question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>In a survey, I used a measurement of uncertainty as a key dependent variable, and after implementing the measurement in 2 waves of my survey, I found a better measurement and this new measurement has better internal validity and fits better theoretically. I still have 2 waves of survey to be sent and I want to add ... | g58879 | [
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<p>Can anybody tell me how can I simulate a data set for comparing logit and probit model?
If I simulate a data from a standard multivariate normal distribution considering 5 variables then can I use one of them as continuous latent variable (for which I consider non-zero covariance in the covariance matrix)? If I can... | g14155 | [
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<p>I have 2 categorically dependent variables(both binomial) in logistic regression which individually both give positive estimates against the response(binomial). However if modeled together one give positive and other give negative. I checked for the multicollinearity using VIF, which seems fine. What could be the po... | g58880 | [
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<p>I have a numeric data sample with mean $\mu$ and standard deviation $\sigma$. I believe that this data has a normal distribution truncated to $[0,1]$. </p>
<ol>
<li><p>Is there a reasonably simple formula for estimating the parameters $\mu', \sigma'$ of that truncated normal distribution? Is there an R command whi... | g58881 | [
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<p>I have a repeated measures data set with each subject ($N = 32$) being measured with two repeats of two tasks at two levels. My values of the correlation coefficient $r$ are:</p>
<pre><code>1st repeat vs 2nd repeat: 0.6847
level 1 vs level 2: 0.6930
task A vs task B: 0.4081
</code></pre>
<p>The assumption is that ... | g58882 | [
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<p>To compare multiple groups, one usually runs ANOVA. If ANOVA rejects the null hypothesis, one goes through the multiple comparisons.</p>
<p>The multiple comparisons are necessary to establish which group is different. Multiple comparisons are performed applying Bonferroni correction (or more recent types of correc... | g49541 | [
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<p>I need to conduct a permutation analysis on unequal samples, one (X) with 579 data points, and another (Y) with 1289 data points. There is an obvious difference in the data. However, this difference may be due to the imbalance between sample sizes. I need to run a permutation analysis using all possible pairs (co... | g14161 | [
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<p>Using R: <code>pamk.best <- pamk(data,k=2:12,criterion="ch")</code> returns an estimation of the best number of clusters using Calinski-Harabasz criterion. However, this criterion cannot be used to evaluate the quality of 'one' cluster. Therefore, how can I know if it is better to divide the data into two groups ... | g58883 | [
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<p>On STAT101 your assessment is based on:
Final Exam 50%
Learn based on-line assessment 30%
Assignments 20%
Consider three random variables $X$, $Y$ and $Z$ which respectively represent the exam, on-line assessment total and assignment scores (out of 100%) of a randomly chosen student. Assume that $X$, $Y$ and $Z$ are... | g58884 | [
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<p>I need to train a restricted Boltzmann machine to model the joint probability of categorical variables. For this I adapted a Bernoulli RBM to have groups of softmax units in the visible layer. The <a href="https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/neural_network/rbm.py" rel="nofollow">original... | g58885 | [
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<p>I have $\boldsymbol{A} = \boldsymbol{G}^H \boldsymbol{G}$ is a Wishart matrix, i.e, $\boldsymbol{G}^H \boldsymbol{G} \sim \mathcal{W}_K (M, \boldsymbol{\Lambda})$ with $\boldsymbol{\Lambda} = \mathrm{diag} (\rho_1, \cdots, \rho_K)$. ($\boldsymbol{G}$ is $M \times K$ matrix ).</p>
<p>We know that $\boldsymbol{B} = (... | g58886 | [
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<p>I am having a problem with checking the assumptions for a continuous variable in a proportional hazards model. If a variable were a factor with many levels, then I could use the logrank test or check whether the log(-log) transformations of survival curves are parallel. But what if a variable is continuous? Is that ... | g11217 | [
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<p>I am planning on running the same benchmark tests (i.e. throughput, response time,..) in 3 environments: 1) a mobile device, 2) a virtual machine in VirtualBox, 3) a virtual machine on Amazon EC2.</p>
<p>What could be the best way to define the hypothesis, Null or Alternate when considering significant differences ... | g7527 | [
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<p>Do the pdf and the pmf and the cdf contain the same information?</p>
<p>For me the pdf gives the whole probability to a certain point(basically the area under the probability).</p>
<p>The pmf give the probability of a certain point.</p>
<p>The cdf give the probability under a certain point.</p>
<p>So to me the p... | g440 | [
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<p>I am trying to build a multivariate control chart but I did not find any good explanation of how to do that. </p>
<p>Starting with $x_0$ a part of the samples that are in control I compute $\mu_0$ and $\Sigma_0$ the mean and the covariance matrix. </p>
<p>Now with new data $x_n$ I compute $d= (\bar{x}_n-\mu_0)\Sig... | g440 | [
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<p>Good day,<br>
I'm working with a panel dataset, I've used many models,
homogeneous (fixed effect, pooled ols and Driscoll and Kraay)
heterogeneous (swamy random coefficients) and would like to do a
post-estimation to select the model that best fit my regression.
