question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>This is a question about a seemingly illogical approach to hypothesis testing and <em>p</em>-value interpretation that I find almost universally endorsed. I’ll cite the answers at <a href="http://stats.stackexchange.com/questions/5680/can-i-trust-anova-results-for-a-non-normally-distributed-dv">Can I trust ANOVA re... | g59675 | [
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<p>Top-coded income data are often modeled with a Pareto distribution, but that is controversial. What would be wrong with declaring those values as missing and then using multiple imputation (MI) to generate values for those cases using a normal model while assigning a lower bound as is allowed in <a href="http://www... | g59676 | [
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<p>In normal multivariate regression you can leave out covariates (assuming they aren't correlated with any covariates you leave in) and the variance of covariates left out gets subsumed into the error term. </p>
<p>In survival analysis poisson models are used. In these models the variance is a function of the mean. W... | g59677 | [
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<p>I have a population that I am technically sampling without replacement using a stratified design. The resultant ratio estimator of the sample mean in any stratum $i$ is $\hat{R}_{i} = (\sum y_{i})/(\sum x_{i})$. I also know that $x_{i} \in \theta_{x,i}$ in any stratum, such that I can obtain $\hat{\theta}_{y,i} = ... | g59678 | [
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<p>I have never found a good explanation of what the ROC50 score is and how it is calculated.</p>
<p>To take an example definition found on the net:</p>
<blockquote>
<p>The ROC50 score is the area under the ROC curve, up to the first 50 false positives</p>
</blockquote>
<p>So if I understand correctly, you look at... | g59679 | [
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<p>I have a question about estimating the reliability (coefficient alpha) of a pilot scale by assessing its internal consistency. The pilot questionnaire generates ordinal data, 9 items each with 9 ordered catagories of response. The data set has 183 complete readings of the pilot scale.</p>
<p>My question is: Is i... | g41853 | [
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<p>I'm trying to model the probability of a song reaching Billboards top 10 over time.</p>
<p>My data has the columns "Day since release", "If reached top 10".
For example, [12,1] means the song hit top 10 on the 12th day since release, and [350,0] means the song has been out for 350 days and has not become a top 10 h... | g59680 | [
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<p>1) A dataset (100 samples, 10 classes, 8 chars each) was multiclassed obtaining a good accuracy with an external dataset.</p>
<p>2) The same dataset was divided in half (50 samples, 5 classes, 8 chars each) and trained as 2 classification models (like, model 1 with classes 1-5, and model 2 with classes 6-10).</p>
... | g15350 | [
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<p>I want to use PCA in this kind of situation. I have three variables:</p>
<ol>
<li>how many times something happened for user - positive integer;</li>
<li>total "power" of all happened events for user - real number, can be negative</li>
<li>percent of "successful hits" - real positive number 0 < x < 1</li>
</o... | g49568 | [
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<p>Does anyone know of a good reference that list the reasons for transforming multiple class classification problem into a set of binary sub-problems?</p>
<p>In response to comment: One reason to transform a multiple class classification problem into a set of binary sub-problems are that a binary network is usually s... | g59681 | [
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<p>Dear statistics experts,</p>
<p>I have trouble to find a sensible statistical approach to back up some very obvious (at least to my eyes) interpretation of a dataset (see descriptive plot below).</p>
<p>I measure a response to two different stimulus (Stimulus 1 and 2) at 3 different intensities (weak medium high),... | g59682 | [
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<p>I would like to know what the following example is called in mathematics: In a gymnastics competition the judges scored a competitor as 10, 8, 3, 7, 7, 9, and 8. I recall that the ending score was always calculated after they discarded the highest and lowest numbers in the group and used what was remaining to get t... | g15353 | [
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<p>I have a data set that is represented below, but much longer. How can I find if there is a statistical relationship between business category and business score?</p>
<pre><code>Business Name Business Category Business Score
Business1 Shopping 1
Business2 Eating ... | g59683 | [
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<p>Is the claim that functions of independent random variables are themselves independent, true? </p>
<p>I have seen that result often used implicitly in some proofs, for example in the proof of independence between the sample mean and the sample variance of a normal distribution, but I have not been able to find just... | g49692 | [
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<p>There seem to be too many points clustered around negative values for all the plots
And while 3 & 4 seem to have random enough patterns, 1 & 2 seems to have negatively sloped trend. </p>
<p>If these were to violate linearity and homogeneity assumption, I should stop using the regression model, correct? </p... | g59684 | [
