question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Say we have the following model:
$$Y_i = \alpha + u_{j(i)} + \epsilon_i$$ for $i=1,\ldots,m$, for some groups $j=1,\ldots,J$, and
$$Y_i = \alpha + \epsilon_i$$ for $i=m+1,\ldots,n$, where $J<m<n$. Here $u_j\stackrel{iid}{\sim}N(0,\sigma_u^2)$ and, independently, $\epsilon_i\stackrel{iid}{\sim}N(0,\sigma_\eps... | g61179 | [
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<p>I have been used to using JMP to generate custom designs for a little bit and wanted to explore generating designs with R using the DoE.wrapper packages. I wanted to generate a design that had one categorical factor (3 levels) and then one continuous factor that ranged between 10 and 100. When I looked at the docu... | g61180 | [
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<p>I'm given the following question about conditional independence:</p>
<p>"Suppose we have four random variables a, b, c, d. Prove that, if a is conditionally independent of b and c given d, then a is conditionally independent of b given d."</p>
<p>To me, that implies the following:</p>
<p>"prove that if a|b,c,d = ... | g61181 | [
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<p>Much has been written on the ICC and Kappa, but there seems to be disagreement on the best measures to consider.</p>
<p>My purpose is to identify some measure which shows whether there was agreement between respondents an interviewee administered questionnaire. 17 people gave ratings of 0-5 to a defined list of it... | g61182 | [
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<p>I have distributions from two different data sets and I would like to
measure how similar their distributions (in terms of their bin
frequencies) are. In other words, I am not interested in the correlation of
data point sequences but rather in the their distributional properties with respect to similarity. Currentl... | g61183 | [
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<p>I have often found in practice, using nonlinear regression techniques such as feedforward neural nets or random forests, that the resulting actual-vs-fitted plot (on training set) seems obviously sub-optimal, eg. like this: </p>
<p><img src="http://i.stack.imgur.com/rxv12.png" alt="problematic actual vs. fitted plo... | g61184 | [
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<p>I have the following regression equation, where $Y^*$ is wages:</p>
<p>$$Y^* = \beta_0 + \beta_1 X_1 + \beta_2 X_1^2 + \beta_3 X_1^3 + \beta_4 X_1^4$$</p>
<p>I have been given the Beta values as, $(1.6 , 0.2 , -0.3 , 0.04 , -0.002)$, respectively.</p>
<p>I create a new variable $W$, </p>
<p>$$W=\begin{cases... | g61185 | [
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<p>I have implemented linear regression manually, for learning purposes, and I use the <a href="http://archive.ics.uci.edu/ml/datasets/Auto+MPG" rel="nofollow">"Auto MPG" data set</a> as the toy data I'm applying it to.</p>
<p>It occured to me that I don't know how to test the efficiency of my model! With classificati... | g61186 | [
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<p>I don't know exactly how to describe what I'm looking for, but I will try to make some examples. Let's take three different data series:</p>
<ul>
<li>Series A: 1,2,3,4,5,6,7,8,9,10,9,8,7,6,5,4,3,2,1</li>
<li>Series B: 1,2,1,2,1,2,1,2,1,2,1,2,1,2,1</li>
<li>Series C: 1,2,3,2,1,2,3,2,1,2,3,2,1</li>
</ul>
<p>The chan... | g17672 | [
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<p>Let's aim for some at an introductory level, some articles and some textbooks. Applied is more helpful, including R code is great. Thanks!</p> | g47397 | [
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<p>I am doing text classification, and have been playing around with different classifiers. However I have a pretty basic question: what if a new unseen document comes in and it happens to not belong to any of the pre-existing classes? The classifiers that I have seen (in WEKA, libsvm etc.) still go ahead and put the u... | g61187 | [
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<p>I have data from an experiment. The independent variable is time, the dependent variable is mass loss of organic matter. Now I want to compare whether a linear or a non-linear model fits better. From my understanding the $R^2$ (adjusted or not) should not be used and instead I should go for pseudo-$R^2$ measures (e.... | g47399 | [
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<p>This is a vague question. I will do my best, I think it has definite answers. I am hoping for answers of the form "Read book x, learn this specific topic, read this paper/s".</p>
<p>What is bothering me is that every AI system I have read about seems to have an internal model which is set up to operate in a specifi... | g17673 | [
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<p>I need to forecast a large set of values given a bell curve where a small set of given points define the contraints of the curve between -1 & 0. HELP! Eventually i will be coding this in javascript.</p>
<p>Specifically, i am forecasting sales. I know what the approximate total sales will be for each of the f... | g688 | [
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<p>The latest general framework I know in MCMC-based wrapper method(doing variable selection and clustering simultaneously) are the paper "Bayesian variable selection in clustering high-dimensional data" of Tadesse et al.(2005) and the paper "Variable selection in clustering via Dirichlet process mixture models" of Kim... | g61188 | [
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<p>I understand that SPSS can create a contingency table, and at the same time perform the chi-square test. </p>
<p>However, is it possible that when we already have the contingency table, to have SPSS do the chi-square test?</p> | g61189 | [
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<p>I am trying to determine if a given noise from a compass sensor is time-correlated (it is supposed to be!) and for that I tried to compute the cross correlation between the noise signal and the time of sampling using Matlab xcorr() function. However, I am getting a random value indicating that it is not time-correla... | g47403 | [
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<p>An increase in the number of cases and deaths occurs during epidemics (sudden increase in numbers) due to a virus circulation (like West Nile Virus in USA in 2002) or decreasing resistance of people or contamination of food or water or increase in the number of mosquitoes.