Is there any method, command that may allow me to d... | g58887 | [
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... |
<p>I'm wondering what the effect is if I don't include moderators in my model? Is this the same or different from an omitted variable bias? I am having a hard time grasping this conceptually.</p>
<p>More information: I did a GEE analysis for a binary outcome for a publication. The independent variables were the study ... | g58888 | [
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<p>The followgin formula is normally used for comparing two Pearsons $r$ correlations:</p>
<p><img src="http://i.stack.imgur.com/hxL5j.png" alt="Formula from Olkin und Siotani (1964)"></p>
<p>Can this formula also be used to compare correlations from Spearman's $\rho$ and Cramér's $V$? </p> | g58889 | [
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<p>I have to do some feature selection for a classification problem with numeric features. I am not sure which feature selection method to use. Chisquared test or Spearmann's rank correlation coefficient, which one would be the best. Any suggestion guys?</p> | g14168 | [
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<p>I counted the number of geese on an intertidal mudflat on 100+ days over the winter. I made two counts on each of these days: one at low tide and one at high tide. I want to know if the number of geese present differs at high and low tide. As the data are very positively skewed, using a Wilcoxon test is appropriate.... | g58890 | [
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<p>I am new to using linear mixed models and would greatly appreciate any help I can get.</p>
<p>I have an equation of the form $ y = X\beta + Zu + \epsilon$ where $u$ is a random effect whose covariance matrix I want to be a multiple of the identity matrix.</p>
<p>My matrix $Z$ has about 1000 columns. Trouble is I h... | g58891 | [
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<p>I am new to R. I am using the <code>plm</code> package to run pooled OLS and Fixed Effect. My data set has 130 countries over 33 years with lots of missing values. My model has 9 independent variables. When I run my models I get the following: </p>
<pre><code>Unbalanced Panel: n=34, T=1-6, N=61
</code></pre>
<p>Ca... | g14174 | [
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<p>My psychology dissertation will be a cluster analysis with one grouping variable. How do I know how many participants I need? I imagine there should not be more than 5 clusters. 79 items make up 9 attributes that the participants will be clustered on. I realize that power analysis is moot since cluster analysis ... | g58892 | [
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<p>i am wondering if there is an equivalent of PCA explained variance ratio for SVD. What are the measures I can get to monitor the number of columns I keep after the SVD ? Are any of these metrics implemented in sklearn/python or R ? </p> | g33607 | [
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<p>Let $x_1, x_2$ be random variables that follow truncated beta distributions:</p>
<p>$$f_{i}\left(x_{i}\right)=\frac{x_{i}^{\alpha_{i}-1}(1-x_{i})^{\beta_{i}-1}}{\mathrm{B}(a_{i},b_{i};\alpha_{i},\beta_{i})}$$</p>
<p>for $a_i\le x_i \le b_i$, and $f_i (x_i) = 0$ otherwise. Here $\mathrm{B}(a,b;\alpha,\beta)=\int_a^... | g58893 | [
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<p>I have a dataset with a clear question I want to answer, but I'm unsure of the best statistical approach to answer my question. Here's an example that matches the structure of my data:</p>
<p>Let's say we have a group of ~200 physicians for whom we measure 10 comparable quality measures (e.g. adherence to guideline... | g58894 | [
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<p>I recently read an online discussion about <a href="http://andrewgelman.com/2014/03/15/problematic-interpretations-confidence-intervals/#comment-155270" rel="nofollow">confidence levels and confidence intervals</a>. To be honest, I'm confused. What's the bottom line there? </p>
<p>For a specific statement, say,<... | g49464 | [
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<p>I'm running a Ridge regression with about 1200 parameters (and about 30000 datapoints). I noticed that for some values of ridge, the weights look qualitatively different beyond a certain point. </p>
<p>In particular, higher values for the ridge parameter will yield weights that clearly have some kind of structure t... | g58895 | [
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<p>I have a 2x3 contingency table - the row variable is a factor, the column variable is an ordered factor (ordinal level). I'd like to apply either symmetrical or asymmetrical association technique. What do you recommend me to do? Which technique do you find the most appropriate?</p> | g43246 | [