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<p>Given a dataset of lines containing 6 wind <strong>forecast</strong> values plus 1 observed (actual) value in each like:</p>
<pre><code> FCT1 FCT2 FCT3 FCT4 FCT5 FCT6 OBSERVED
-3.17 3.51 -5.71 1.37 -0.22 -0.65 -2.38
-2.7 2.21 -0.71 2.73 -0.33 -2.62 -1.38
-1.2 3.... | g15359 | [
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<p>I'm working on a dataset with the following variables:</p>
<pre><code>Y: a boolean telling whether the subject has experienced a seizure
ID: the id of the subject
Sess: the subject's session number (a subject has been observed multiple times)
X3: numeric measurements of the subject's behavior during the session... | g15467 | [
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<p>I am trying to cluster 6 PC scores for a 1600 cases data (so its a 1600 x 6 matrix). I am using average linkage clustering technique that would be followed by a K mean clustering. The purpose of Average linkage clustering is to provide seed values for K mean clustering.</p>
<p>Would somebody explain me how to extra... | g59685 | [
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<p>The Netflix competition kicked off a plethora of competitions to develop the best methods to learn information from given datasets. These include predicting traffic flow, predicting the success of grant applications, estimating the time patients spend in the hospital, and constructing good representations of data i... | g59686 | [
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<p>Consider the following scenario: I have an auto dealership, and I want to decide whether to buy a used car. If it's a good buy, I would make a substantial amount of money of it. If it's a bad buy, I would lose a substantial amount of money. If it's neither ("nop") , I would lose a small amount of money.</p>
<p>Natu... | g59687 | [
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<p>Suppose I have some yearly observations (e.g. rates) $x_1$,$x_2$...,$x_{t-1}$. I estimate some parameter of interest as $\bar{x}_{t-1}=\frac{1}{t-1}\sum_i{x_i}$.</p>
<p>Now at year $t$, I get a new observation $x_t$, so that I can compute $\bar{x}_{t}$. </p>
<ol>
<li>How can I "decide" if I need to update my estim... | g59688 | [
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<p>I am a beginner in statistics. I have these unpublished data (cases and deaths) of a disease for 7 years (2004-2010) from 2 neighbouring states. The study was started in 2004. State 1 and State 2 received different treatments. The death rate is high in one State. I want to prove that treatment given in State 1 is su... | g59689 | [
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<p>You may find this a basic question. </p>
<p>I am trying to model a time series model problem. My understanding is that the most parsimonious model (least variables) with the best result is best because most models don't deal well with a large number of irrelevant variables and that these variables will only introdu... | g15369 | [
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<p>I wish to calculate correlation between external rating of accounts and internal ratings of the accounts in my branch. Which out of Pearson correlation or rank correlation will be better to use and why.</p> | g49569 | [
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<p>Does any body know how to run a post hoc comparison in a 2X2 ANOVA with covariate in R. multcomp package seems very nice but I could not find clear answer or example to my question with this package. Thanks so much in advance</p> | g59690 | [
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<p>The common approach for estimating the parameters of a normal distribution is to use the mean and the sample standard deviation / variance.</p>
<p>However, if there are some outliers, the median and the median deviation from the median should be much more robust, right?</p>
<p>On some data sets I tried, the normal... | g59691 | [
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<p>How must I syntax the <code>rma</code> function from <a href="http://cran.r-project.org/web/packages/metafor/index.html">metafor</a> package in order to get results in the following real-life example of a small meta-analysis?
(random-effect, summary statistic SMD)</p>
<pre><code>study, mean1, sd1, n1, mean2... | g59692 | [
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<p>I just want to confirm that I'm on the right track.</p>
<p>I need to derive an expression for b^Y1.2 that refers solely to variances and covariances (that is, only to bi-variate and mono-variate terms).</p>
<p>I have come up with the following:</p>
<p>b-hatY1.2 = (CovY1)/(Var1) - (Cov1,2/V1)*(b-hatY2.1)</p>
<p>T... | g15373 | [
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<p>I'm examining correlations in a data set with a large number of variables but small sample sizes. To get a feel for how these quantities behave, I generated some random data and looked at the distribution of correlations:</p>
<pre><code>n = 4
y = matrix(rnorm(1000 * n), 1000, n)
x = matrix(rnorm(1000 * n), 1000, n)... | g59693 | [
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<p>I've never really found any good text or examples on how to handle 'non-existent' data for inputs to any sort of classifier. I've read a lot on missing data but what can be done about data that cannot or doesn't exist in relation to multivariate inputs. I understand this is a very complex question and will vary depe... | g37794 | [
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<p>I have 2 groups of patients (control and treated) and 1 variable measured at two time moments (before and after treatment).