These epidemics will present as outliers w... | g17676 | [
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<p>I have two different columns of data which are recorded in different configurations and <strong>I want to show the users that these two records varie</strong> (data is time in seconds). The dataset is not of the same size as shown below. The end users are all experienced people in stats and math. My question is how... | g61190 | [
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<p>I think typical bioinformatician will keep a bunch of database files on their computers, so what are they? And how do they normally use (access) them? </p> | g9778 | [
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<p>A usual test of significance when looking a two populations is the t-test, paired t-test if possible. This assumes that the distribution is normal.</p>
<p>Are there similar simplifying assumptions that produce a significance test for a time series? Specifically we have two fairly small populations of mice that are ... | g17678 | [
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<p>I have a ground truth list, call it A, and I have different methods for generating lists that should be somewhat similar..
I want to decide which method of these generates a list that is most similar to the ground truth.. The list consists of strings..</p>
<p>I am new to these stuff, I tried average precision and ... | g17680 | [
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<p>I have the following experimental design (random block design). Block with 4 Treatments (A, B, C, D) repeated at 4 different sites. Treatments were applied to individuals of different species (factor with 6 levels), response Variable ist the heigth of an individual. Main focus is on the effect of the treatment, but ... | g61191 | [
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<p>I have an extremely large data set, but I'll simplify it down as, although I think I should use a chi squared test, I've run into difficulties applying it:</p>
<p>Let's say I have a list of 20 different 'foos'.The number of 'foos' that bind 'bars' has a normal frequency distribution.
Some 'Foos' bind to various 'b... | g61192 | [
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<p>We are trying to test the hypothesis that a mild mutation of a gene has few effects on the expression of the transcriptome than complete deletion. Further we wish to test the hypothesis that the genes altered by the both the mutation and the deletion affect a particular process. We have two color spotted microarray ... | g61193 | [
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<p>I made 100 measurements of a certain quantity, calculated mean and standard deviation (with MySQL), and got mean=0.58, SD=0.34.</p>
<p>The std seemed too high relative to the mean, so I made 1000 measurements. This time I got mean=0.572, SD=0.33.</p>
<p>I got frustrated by the high standard deviation, so I made 10... | g49377 | [
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<p>I try to understand user characterization from twitter data. How can I understand the user's interest from statuses? From my researches, LDA(Latent Dirichlet Allocation)suitable for topic extraction. I've collected data, remove stop words, punc. so far But I didn't have any train data or any example topics. Should I... | g17687 | [
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<p>My plain regression looks as follows:</p>
<p>tendaystockreturn = alpha + beta * dummy variable that takes a value of 1 in case a director purchases shares</p>
<p>Now I want to test whether a subgroup of directors will have a higher beta. In other words, I want to know whether the beta of a subgroup differs from th... | g61194 | [
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<p>I am trying to calculate if there is a dependence between two categorical columns, or a significant cooccurence of two categorical variables. Let's say I have columns A and B, and and out of 200K rows A is '1' 13683 and B is '1' 35171 times. Out of this, 2871 rows have both A and B '1' at the same time. </p>
<p>Ho... | g61195 | [
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<p>I have computed a truncated normal distribution, which total probability density (i.e. area under the curve) is equal to 0.92. </p>
<p>The distribution represents well the reality of the phenomenon I am investigating, i.e. I am expecting that when x = 0 the probability will be positive (non-zero). The mode is also ... | g17690 | [
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<p>I want to do document classification by representing each document as a set of features. I know that there are many ways: BOW, TFIDF, ... </p>
<p>I want to use Latent Dirichlet Allocation (LDA) to extract the topic keywords of EACH SINGLE document. the document is represented by these topic words. But I do not know... | g61196 | [