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<p>I've heard a bit about the 'kernel trick' for support vector machines, and I was wondering:</p>
<ol>
<li>How do you identify problems that might benefit from the kernel trick?</li>
<li>How to implement it in R?</li>
</ol>
<p>Thank you</p> | g43248 | [
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<p>I am taking a class in data mining and I am working on a term project using the <a href="http://www.cdc.gov/brfss/" rel="nofollow">BRFSS</a> dataset. I have a huge dataset with 405 columns and 12,000 rows. There are many columns which are completely empty. I was trying to remove empty columns using SAS, R or Excel b... | g58896 | [
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0.012143846601247787,
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0.07353339344263077,
... |
<p>I am having a problem computing the pearson correlation coefficient of data sets with possibly zero standard deviation (i.e. all data has the same value).</p>
<p>Suppose that I have the following two data sets:</p>
<pre><code>float x[] = {2, 2, 2, 3, 2};
float y[] = {2, 2, 2, 2, 2};
</code></pre>
<p>The correlati... | g58897 | [
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<p>I will be begin by saying that I am not very familiar with statistics. I am calculating a drought index and I have a set of values. The next step in the procedure is to standardize the values to allow for comparing across regions and time scales. The paper that establishes this particular drought index fits their... | g3165 | [
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... |
<p>Let's say I am interested in choosing a new country $c_1, \ldots, c_k$ to live in. For some reason I can only apply to one country and only once. <br></p>
<p>I know for each country a set of 2000 observations (persons), each consisting of 20 attributes and for each I know whether they were accepted or rejected. (I ... | g44707 | [
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<p>I have a bunch (around 1000) of estimates and they are all supposed to be estimates of long-run elasticity. A little more than half of these is estimated using method A and the rest using a method B. Somewhere I read something like "I think method B estimates something <em>very</em> different than method A, because ... | g14181 | [
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<p>The model is from sports. </p>
<p>I'm trying to predict the win percentage of each team in the next season based on information available before that season. I have about 240 observations of the numbers of wins in various seasons for various teams, along with the corresponding values of possible predictors. I want ... | g43256 | [
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<p>I have categorical data on Police Stations against Crime categories on a 2-way contingency table. I have an asymmetric row map and column map from correspondence analysis using XLSTAT. Which one of the two maps should be used to interpret the results?</p> | g58898 | [
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<p>I would like to fit a spatial generalized linear mixed model, for example, to model spatial count responses by using the Laplace approximation in available statistical software.</p>
<p>I am particularly interested in implementations in R. </p> | g46316 | [
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<p>I have a regression model that does not have any time variables and the ordering of the variables and their values does not matter when doing the regression. </p>
<p>Are autocorrelation tests like Durbin-Watson still applicable to this kind of data? </p> | g58899 | [
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<p>I have a pretty generic question which I am guessing could be relevant to many social scientists who deal with panel data sets. What are the best practices for making graphs about interaction effects.</p>
<p>There is a variety of articles that talk about packages like ggplot, ggplot2, sjPlot, effects and so on but ... | g21107 | [
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<p>I am trying to determine how to obtain within-group variance for a composite measure based on a set of (weighted) proportions. </p>
<p>I have 50 groups being compared on 8 proportion measures, with 4 measures weighted as 1/5 and 4 measures weighted at 1/20. There is a composite score for each group that is the 8 ra... | g58900 | [
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<p>When I run my analysis with items with zero variance, <code>sem</code> in <code>R</code> would throw up a warning saying that items with zero variance exist. I then move on to remove these from the analysis. My question is:</p>
<ol>
<li>Are there any other ways of resolving this problem besides removing the items p... | g43259 | [