Using paired T test I am able to determine the mean (with 95%CI) difference in each group (at baseline and after treatment). Using split-plot ANOVA I can say that the effect of the treatment is... | g59694 | [
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0.03004656545817852,
-0.023583248257637024,
-0... |
<p>I have a sample of an unknown distribution for which I would like an estimate of the true value and the expected error on that estimator. Since the underlying distribution is not necessarily Gaussian and the sample size is small I hesitate to use mean and standard deviation. What is a reasonable estimator and an upp... | g59695 | [
0.005101561546325684,
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0.012423991225659847,
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<p>Suppose I have two different classification, e.g.</p>
<pre><code> C R
s1 c1 r2
s2 c1 r2
s3 c3 r2
...
</code></pre>
<p>Where sn are the classified samples and the columns of the matrix represent the different classifications (one called <code>R</code> - reference, the other <code>C</code> - clusteri... | g15379 | [
0.03714928776025772,
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<p>I want to perform something like streaming/online/out-of-core kmeans clustering on large data.</p>
<p>Here is simple idea:</p>
<ol>
<li><p>Break all data into N chunks.</p></li>
<li><p>Read from disk 1st chunk and calculate centroids using original kmeans algorithm.</p></li>
<li><p>Use centroid of previous chunk t... | g15380 | [
-0.02982528880238533,
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<p>In my data I want to be able to determine which set of IVs (there are 8 variables total, 4 in each set) does a better job of predicting a set a DVs (there are 4). I know I could use multivariate regression to use all DVs in the same analyses, but I don't know how to group the IVs into 2 sets. On the other hand I cou... | g59696 | [
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<p>I have a 2X2 design (2 categorical independent variables (IVs) with 2 levels each), and a single dependent variable (DV). I have 91 samples in total with these cell counts: 30, 19. 20, 22. My data for the DV is heteroscedastic across one of my IVs (the variance is 2.5 with N=50 at one level, and 1.2 with N=41 at the... | g475 | [
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<p>I've read <a href="http://www.utdallas.edu/~herve/abdi-prc-pretty.pdf" rel="nofollow">here</a> that </p>
<blockquote>
<p>When the independent variables are pairwise orthogonal, the effect of
each of them in the regression is assessed by computing the slope of
the regression between this independent variable a... | g59697 | [
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<p>I have been trying to brush up on my stats knowledge, especially in relation to Sample size determination and Statistical Power Analysis. But it seems that the more I read the more I need to read. </p>
<p>Anyway I found a tool called <a href="http://www.gpower.hhu.de/en.html" rel="nofollow">G*Power</a> which seems ... | g59698 | [
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<p>I'm currently carrying out a four-way mixed factorial ANOVA and in the process of writing up the results. I've done simple effects analysis on all the significant interactions between the factors, however I have noticed that the output doesn't include standard deviations. </p>
<p>I've had a look at past research an... | g15381 | [
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<p>I am trying to implement the coordinate descent method to solve the dual of linear SVM problem, but blocked at the stopping criterion.</p>
<p>The <strong>dual</strong> of linear SVM problem is: $$\min f(\mathbf{x}) = \frac{1}{2}\mathbf{x}^\top K \mathbf{x} - \mathbf{1}^\top\mathbf{x},\quad \mbox{s.t. } 0\le x_i\le ... | g15382 | [
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0... |
<p><strong>Scenario:</strong> </p>
<p>An email campaign where four different email designs (treatments) are sent to four different populations of equal size in an attempt to find which performs better.</p>
<p>The results returned are:</p>
<pre><code>Treatment Population Clicks
A 120 (Group 1)... | g475 | [
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0.001393695711158216,
-... |
<p>Suppose I can observe $x_1,...,x_n$ as the realization of the random variables $X_1,..,X_n$. Using $x_1,...,x_n$, I can estimate the empirical cumulative distribution function (CDF), $F_n(x)=\sum_{i=1}^n\frac{I(x_i\leq x)}{n}$. Now, with a given $\lambda$, I can transform this CDF by using the Wang transform which i... | g15383 | [
-0.024753957986831665,
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0.0307162962853908... |
<p>Can factor scores be used as dependent variables in regression?</p>
<p>Also, I want to see if demos (e.g. age, SES etc) predict performance in five different cognitive ability tasks. For each task I have the accuracy and speed of response. Would it be worthwhile attempting to run a factor analysis on these ten vari... | g49552 | [
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<p>I am trying to model disease propagation. I am considering a map separated into regions. One region is infected. There is data over time, with the number of people travelling into and out of the infected region and which region they travel to (a table of transport of individuals over the whole map). This is an O-D m... | g38174 | [
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<p>If I construct confidence intervals for a calculation based on simulating inputs rather than using error propagation formulas, would this be considered as belonging to 'Monte Carlo' methods?</p>
<p>I would have several inputs into the calculation and they would each have standard errors that I would use to generate... | g59699 | [
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<p>We have a daemon that reads in data from some sensors, and among the things it calculates (besides simply just reporting the state) is the average time it takes for the sensors to change from one value to another. It keeps a running average of 64 datapoints, and assumes that runtime is fairly constant.</p>
<p>Unfor... | g15389 | [
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<p>If $X$ and $Y$ be two i.i.d. random variables, then what should $E(X|X<Y)$ essentially look like?</p>
<p>P.S.-Is the denominator equal to $\frac12$?