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-0.01116094645112753,
-0.011954923160374165,
0.020131908357143402,
0.... |
<p>I have difficulties interpreting an interaction term in a linear regression with regards to my hypothesis.</p>
<p>Consider this basic example:</p>
<blockquote>
<p>H0: Better school grades lead to higher income and this
relation is the same for men and for women.</p>
</blockquote>
<p>DV: income</p>
<p>IV: sch... | g17693 | [
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<p>Can any one help me please with this problem ::</p>
<p>I would like to know the distribution of the following :</p>
<p>$|h' G(G'G)^{-1}|^2$ or $(G'G)^{-1}Ghh'G(G'G)^{-1}$
where $h$ is a Gaussian vector and $G$ is a Gaussian matrix and they are independent.</p>
<p>It is related to Zero forcing technique .</p> | g17694 | [
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<p>I am testing for difference several different groups, i.e.</p>
<blockquote>
<p><strong>A</strong> vs <strong>B</strong></p>
<p><strong>C</strong> vs <strong>D</strong></p>
</blockquote>
<p>Is it okay to run multiple t-test, one for each couple, since no group is tested twice?</p>
<p>Thank you <em>very very... | g61197 | [
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<p>I am doing a time series analysis on a quarterly basis from 1990 to the third quarter 2012. Some of the time series had a drop in 2008 because of recession then resumed upwards. This drop is rather steep. I am thinking of using credit spreads since credit spreads follows the economy rather well. Then I can apply c... | g61198 | [
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<p>I've seen a fair few of these posts already, and I feel a bit silly for posting yet another question on the topic - but I just cant seem to get my head around it. I'm very new to R and esp new to lme, so bear with me.</p>
<p>My study is on behavioural traits in fish, where I have 'sampled' 49 fish over a 3 month pe... | g38627 | [
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0.02419... |
<p>I wanted to see the impact of small business support programs on small business growth. I regressed their growth (represented by the number of employees) on only those 5 kinds of support programs (as regressors). and I found R squared= 0.35, adjusted R squared= -0.03, some coefficients are positive while some others... | g61199 | [
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-0.05366641655564308,
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0.008... |
<p>(topic moved from <a href="http://math.stackexchange.com/questions/173984/posterior-parameter-distribution-for-multinomial-after-sampling">maths.stackexchange.com</a>)</p>
<p>I'm currently developing an application integrating a probabilistic inference engine for Bayesian Networks. The Bayesian Network integrates s... | g34873 | [
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<p>I was trying to model the relationship between utilization of service (from 0 to 1) and travel distance. First I binned travel distance by each 20 km and then calculate utilization for each bin (count of people utilized service/total count of people in this bin). Hypothesis is that utilization would decrease as trav... | g61200 | [
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<p>I have the data as below, I wonder how to describe it correctly.</p>
<p>The limitation of detectable concentration is 0.375, so, sample 3, concentration at d0 and d6 was undetected. How can I describe the concentration at d0, d6 when I want to reflect the evolution of concentration by time?</p>
<p>Some suggested t... | g61201 | [
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<p>I have split my data into two parts. I have used my 80% data to build a multiple regression linear model. Now I want to test it using my rest 20% data. What tools on Minitab do I have to make this checking process?</p>
<p>Edit: I think I can use PRESS statistic. My PRESS for 80% data was 6000 and now based on this ... | g17695 | [
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<p>I have a Likert scale questionnaire with 9 attributes of a system (such as stability, security, cost, etc...) For each of the attributes, the respondents can answer how much the attribute is important to them on a scale Strongly agree, Mostly agree, Neither agree nor disagree, Mostly disagree and Strongly disagree. ... | g61202 | [
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0.040516313165426254,
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0.005... |
<p>I have 100 samples from a normal distribution with variance equal to 1, and mean equal to 0. I have selected 90 samples randomly out of the 100 and i have estimated their mean (the average of the 90 samples), based on the assumption that the variance is the same as that of the original sample.</p>
<p>My question is... | g2627 | [
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... |