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<p>I'm trying to compare gaze durations measured using an eye tracker for each word. Since longer words will naturally lead to longer gaze durations, simply comparing the values is inaccurate. </p>
<pre><code>gaze duration word length
100ms 6
250ms 8
150ms 7
</code></pre>
<p>A sim... | g46341 | [
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<p>Having a score board</p>
<pre><code> Points
Day 1 1000
Day 2 1050
Day 3 1010
Day 4 1010
Day 5 1030
</code></pre>
<p>How to calculate the average variation points? i.e. How many points, on average, a person gains or loses per day.</p>
<p>This must be something really simple. Yet, I can't figure ou... | g37822 | [
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<p>For my thesis I sent out a questionnaire that has 10 questions. I set defaults: the first seven question had the default set to the desired answer and the last three questions had the default set to the undesired answer. </p>
<p>I want to measure whether people followed the default using SPSS. I am thinking I shoul... | g58901 | [
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<p>One objective of a survey can be to understand the proportion male vs. female users. To the extent a specific gender correlates to particular use cases of a technology, product design, product/feature prioritization and marketing can be differently managed.</p>
<p>A survey of existing users will inherently have err... | g58902 | [
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<p>Thanks in advance for the advice.</p>
<p>I am trying to build a generalized linear model that has many predictors. The $R^{2}$ value of the model is quite low (.21), but when I use the model to predict against my validation set I am getting very good results.</p>
<p>I was under the impression that a low $R^{2}$ v... | g58903 | [
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0.0... |
<p>I have a regression problem that I implement in R using for loop. Basically, I have an equation (as a result of a long procedure) as a function of temperature, with five unknown parameters. I have 12 different temperatures that I can use to drive the equations, so for each combination of the five parameters, I can h... | g14191 | [
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... |
<p>Let´s say that my PCA analysis extracted 2 components, which explain 80% of the variance before rotation. The components were then rotated using oblique (Direct Oblimin) rotation, so SPSS cannot compute how much percentage of variance each component explain. When I plot the graph, usually editors require these perce... | g58904 | [
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<p>I wanted to compare how two different (independent) models perform under winbugs, So I created code like:</p>
<pre><code># likelihood
for (i in 1:sites) {
M[i] ~ dpois(lambda) # model 1
M2[i] ~ dpois(lambda2) # model 2
for (j in 1:sample) {
obs[i, j] <- sum(y[i, j,])
# model 1
... | g14192 | [
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0.006561766844242811,
0.022511843591928482,
0.0... |
<p>I have the following probability function:</p>
<p>$$\text{Prob} = \frac{1}{1 + e^{-z}}$$</p>
<p>where</p>
<p>$$z = B_0 + B_1X_1 + \dots + B_nX_n.$$</p>
<p>My model looks like</p>
<p>$$\Pr(Y=1) = \frac{1}{1 + \exp\left(-[-3.92 + 0.014\times(\text{gender})]\right)}$$</p>
<p>I understand what the intercept (3.92)... | g14196 | [
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0.03608354926109314,
0.04915700852870941,
0.0261... |
<p>I try to figure out how a logistic regression is handling data with a 0/1 dependent variable. 95% of the data are ones. The purpose of the model is to estimate the probability to be in one of the groups. Of course there are several explanatory variables included.</p>
<p>Fitting the model leads to unsatisfactory res... | g58905 | [
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0.05070880055427551,
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0.035351336002349854,
0... |
<p>When studying the time series analysis, I read the following example.</p>
<p><img src="http://i.stack.imgur.com/8FhDZ.png" alt="enter image description here"></p>
<p>I do not know how to understand this cancellation process. Yes, it can be cancelled like normal algebraic formula. But this “z” is an operator instea... | g14198 | [
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0.014462145045399666,
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0.008108625188469887,
0.08536513149738312,
0.049343615770339966,
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0.030576078221201897,
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0.07158789038658142,
0.03551297262310982,
0.02281... |
<p>I recently forecasted data using the H-W triple exp smoothing method which takes into account seasonality and trend.