(the two r.v.'s being iid serving as the motivation behind this.)</p> | g15390 | [
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... |
<p>Just curious if anyone knows why there is a tiny but definite difference between the standard deviation as calculated by the error propagation formula and the simulation. It is only a 0.2% difference and doesn't cause me any problems personally but I am curious which of the two would be considered more accurate?</p>... | g44335 | [
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<p>We are given n classes of real values. The number of elements in each class is not too high and can be different between classes. </p>
<p>We want to test whether there exist a class with significantly higher (average) values from all other classes or not. The case is somehow similar to ANOVA, but slightly different... | g59700 | [
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<p>I am making a spam filter for an assignment. One of the steps outlined in a paper that I have read indicates finding the mutual information for all the words in the text and then choosing the 500 or so with the highest MI.</p>
<p>The equation given in the paper (and elsewhere) is:</p>
<p>$MI(X_i, C) = \sum{P(X_i, ... | g59701 | [
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<p>I'm working on multiclass logistic regression model with a large number of features (<code>numFeatures</code>>100). Using a maximum likelihood estimation-based cost function and gradient, the <code>fmincg</code> algorithm solves the problem quickly... However, I am also experimenting with a different cost function a... | g59702 | [
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<p>I am running an OLS regression using dummy variables built from categorical variables. Say, race became race1, race2 and race3. I omit race1 in order to escape the dummy variable trap and run OLS and gain some coefficients for race2 and race3.</p>
<p>What would be the coefficient for race1 in the regression equatio... | g17326 | [
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0.0004180992254987359,
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0.0902932733297348,
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0.0... |
<p>I am learning about ELM (Extreme Learning Machines) and <strong>it appears</strong> to have no bias weights at the output layer.
Besides that, just to clarify, the kind of ELM I am refering to are topologically no different than 2-layer MLPs (or 3-layer if you count the input as a layer).</p>
<p>So, I am wondering ... | g59703 | [
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... |
<p>I'm trying to build a daily alert system to let me know when something unusual has happened in my analytics data that might require further investigation.</p>
<p>Right now I'm taking 7 weeks worth of data, creating an average for each day of the week (ie Average Conversion Rate for Monday). I then compare how much ... | g59704 | [
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0.06411626935005188,
0.01... |
<p>I am trying to compute a Kernel Density from high dimensional data ($n > 2$). The underlying (generative) model is assumed unknown.</p>
<p>The goal is to draw samples from this estimate, in a sense creating synthetic data akin to the underlying distribution. </p>
<p>I was hoping to use Bayesian nonparametrics f... | g59705 | [
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0.01... |
<p>After Regression, i ran the tests for serial correlation</p>
<p>Durbin-Watson d-statistic( 7, 29) = .7938438</p>
<p>. estat bgodfrey</p>
<h2>Breusch-Godfrey LM test for autocorrelation</h2>
<pre><code>lags(p) | chi2 df Prob > chi2
</code></pre>
<p>-------------+--... | g49294 | [
0.02517344057559967,
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0.0037646994460374117,
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0.03320886567234993,
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0.021207138895988464,
0.07263614982366562,
0.03303314372897148,
-0.020... |
<p>I am kind of stuck with an easy question:</p>
<p>I have two data sets with experimental data. The data sets do not have the same size. I would like to show that these data sets are possibly coming from the same experiment.</p>
<p>I tried a two-sample $t$-test; it shows that the data are significantly different. Is... | g59706 | [
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<p>I'm using SPSS and I'm having touble with deciding what statistical method should be used: there are 3 groups with different participants and treatments and they were measured in three different experimental conditions, but one of the variables is binary (another one is continuous, derived data). Should I use glmm o... | g59707 | [
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<p>I am applying logistic regression and I am using a mixture of continuous and binary features.
My question would be how do you go about binary features when trying to normalize.