<p><strong>Short version:</strong> <i>is there an introduction to Ronald Fisher's </i>writings<i> (papers and books) on statistics that is aimed at those with little or no background in statistics?</i> I'm thinking of something like an "annotated Fisher reader" aimed at non-statisticians.</p>
<p>I spell out the motiv... | g17697 | [
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0.0... |
<p>I'm conducting the analysis on readmission rate for a hospital unit between 2009 and 2012. I have a list of "historical" data where patients did not have the intervention. I then have a different set of patients who did get the intervention.</p>
<p>My question is, is it enough to consider the historical dataset as ... | g61203 | [
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<p>Say for example I had a weighted graph such that each node had an associated value. The nodes' values are given by some function of the edge weights and the number of edges as well as the node's coordinates. There is no upper limit to the number of potential edges any one node can have. Relationships can be linear/l... | g61204 | [
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0.05556238070130348,
... |
<p>I'm running a logistic regression (N = 15000) and the percentage accuracy in classification (sensitivity) of the model with predictors included = 0 (the SAME as the constant model without predictors). Meanwhile the specificity remains unchanged from the constant model to the model with predictors (both 100%). </p>
... | g17701 | [
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0.044099096208810806,
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... |
<p>I am used with linear models. I can see rising use of kernel based method particularly in machine learning. </p>
<p>The following is an example Gaussian kernel using <code>gausspr</code> function from the R package <code>kernlab</code>. The function is an implementation of Gaussian processes for classification and ... | g17702 | [
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<p>I was reading an article on a power analysis and sample size calculations for a class of models that known as joint longitudianl-survival models. The paper derives a closed form formula for power and sample size calculation. Paper is a frequentist paper in a sense that it assumes parametric assumptions and based on ... | g61205 | [
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<p>When conducting an intervention analysis with time series data (aka Interrupted Time series) as discussed <a href="http://stats.stackexchange.com/questions/108374/arima-intervention-transfer-function-how-to-visualize-the-effect">here for example</a> one requirement I have is to estimate the total gain (or loss) due ... | g61206 | [
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<p>I'm trying to create a regression model for a dynamic pricing system that looks to maximize revenue. The problem that I'm having is that the system in place before (which is the source of my data) involved the owner deciding where to price things based on his own personal expectations of demand. Thus, when trying to... | g61207 | [
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0.... |
<p>I would like to use Good-Turing smoothing to find the probability of the next type of fish I will catch. If I have caught the following already:</p>
<pre><code>1 carp, 1 perch, 1 whitefish, 1 trout
</code></pre>
<p>Then N1 = 4, since I have seen four types of fish one time. </p>
<p>I know that with Good-Turing th... | g61208 | [
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<p>My project involves 1) Comparison of new samples against a control and 2) Find any effect on the speed of growth and germination % of seeds by treating them with the new samples</p>
<p>My question is, what kind of statistical analysis to carry out and an explanation on why to use that specific test.</p>
<p>I have ... | g61209 | [
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<p>I've been running some power simulations for a one-way ANOVA in R, and my problem is that the results from the simulation doesn't match the result from g*power or <em>pwr.anova.test</em> from the "pwr"-package. As an example, let's compare simulated power to analytical power using these values:</p>
<pre><code>group... | g61210 | [
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-0.06364408880472183,
0.021982964128255844,
0.048292871564626694,
0.028706258162856102,
0.0026736003346741... |
<p>I have list of proteins with their feature values. A sample table looks like this:</p>
<pre><code>...............Feature1...Feature2...Feature3...Feature4
Protein1
Protein2
Protein3
Protein4
</code></pre>
<p>Rows are proteins and columns are features. </p>
<p>I also have a list of proteins which intera... | g17706 | [
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0.03404557332396507,
0.04179326072335243,