The data I used was weekly data which presented number of phone calls a restaurant receives. I wanted to forecast (using 45 weeks of data), at least 10 weeks ahead. </p>
<p>This was my code:</p>
<p... | g58906 | [
0.01534305140376091,
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0.001112665981054306,
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0.03208297863602638,
0.0059839216992259026,
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-0.038793984800577164,
0.03645308315753937,
0.05905754119157791,
0.08313746005296707,
0.025... |
<p>Leaving aside the obvious issue of the low power of the chi-square in this sort of circumstance, imagine doing a chi-square goodness of test for some density with unspecified parameters, by binning the data.</p>
<p>For concreteness, let's say an exponential distribution with unknown mean and a sample size of say 10... | g58907 | [
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0.03554851561784744,
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0.052028559148311615,
0.0096... |
<p>This question is about specific strategies to deal with non-stationary variables in forecasting. </p>
<p>This problem usually rears its ugly head when you have a predictor whose levels are relevant to the response, but whose first difference carries very different information. Generally, if there is one or two of t... | g14200 | [
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0.0057691182009875774,
0.03770065680146217,
... |
<p>I'm running a quick simulation to compare different clustering methods, and currently hit a snag trying to evaluate the cluster solutions. </p>
<p>I know of various validation metrics (many found in <a href="http://www.statmethods.net/advstats/cluster.html" rel="nofollow">cluster.stats()</a> in R), but I assume tho... | g58908 | [
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0.007526482455432415,
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0.01668093539774418,
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0.08885808289051056,
0.0... |
<p>I have a dataset comprising two groups with 1 continuous covariate (ratio scale). The dependent variable is a count variable. The distribution of the dependent variable looks like this:</p>
<p><img src="http://i.stack.imgur.com/E768z.png" alt="Distribution of my variable of interest BY group"></p>
<p>I was wonderi... | g39393 | [
0.0052404883317649364,
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0.067790187895298,
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<p>I have daily revenue data from a small business with 6 locations. The business sells food products that range from roughly \$2.00 to \$9.00, mainly to professionals. They do over a million dollars a year in sales and are located in a major North American city (scattered around the downtown core / business district).... | g58909 | [
0.009144828654825687,
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0.003150475677102804,
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0.06981433182954788,
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0.0272379033267498,
0.027821732684969902,
0.05930304527282715,
-0.01... |
<p>When I read "moving average" in relation to a time series, I think something like $\frac{(x_{t-1} + x_{t-2} + x_{t-3})}3$, or perhaps a weighted average like $0.5x_{t-1} + 0.3x_{t-2} + 0.2x_{t-3}$. (I realize these are actually AR(3) models, but these are what my brain jumps to.) Why are MA(q) models formulas of e... | g49641 | [
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0.014006312936544418,
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0.03310103341937065,
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0.03230797499418259,
0.1209287941455841,
0.01... |
<p>I have 3 variables containing 1 TO 5 vote as key performance indicator (kpi) responses to a client survey. Using RapidMiner and logistic regression I noticed that they are mildly predictive of a particular negative event. I also analyzed frequency of this event for each vote: respondents who choose 1 (low score) in ... | g58910 | [
0.004935774486511946,
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0.02243013307452202,
0.021991482004523277,
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0.01580137014389038,
0.01950046606361866,
0.04194525256752968,
-0... |
<p>I am using nlme in a mixed model: Y = a + b + a*b.</p>
<pre><code>fm1<-lme(Y ~ a*b, data = example.ento.mn, random=~1| Exp/Plant)
</code></pre>
<p>a and b are fixed.</p>
<p>random error: experiment/plant.</p>
<p>This is what I got from anova table:</p>
<pre><code>anova(fm1, type="marginal")
... | g14201 | [
-0.046814143657684326,
-0.03962034359574318,
0.007476150058209896,
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0.... |
<p>I'm simulating a random collision process. At each time interval I calculate the probability of a collision occurring between each object and all other objects in proximity. Currently if I wish to find the total probability of a specific object being in a collision with any other object it is the sum of all these pr... | g58911 | [
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<p>I have the following table and need to answer the following questions. The first question does not appear to me to have enough information. </p>
<pre><code>Name Age MATH ENGLISH RESIDENCE
Tammy 16 C A CAMPUS
Peter 16 B A CAMPUS
Tom 17 C A CAMPUS
Lynn 18 A A CAMPUS
Michael 20 A... | g58912 | [
0.01775306649506092,
0.008131202310323715,
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0.010632496327161789,
0.024078398942947388,
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0.01081281341612339,
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0.03902256861329079,
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0.038... |
<p>I cannot say I am very familiar with ARMA (I must admit that I am kind of biased to begin with, so for a long time, I haven't tried to bother with AR/MA-like linear models).</p>
