </p>
<p>Is there a test that I can p... | g66933 | [
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<p>I am working on machine translation evaluation, and am looking at ratings given by humans who are judging the quality of sentences produced by machine translation systems. The evaluators give fluency and adequacy (how well the information is preserved) scores to sentences. The data is from <a href="http://research.n... | g66934 | [
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0.016143115237355232,
-0.030741654336452484,
0.003405186580494046,
0.07075721025466919,
-0.03705208748579025,
-0.015567735768854618,
0.02518063224852085,
0.00022880782489664853,
0.03874313458800316,
0.... |
<p>I have difficulty in solving unit root test by using both <code>adf.test</code> and <code>pp.test</code> in R.</p>
<p>The result p-value using <code>adf.test</code> is 0.2677 (mean that it has unit root),
and the result p-value using <code>pp.test</code> is 0.01696 (mean that is has no unit root).</p>
<p>What mean... | g66935 | [
0.03488578274846077,
-0.011838501319289207,
0.005950321443378925,
-0.02123420685529709,
0.0703786164522171,
-0.06503674387931824,
0.045389946550130844,
0.05282367393374443,
-0.006936710327863693,
-0.018467692658305168,
-0.041328877210617065,
0.028976839035749435,
-0.01575026847422123,
0.04... |
<p>Given the setting of the birthday paradox ($n$ people with birthdays randomly drawn from the uniform distribution of 365 days), let us call the days on which at least one person was born <em>birthdays</em> and all other days <em>non-birthdays</em>. What can be said about the distribution of</p>
<p>a) The length in ... | g66936 | [
0.027143258601427078,
0.07113537937402725,
-0.029048077762126923,
-0.037969134747982025,
-0.012544405646622181,
-0.044865529984235764,
0.01316541712731123,
-0.00999984610825777,
0.028432022780179977,
-0.03546714410185814,
-0.014831156469881535,
0.011024987325072289,
0.04634840413928032,
0.... |
<p>If the process is: $(1-0.3L)(1-L)X_t=(1+0.5L)^2\epsilon_t$ what are the values of p,d and q in ARIMA (p,d,q)?
Thank you very much in advance.</p> | g49762 | [
-0.0025165898259729147,
0.02847255766391754,
-0.02597963809967041,
-0.027171587571501732,
0.059256188571453094,
-0.022514402866363525,
0.0479525662958622,
-0.04140515252947807,
-0.02525326982140541,
0.01783153787255287,
-0.07208877801895142,
0.0712912455201149,
0.06358024477958679,
-0.0056... |
<p>Is there a solid mathematical connection between ADABOOST and Q-learning that can inform "higher performance" machine learning algorithms?</p>
<p>Q-learning references:</p>
<ul>
<li><a href="http://www.autonlab.org/tutorials/rl.html" rel="nofollow">http://www.autonlab.org/tutorials/rl.html</a></li>
<li><a href="ht... | g26245 | [
0.03244026005268097,
0.07153727114200592,
0.013434570282697678,
-0.018578585237264633,
0.05263875797390938,
-0.03318113088607788,
0.03468581289052963,
-0.04335113614797592,
-0.010896917432546616,
-0.010662112385034561,
-0.02471565641462803,
0.008806338533759117,
0.12980762124061584,
0.0028... |
<p>Consider i.i.d observation vector ${\bf x}$ from a distribution $F$ depending on vector of parameters $\boldsymbol{\theta}$ and single parameter $\alpha$.</p>
<p>We would like to estimate parameters [$\boldsymbol{\theta}, \alpha$] using maximum likelihood estimation but we also know that $\alpha$ is a realisation f... | g66937 | [
0.005494421347975731,
-0.03795605152845383,
-0.00706642447039485,
0.017018087208271027,
0.015159513801336288,
-0.07287236303091049,
-0.017123090103268623,
0.03502442687749863,
-0.047088686376810074,
-0.0002517623361200094,
-0.04132862016558647,
0.0013077730545774102,
0.054206520318984985,
... |
<p>What exactly is a utility function of a survey question? For example, suppose a question has $7$ possible answer options. We assign each answer choice a number between $0$ and $100$. What information does this tell us?</p> | g26247 | [
-0.00995766744017601,
0.0517059825360775,
0.022950202226638794,
0.017952553927898407,
0.03265959396958351,
-0.02542792819440365,
-0.004568906966596842,
-0.023076115176081657,
0.02219814993441105,
-0.02212372235953808,
-0.0225682333111763,
-0.02577715553343296,
0.0359204038977623,
0.0275668... |
<p>I need to apply a regression model on observations that is not time series data but each observation presents a store and the amount of cartons that gets sent to that store. For instance <code>a_i = number of cartons sent to store i</code> and is my dependent variable. Each carton contains products of different kin... | g66938 | [
-0.013772044330835342,
0.010207373648881912,
-0.025413623079657555,
-0.05599629506468773,
-0.03872700408101082,
-0.0349208228290081,
0.040758904069662094,
-0.02670193463563919,
-0.05446353927254677,
0.002176733920350671,
0.0130650345236063,
0.051254939287900925,
0.07574854046106339,
-0.021... |
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