0.0721... |
<p>Suppose we want to cluster a data stream of unknown number of clusters, and estimate them using particle filters. With particle filters, we need to know $P(x_t | x_{t-1})$ and $P(z_t | x_t)$ (where z refer to the data (reports), and x refer to the estimated states (hypothesis)).</p>
<p>Then my question is: how can ... | g61211 | [
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0.001991698984056711,
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0.05123632773756981,
0.11211458593606949,
-0.00... |
<p>I just estimated the parameters for a mixture of two gaussians with different means and different sigmas, I would like to test if the data adjusts well to the explicit form of the mixture, do I necessarily need to simulate data from the mixture or how can I test the goodness of fit? I am using the mixtools package.<... | g49614 | [
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<p>I want to know how random variables at a certain geographic location are correlated spatially. Lets say I have a certain function z depending on the spatial locations of the points. If I plot this z values spatially, then from the plot how can I analyze their spatial correlation. How does the plot look like or suppo... | g17708 | [
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<p>I'm trying to describe mean differences between two populations $x_1$ and $x_2$, which are non-zero and positive. Their distribution is approximately beta with a positive skew. For example, with R:</p>
<pre><code># x1 <- round(rbeta(10, 1, 100)*1000, 1)
# x2 <- x1 + round(rbeta(10, 1, 100)*100, 1)
x1 <- c(... | g48949 | [
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0.015121012926101685,
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0... |
<p>I am looking for some libraries in R that can do incremental learning (also called online or sequential learning). The use case of such learning in comparison to traditional batch methods would be to process large amounts of data. Such practices include streams and data from sensors, where it is not feasible to use ... | g17710 | [
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<p>I am currently self-studying statistics and I'm confused about the null model in binary logistic regression. I understand that the null model is used to be compared with the model you designed, but what exactly is the null model? Just ln(x)=y?</p> | g61212 | [
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<p>In a graphical model, two random variables are conditional independent given their common ancestors.</p>
<p>Can graphical models represent independence besides conditional independence?</p> | g61213 | [
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<p>After some amazing help, especially from @jbowman, I was ready to get into my models but have hit a snag that I don't understand.
I decided to try package MuMIn as it works with lme4 so that I am able to do all the models in once shot rather than running them each one at a time. However apart from loading it and the... | g17712 | [
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0.... |
<p>I have an unbalanced panel data set of 40 cities and 20 years. It is unbalanced because the data are not collected for certain cities for every year. The data are then balanced after these 20 years.</p>
<p>Suppose the time periods are 1960 to 1979 and then 1980 to 1999. I want to compare the data for 1979 with t... | g61214 | [
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<p>If there are $n$ samples $X_1 \leq X_2 \leq ... \leq X_n$ from a continuous uniform distribution with pdf $f(x)=\frac{1}{\theta},0\leq x \leq \theta$,
then it is well known that the MLE for $\theta$ is $\hat{\theta}=X_n$.</p>
<p>However, if the bootstrap is used to estimate the confidence interval of $\hat{\theta... | g61215 | [
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<p>Using sparse matrix objects in svm training in e1071 returns different results than running on the same data represented as standard matrix:</p>
<pre><code>library(e1071)
library(Matrix)
library(SparseM)
m=10
n=800
#means <- colMeans(myData)
#stdDevs <- apply(myData, 2, sd)
means <- c(0.042154664, 0.010474... | g17713 | [
-0.012649673968553543,
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0.02071896754205227,
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0.04419331252574921,
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0.06621243804693222,
0.02171219140291214,
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-0.028287921100854874,
0.008613280951976776,
0.009872299619019032,
0.03734065964818001,
0.0184... |
<p>I have 2 groups: N=350 (G1) and N=1,500(G2). G1 refers to 1 company and G2 is a group of 4 companies.
Is z test appropriate to test the significant differences between percentage distribution?, i.e. if 51/49% male/female in G1 is significantly different than 46%/54% male/female in G2?