<p>However, for some reason, I tried ARMA to solve problems of forecasting the behavior of some very complicated dynamic systems, and I fo... | g58913 | [
0.01596786081790924,
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0.017826521769165993,
0.07716035842895508,
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0.12057314068078995,
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<p>I am using R princomp function (from stats package) to run a PCA on a data set and I want to compare its output to that of the nonlinear dimensionality reduction method ISOMAP, which I am using under matlab through this toolbox: <a href="http://isomap.stanford.edu" rel="nofollow">http://isomap.stanford.edu</a> on th... | g58914 | [
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<p>I, like many people, dislike statistical significance testing. I would much rather measure "practical significance" / effect size. </p>
<p>The problem is that I do not know of a "standard" way of doing so. Many people say that there is no standard way to measure practical significance -- it all depends on the probl... | g58915 | [
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<p>If there was a certification exam for statisticians, what would be the syllabus, including the recommended reading material (to give an idea of the level of the exam)? </p> | g14205 | [
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<p>I've found a variation of the $\chi^2$ statistic that looks like this:</p>
<p>$\chi^2 = \sum\limits_{i=1}^N\,\chi_i^2 = \sum\limits_{i=1}^N\,\frac{(\log m_{i}- \log n_{i})^2}{\sigma_{i}^2}$</p>
<p>where $\sigma_{i}=1/n_i$, $m_i$ is the modeled number of counts in bin $i$ and $n_i$ is the observed number (both are ... | g43285 | [
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<p>Is there a way to calibrate against multidimensional control totals using the <code>survey</code> package? I have been able to estimate poststratification weights, but now I'm stuck with the calibration. (I have a clustered design and need the weights to stay the same within each cluster.) Do I have to recode all co... | g58916 | [
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<p>I'm using libsvm in C-SVC mode (-s= 0) with linear kernel (-t= 0), and I'm required to train multiple SVMs( I have four classes).</p>
<p>My training and test sets have the same number of instances and features, they have 32768 instances (rows) and 128 features(columns).</p>
<p>I used five different C values which ... | g58917 | [
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<p>What is a sound methodology to improve the efficiency of the regression coefficients when we are interested in predicting the <em>larger values</em> of the marginal distribution (tails)? </p>
<p>For example, we want to predict seismic waves based on a number of covariates recorded by our probes. Data can not be ass... | g58918 | [
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<p>I kinda heard that usual coins are not exactly fair.</p>
<p>The experiment done way ago and one done relative recently could reject the null</p>
<p>hypothesis of p=1/2 after maybe hundreds of thousands of coin tossing!</p>
<p>And I heard the probability of dice is not fair either.</p>
<p>The obvious reason is th... | g58919 | [
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<p>I have a data set that consists of counts of striae (lines) on fish teeth. I want to assess within observer and between observer error for my data, and compare values to published counts of the same teeth. I had three observers (Alex, Clair, and Kate - see below) each take repeated counts of each tooth to capture wi... | g58920 | [
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<p>Can someone summarize for me with possible examples, at what situations increasing the training data improves the overall system?
When do we detect that adding more training data could possibly over-fit data and not give good accuracies on the test data? </p>
<p>This is a very non-specific question, but if you wan... | g58921 | [
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<p>Lately I've been reading a lot about time series clustering as I want to search for similar patterns in my own data set. Even though I feel like I understand the basic concepts of this task I still get confused when talking about high dimensional- as well as multivariate time series. </p>
<p>While multivariate time... | g58922 | [
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<p>Mantel's tests are commonly used to compare genetic distances (say, between a number of individuals) with true or hypothesized landscape distances between those same individuals. For example, “does simple linear distance better correlate with observed genetic distance than a distance based on avoiding some landscape... | g14211 | [
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0.014... |
<p>I wonder if someone could help me with the interpretation of the "z-scores" (%IncMSE) in the random forest approach. I am using a randomForest library in R. Specifically, I am not sure whether the sign of the score (-/+) can be possibly interpreted as a direction of the effect of a predictor on the outcome variable?... | g58923 | [
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0.0... |
<p>I need to compare the accuracy of time series modeling and neural network techniques. As we all know, large data set is needed for neural networks. Since I'm comparing both techniques, I have to consider equal size for both. I have 5 years of daily exchange rates for the analysis. </p>
<p>Time series plot of 5 year... | g58924 | [
0.017020927742123604,
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<p>I have 1400 cases (students) . I want to predict who goes onto University based on percentage scores of subjects taken.