Thanks!</p> | g17714 | [
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0... |
<p>When using a mixed model to analyze some data, is it common to report the variance estimates of the random effects in a publication, for example for a medical journal? </p>
<p>I don't see how this information would be of interest to the reader and therefore was not sure if we should include it. If yes, should we al... | g17715 | [
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<p>My correlation matrix is not showing very high correlations (less than 0.5), but still, when I am regressing panel fixed effects models, all my variables are omitted, and it shows it is due to collinearity among the variables. What is the way out of it?</p> | g61216 | [
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<p>I am creating a program to collect and analyze prices for goods and alert the user when the price decreases so that they can buy it on "sale." I know a little statistics (e.g. standard deviation) but am looking for the best way to determine if a price drop is significant compared to historical prices - i.e. if I sho... | g61217 | [
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0.0014016445493325591,
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... |
<p>I'm investigating interplay between two variables ($x_1$ and $x_2$). There is a great deal of linear correlation between these variables with $r>0.9$. From the nature of the problem I cannot say anything about the causation (whether $x_1$ causes $x_2$ or the other way around). I would like to study deviations fro... | g17721 | [
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<p>I am not able to find an existing name for the comparison function I wrote.</p>
<p>I have two lists of values which I want to compare. At first I used jaccard, but then I recognized I need to eliminate the length of the second list as it does not seem to have anything to say in my use-case. So I changed jaccard to:... | g61218 | [
0.06733518838882446,
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0.021453311666846275,
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0.04... |
<p>I am trying to use neural network to learn a non linear function mapping input to outputs. However, I am having some issues with it. I used tansig activation function for the hidden layers and for the output I used logsig. I scaled the output variables in the range [0 1]. The input variables were standardized to zer... | g61219 | [
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<p>I am trying to evaluate the effect of an intervention. I have a group-randomised rct design and have established that I have a design effect and therefore need to control for school. So far I have managed to restructure my data so that it is now vertical and I have a variable called 'time' which represents my pre an... | g61220 | [
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<p>I commonly calculate the precision and recall for information pulled from text but I'm not sure how to calculate the margin of error for those precision and recall values.</p>
<p>So for example, if I have a sample 1,000 given names out of an unknown amount of data. My goal is to indentify the gender of of each name... | g61221 | [
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<p>This is a pretty general question regarding observations versus modelization and how to obtain the modeled set that best fits/reproduces an observed set of objects.</p>
<p>I have a given set made of observed/measured objects which I call set $O$. The are $N$ objects in $O$ ($n_1$, $n_2$, ..., $n_N$) and each one is... | g17727 | [
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<p>I've got a completely randomized block design with three treatments and four replications. Biodiversity was measured in four successive years.</p>
<p>I figured that a mixed model with repeated measures as random terms should be appropriate to analyse this design.</p>
<p>My hypothesis is that considering all years,... | g61222 | [
0.01847732998430729,
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0.0250... |
<p>Suppose you are measuring temperature $T_{ij}$ for $i =1, \dots ,4$ subjects and $j= 1, \dots ,4$ time points. For subject 1, suppose $T_{12}$ and $T_{14}$ were missing. Would you omit the entire record for subject 1 if you are running a linear mixed model?</p> | g17730 | [
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<p>I would like to learn simultaneously $k$ linear maps $\{\phi_0, \dots ,\phi_{k-1} \}$ at the same time:</p>
<p>$min \sum_{i=0}^{k-1} \sum_{j=i+1}^{k-1}||X_i \phi_i - X_j \phi_j||_2^{2}$,</p>
<p>such that $||X_{ij} \phi_i||_2^2 = 1$ (rotated row vector)</p>
<p>given the data ${X_i, X_j} \in \mathbb{R}^{m\times n}... | g223 | [
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<p>Some research shows that female politicians put forward a more diverse issue platform than male politicians--meaning they discussion greater variety of issues than men. I would like to see whether this is occurring in my study. </p>
<p>I conducted a content analysis of candidates tweets, and used those percentages ... | g61223 | [
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0.028038479387760162,
0.03692452237010002,
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0.07... |
<p>The Department has an online system whereby students can voluntary sign up to take part in lab studies to earn credits towards their coursework. Students have to check this online system frequently to see if they are interested in participating in any of the listed studies. Also they visit that online system to regi... | g61224 | [
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<p>I've checked two textbooks about EFA, one is the seminal work of Gorsuch (1974, 'Factor Analysis') and the other 'Exploratory and Confirmatory Factor Analysis' by Thompson (2004). Both described <strong>determination of number of factors</strong> to be extracted as a stage before choosing <strong>factor extraction m... | g61225 | [
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0.03991556167602539,
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0.0573076494038105,
0.0209... |
<p>A simple random sample of size $n=n_1 + n_2$ is drawn without replacement from a finite population of size $N$. Further a simple random sample of size $n_1$ is drawn without replacement from the first sample.
Let $\bar y$ and $\bar {y_1}$ be the respective sample means.</p>
<p>Find V($\bar {y_1}$) and V ($\bar {y_2... | g61226 | [
0.013904821127653122,
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0.0003453790850471705,
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0.006702431943267584,
-0.032396458089351654... |
<p>I'm studying about kernel density estimation and from <a href="http://en.wikipedia.org/wiki/Kernel_density_estimation" rel="nofollow">wikipedia</a> I get this formula: </p>
<p>$$\hat{f}_h(x, h) = \frac{1}{n}\sum^{n}_{i=1}K_h(x-x_i) = \frac{1}{nh}\sum_{i=1}^nK(\frac{x-x_i}{h}).$$</p>
<p>I think I've got the basic i... | g61227 | [
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0.04090587... |
<p>How do you know when to use AIC or BIC for determining model fit? Is it just a judgment call? Is there an intuitive explanation as to which heuristic is better than the other?</p> | g49615 | [
0.04565857723355293,
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<p>I am using <code>glm</code> to find a model using training data and then use test data to see how well the model is behaving. My response variable is <code>numeric</code>.</p>
<p>Below is a toy example that is showing the steps taken by me:</p>
<pre><code>library(car)
summary(Prestige)
head(Prestige)
testidx <... | g61228 | [
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0.015715403482317924,
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-0... |
<p>My question is inspired by <a href="http://stats.stackexchange.com/questions/16247/calculating-the-probability-of-gene-list-overlap-between-an-rna-seq-and-a-chip-ch">this</a> post. However, its a bit more complicated than that to explain. I hope I succeed.</p>
<p>I work with RNA-Seq data on <em>alternative splicing... | g38026 | [
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0.040941011160612106,
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0.016706418246030807,
0.06691072881221771,
0.0... |
<p>I have a question as to which statistical test I need to use to accomplish this.</p>
<p>I have a population of 80 patients:</p>
<ul>
<li>37 had procedure A </li>
<li>43 had procedure B</li>
</ul>
<p>Of the 80 patients, 19 patients had recurrent disease:</p>
<ul>
<li>13 had procedure A</li>
<li>6 had procedure B<... | g61229 | [
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0.04318661987781525,
-0.0039785... |
<p>How does the stepwise regression method work for <code>both</code> direction in R with the <code>step()</code> function.</p>
<p>I would think that one variable will be placed into the model and then another that will improve the measuring criteria and the significance of the older variable gets assessed. If the old... | g61230 | [
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0.0004318426945246756,
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0.... |
<p>I have little knowledge of statistics and was wondering what tests to use for an evidence-based project (not research, so I am not using a control group) that I am conducting. </p>
<ul>
<li><p>What statistical test would I use for pre and post knowledge tests after a student educational intervention? </p></li>
<li>... | g61231 | [
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0.011041471734642982,
... |
<p>I am in great need of help in order to infer the statistical hypothesis tests performed in <em>Xanthelasmata, arcus corneae, and ischaemic vascular disease and death in general population: prospective cohort study</em>, BMJ. 2011 (see <a href="http://www.bmj.com/content/343/bmj.d5497" rel="nofollow">here</a>).</p>
... | g61232 | [
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0.000571054988540709,
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0.0011902640108019114,
0.10202211886644363,
0.019... |
<p>I was given a dataset to analyze with two factors, time and treatment, and one continuous dependent variable. Since the same individuals were measured at multiple times, technically it probably could be done as repeated measures, but the measured values I was given already represent the average of multiple measureme... | g61233 | [
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-0.014400758780539036,
0.... |
<p>The Maximum of $X_1,\dots,X_n. \sim$ i.i.d. Standardnormals converges to the <a href="http://en.wikipedia.org/wiki/Gumbel_distribution#Standard_Gumbel_distribution">Standard Gumbel</a> Distribution according to <a href="http://en.wikipedia.org/wiki/Extreme_value_theory#Univariate_theory">Extreme Value Theory</a>.</p... | g61234 | [