Not all students took the same subjects, nor the same number of subjects.<br>
My data has NA as the percentage in the subject column if they did not take a subject, otherwise I have a value from ... | g14214 | [
0.0048754457384347916,
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<p>I try to implement logistic regression with auto-correcting learning rate and I am puzzled by the outcome.</p>
<p>At some point the cost of the function gets bigger than previously (to focus on some numbers let's say 628, when previously was 78). So I undo this step and at the same time decrease the learning rate f... | g7838 | [
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<p>My question relates to a real research problem I am having. I am going to do EFA (well actually PCA) on a 111 item questionnaire designed to screen for 20 different disorders found in childhood and adolescence. Incidentally, I am going to use Velicer's MAP test to decide number of factors to extract. My search of th... | g112 | [
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... |
<p>My mean is <code>3.454992884900722e+008</code>, and my confidence intervals from three distributions (when compared to the given mean) are:</p>
<p><strong>CI for dist. 1:</strong> 1.0e+008 * [4.084733001497999 4.097677503988565]</p>
<p><strong>CI for dist. 2:</strong> 1.0e+008 * [5.424396063219890 5.586301025525... | g43297 | [
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0.014374077320098877,
0.04323137924075126... |
<p>We observe the input samples as $Z = X+Y$, where distribution of $Z$ could be estimated by histogram of samples and $X,Y$ are two independent random variables. One of the variable was known following exponential distribution (as $X \sim Exp(\lambda)$).</p>
<p>I want to get the parameter of $X$, $\lambda$, and proba... | g58925 | [
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<p>What would be a "reasonable" minimal number of observations to look for a trend over time with a linear regression? what about fitting a quadratic model?</p>
<p>I work with composite indices of inequality in health (SII,RII), and have only 4 waves of the survey, so 4 points (1997,2001,2004,2008).</p>
<p>I am not s... | g14222 | [
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<p>I've been experimenting with the <code>rfe</code> function in the <code>caret</code> package to do logistic regression with feature selection. I used the <code>lmFuncs</code> functions with the following <code>rfeContol</code> :</p>
<p><code>ctrl <- rfeControl(functions = lmFuncs,
method = '... | g58926 | [
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0.03774777799844742,
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0.005... |
<p>Does this type of chart have a name? More importantly, is there any visualization library I can use to produce it?</p>
<p><img src="http://i.stack.imgur.com/jDQjY.png" alt="alt text">
<a href="http://www.nytimes.com/interactive/2007/12/15/us/politics/DEBATE.html">http://www.nytimes.com/interactive/2007/12/15/us/pol... | g61 | [
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<p>I did an experiment with a die where I counted the number of occurrences of each value, and associated the values as an element in a set.</p>
<p>For example, here are the values I got when I rolled a die 18 times:</p>
<p>1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6</p>
<p>1 - 3 occurrences
2 - 3 occurrences
3 - 3 occurren... | g14223 | [
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<p>I require some assistance with HLM Conjoint Analysis.</p>
<p>Say a preference-survey asks multiple respondents which of three products they prefer, using different combinations of product features (each respondent answers multiple times with different product combinations each time). For example, a single choice ma... | g58927 | [
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<p>I understand that to calculate the probability of two independent events both happening, one can simply multiply the probabilities.</p>
<p>However, consider the following:</p>
<p>A list of counties in the East coastal U.S. Each county has a calculated probability of a hurricane making landfall next year. I am tryi... | g14226 | [
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<p>I was wondering what happens to bias and variance of GLM estimates as dimensionality approaches the number of training data points? Specifically in Linear Regression and Poisson Regression?</p>
<p>I know for Logistic Regression there is the Hauck-Donner phenomenon, which increases separation in the data, and increa... | g43306 | [
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<p>Suppose you're renowned statistician down on his luck, for whatever reason, and only has $100 to live on for the next week.</p>
<p>Suppose next, someone offers you a game by flipping a coin (no gimmicks with coin) and offers to give you 150 dollars if it lands on heads and take your 100 dollars if it lands on tails... | g14227 | [