0.0033588730730116367,
0.05086645111441612,
-0.02638338692486286,
-0.019622690975666046,
0.0155534278601408,
0.0019034299766644835,
-0.036818038672208786,
-0.004617814905941486,
-0.023762840777635574,
0.010366501286625862,
-0.05134091526269913,
0.0010947673581540585,
0.020020747557282448,
... |
<p>What is the critical p-value used by the <code>step()</code> function in R for stepwise regression? I assume it is 0.15, but is my assumption correct? How can I change the critical p-value? </p> | g49696 | [
0.011014199815690517,
-0.043961308896541595,
-0.0030008438043296337,
-0.01294749602675438,
-0.003234313800930977,
-0.010931418277323246,
0.003683221060782671,
0.06013993173837662,
-0.05451168492436409,
-0.03557119145989418,
-0.0035952834878116846,
0.015622856095433235,
0.0413840115070343,
... |
<p>I am trying to plot an ideal ROC plot as predicted by Signal Detection Theory. </p>
<p>Here are the formulas I try to plot: </p>
<pre><code>hi = Φ((d′−ci)/σ) (3)
fi = Φ(−ci) (4) 
</code></pre>
<p>where d′ and σ are the mean and standard deviation of strength for old items, and ci is the criterial bound for the i... | g61235 | [
0.003931288607418537,
-0.05131587013602257,
-0.02883383259177208,
-0.051744699478149414,
-0.006680966354906559,
-0.040805041790008545,
0.015310822054743767,
0.021617846563458443,
-0.060857392847537994,
-0.01282641850411892,
-0.01658545434474945,
0.019549988210201263,
-0.0014436760684475303,
... |
<p>How can I make use of the information that shows confidence of that training instance? i.e. We have an extra information for training set about the confidence of class labels.</p> | g61236 | [
-0.03436317667365074,
0.01098581962287426,
0.013289833441376686,
-0.061148762702941895,
0.02176404930651188,
0.04942166432738304,
-0.017577119171619415,
0.011737087741494179,
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-0.04804207384586334,
-0.014246770180761814,
0.029304124414920807,
0.03402185067534447,
0.01... |
<p>I want to test multiple possible cointegration relationships with the Johansen cointegration test. I'm currently using the urca package in R with the ca.jo test. I was going to use the Bonferroni correction to correct the familywise error rate. However, ca.jo doesn't report p-values. It only reports test statistics ... | g61237 | [
0.0547836497426033,
-0.011282621882855892,
-0.0014922181144356728,
-0.03210172429680824,
0.007155844941735268,
-0.022032104432582855,
0.04024549573659897,
0.030705198645591736,
-0.023266838863492012,
0.009872090071439743,
-0.009908345527946949,
0.002717482391744852,
0.06282264739274979,
0.... |
<p>Assume two independent random complex vectors (with real and imaginary parts):
$$
\vec{\dot{Z}}=(\dot{z}_1,\dot{z}_2,\ldots,\dot{z}_n)~~~~~~~~~~ \begin{cases} \Re(\dot{z}_i)&=x_i \\ \Im(\dot{z}_i)&=y_i \end{cases}\\
\text{and} \\
\vec{\dot{\zeta}}=(\dot{\zeta}_1,\dot{\zeta}_2,\ldots,\dot{\zeta}_n)~~~~~~~~~... | g17740 | [
0.02544551156461239,
-0.059173617511987686,
-0.02749946154654026,
-0.07509694248437881,
0.0047821407206356525,
-0.05107406899333,
0.024930870160460472,
-0.006810326594859362,
0.04987432807683945,
0.033290714025497437,
0.0018587593222036958,
-0.007211180869489908,
0.012838351540267467,
-0.0... |
<p>I have a question regarding the interpretation of the different matrices produced by singular value decomposition.</p>
<p>Suppose a mxn matrix $A$ containing n images of m pixels. So each column of this matrix when reshaped is an image. The images are actually wavelets transformations but that bears no relevance to... | g61238 | [
-0.026065697893500328,
-0.0075460984371602535,
-0.013805682770907879,
-0.012065269984304905,
0.024114977568387985,
-0.034946173429489136,
0.021229716017842293,
0.04857391491532326,
-0.029553718864917755,
-0.030952246859669685,
-0.001368438359349966,
-0.005449179094284773,
0.09598573297262192... |
<p>Normally in multivariate decision trees, we can use all attributes in an internal node. Bivariate tree is a case where we are allowed to use any two attributes at an internal node. What do the splits look like in such a tree? How the splitting can be achieved?</p> | g17741 | [
-0.017180711030960083,
-0.013547146692872047,
0.03271305933594704,
-0.027055609971284866,
0.009380596689879894,
-0.08019804209470749,
-0.043936070054769516,
0.04732784256339073,
-0.008743253536522388,
0.014785638079047203,
0.03529806062579155,
0.01691891811788082,
0.007897838950157166,
-0.... |
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