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<p>I am interested in non-parametric methods for building confidence intervals for an estimator (e.g. the mean) using few samples (e.g. 10). I think I have read somewhere that smoothing the bootstrapped estimator values can improve the quality of the derived percentiles interval. However I could not find any online ref... | g58928 | [
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-0.0029969741590321064,
-0.017920706421136856,
-0.00546086672693491,
-0.018385546281933784,
0.06131364777684212,
0.018621906638145447,
-0.06656195223331451,
-0.0411563515663147,
-0.003980336245149374,
-0.004249001387506723,
0.05835361406207085,
... |
<p>I want to find the similarity factor (some numerical value) between two variables.</p>
<p>Example:</p>
<p>row 1: 5.1, 3.5, 1.4, 0.2</p>
<p>rows 2: 4.9, 3.1, 1.5, 0.1</p>
<p>How to find similarity factor between these two variables?</p>
<p>There is correlation but other than that what are the options? </p>
<p>T... | g58929 | [
0.06279437988996506,
-0.016454216092824936,
-0.0040548196993768215,
-0.047620974481105804,
0.014556321315467358,
-0.011363212019205093,
0.03224853426218033,
-0.043102916330099106,
-0.038521599024534225,
-0.035402875393629074,
0.008033420890569687,
0.051100652664899826,
0.010503514669835567,
... |
<p>I was wondering what the theoretical difference is between the Wilcoxon Rank-Sum Test and the Wilcoxon Signed-Rank Test using paired observations. I know that the Wilcoxon Rank-Sum Test allows for different amount of observations in two different samples, whereas the Signed-Rank test for paired samples does not allo... | g58930 | [
-0.013733483850955963,
0.004687190987169743,
0.020297270268201828,
-0.02276332676410675,
0.021490972489118576,
-0.03583962470293045,
0.02437467686831951,
0.04391118511557579,
0.02863144315779209,
-0.03872048109769821,
0.00850582029670477,
0.05951724201440811,
-0.008429142646491528,
-0.0029... |
<p>So, [Wikipedia says] that the standard definition of independence is:</p>
<p>$f_{X,Y}(x,y) = f_X(x) f_Y(y)$</p>
<p>How is this applied to timeseries? How do we calculate each side of the equation? </p>
<p>If we're assuming that the probability distributions of the two series are the same, then $X=Y$ and we can ju... | g14232 | [
0.03641015663743019,
0.03212284669280052,
-0.018867935985326767,
0.013054593466222286,
-0.006830625701695681,
-0.022256001830101013,
-0.024488262832164764,
0.025182699784636497,
0.010653738863766193,
-0.002792992163449526,
-0.06820196658372879,
0.021469729021191597,
0.03418518230319023,
0.... |
<p>I have 2 possible ways to mean center.</p>
<ol>
<li>Take the mean of the training data only, and center both test and training data using it. </li>
<li>Take the mean of combined test and training data, and center both test and training data using it.</li>
</ol>
<p>Which one is correct?</p> | g58931 | [
0.02843802608549595,
-0.014866076409816742,
0.016902266070246696,
-0.054083678871393204,
0.05970354378223419,
-0.010595066472887993,
-0.0032026036642491817,
0.03439607471227646,
0.02374453842639923,
-0.02811151184141636,
0.023671183735132217,
0.0426468551158905,
0.05850185081362724,
-0.019... |
<p>I have created cognitive summary scores from a battery of 17 neuropsychological measures. I standardized the raw scores of my patient group to the mean and standard deviation of a matched healthy control group and then averaged these standardized scores to create a composite score. The resulting composite scores w... | g14238 | [
-0.01651105284690857,
0.006651477422565222,
-0.002102318685501814,
-0.05726485699415207,
0.023822609335184097,
0.026363633573055267,
0.03643319755792618,
0.05532882735133171,
-0.005749856121838093,
-0.02891498990356922,
0.0379696823656559,
-0.06802727282047272,
0.018457287922501564,
-0.000... |
<p>What causes the different results below? </p>
<pre><code>var1 = c(0.04875,0.13725,0.28350,0.50975,0.77425,0.94700,0.05325,0.14050,0.29725,0.51525,0.79000,0.95400,0.04625,0.15250,0.29000,0.53300,0.79825,0.95225,0.05025,0.14625,0.28800,0.52625,0.78200,0.95925,0.04700,0.14225,0.30325,0.53500,0.79325,0.95875,0.04775,0... | g49349 | [
0.00815125647932291,
-0.080500528216362,
0.010020091198384762,
-0.04068264737725258,
0.12634330987930298,
0.010272056795656681,
0.11134041845798492,
-0.05109517276287079,
0.01916510798037052,
-0.007372073829174042,
-0.08117710053920746,
0.06586941331624985,
0.035468894988298416,
-0.0293948... |
<p>I performed a meta-analysis with 5 RCTs measuring odds ratios of event rates in patients receiving and not receiving a treatment. P of the pooled data resulted > 0.05; this result is acceptable for me. </p>
<p>What is the best way to deal with publication bias? I initially used the Begg test but this method is kno... | g14241 | [
0.01735541597008705,
-0.02672063559293747,
0.006041212473064661,
-0.02762356400489807,
0.033939044922590256,
-0.015265600755810738,
0.021101197227835655,
0.013253663666546345,
0.04337440803647041,
-0.023065613582730293,
0.05416670814156532,
-0.016153153032064438,
0.02184961549937725,
0.001... |
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