I would very much appreciate any help.</p> | g15400 | [
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<p>I'm currently trying to incorporate model errors into a likelihood function to fit the model to some results. Let's just call them $x_{m,i}$ for the model and $x_{o,i}$ for the $N$ observations, indexed by $i$.</p>
<p>Each observation has a given Guassian/normally-distributed error $\sigma_{o,i}$. For the model, ... | g15403 | [
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<p>The problem is how best to analyse data which involves multiple dependent measures, taken on multiple/repeated occasions and determine whether there's a difference between two groups.</p>
<p>I'm trying to analyse data from a study involving cochlear implants. Now a cochlear implant has an array with multiple electr... | g59708 | [
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<p>Take as an example the well-known <a href="http://deepblue.lib.umich.edu/handle/2027.42/22636">Boston housing dataset</a>. In the original paper, the regression model was used to model the amount people were willing to pay for improved air quality.</p>
<p>But the 'people' whose behaviour was being modelled was neve... | g59709 | [
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0.00713093439117074,
0.044704146683216095,
0.001992190023884177,
0.07620957493782043,
0.02316... |
<p>I have 4 clusters (see plot below) extracted from data of medical samples <code>N=218</code> measured for 11 genes/predictors <code>P=11</code> by this method: first PCA analysis validated to have 2 important PCs that explained 75% of the data, then different clustering algorithms, distances, linkages (in hierarchic... | g59710 | [
-0.015873635187745094,
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0.018968192860484123,
-0.001537923701107502,
0.031043222174048424,
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0.055082838982343674,
0.024377459660172462,
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-0.03548051044344902,
0.017665674909949303,
0.07527782768011093,
0.043921466916799545,
... |
<p>I have events that take a proportion of an observed time slice. The observed variable is the number of events happening at any one moment of time. Therefore the mean is merely the sum of proportions, the minimum is the count at a time where there are the least overlapping.</p>
<p><img src="http://i.stack.imgur.com/... | g59711 | [
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0.0024841385893523693,
0.06253752112388611,
... |
<p>To all,</p>
<p>I have performed a study where 50 patients underwent a computerized tomography (CT) scan. Each scan was reconstructed using 3 different algorithms (no noise reduction, medium noise reduction, high noise reduction). These reconstruction algorithms create noise reduction which is an issue when trying t... | g15409 | [
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0.046809494495391846,
0.020777780562639236,
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0.06347838044166565,... |
<p>I'm really confused here. I am trying to compare two sets of data which differ in sample size. One has 257 entries and the other has 598. They are measures of scores on two different assessment types where the only possible scores are 1 through 4, with half points allowed. The means are a half point different, the s... | g15410 | [
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0.00245994096621871,
0.035520363599061966,
0.013174569234251976... |
<p>I would like to compare the fit of two non-linear regression models:</p>
<p>1)
$$
Y = (\Pi^{10}_{i=1}\beta_i^{x_i})^{1/\Sigma \beta}
$$</p>
<p>2)
$$
Y = \begin{cases}
(\Pi^{10}_{i=1}\alpha_i \beta_i^{x_i})^{1/\Sigma \beta} & \text{for a predefined subset of datapoints} \\
(\Pi^{10}_{i=1}(1-\alpha_i)\beta_i^{x_... | g59712 | [
0.008958594873547554,
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0.028676653280854225,
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... |
<p>I want to attempt to use Support Vector Machines (SVMs) on my dataset. Before I attempt the problem though, I was warned that SVMs dont perform well on extremely unbalanced data. In my case, I can have as much as 95-98% -1's and 2-5% 1's. </p>
<p>I tried to find resources which talked about using SVMs on sparse/unb... | g15414 | [
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<p>In my Bayesian statistics class, my professor makes the remark that we should not be obsessed with unbiased estimator.</p>
<p>First: I understand this statement in the sense of trading biasedness for smaller variance, i.e. "good" estimator = estimator with smallest Mean Squared Error (MSE). This idea is seen in Fre... | g15220 | [
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<p>I am trying to predict whether or not captains in a particular groundfish fishery choose to fish on any given day and what variables may influence that decision. Originally I had planned on using vanilla logistic regression, where each captain decided to fish or not fish on any given day of the season in a particula... | g59713 | [
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<p>I have some univariate data which might be well modeled as a two component mixture where the first component is normal with unknown mean and variance and the second is some unspecified continuous distribution. The mean of the second distribution is greater than the mean of the normal.</p>
<p>The goal is to classif... | g15420 | [
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<p>I am generating a sequence of normal random variables (using the routines from boost C++ library). How fast would you expect the mean and the variance of the sequence converge to the actual variance? </p>
<p>In my case the true values are:</p>
<pre><code>mean=-0.01208333333333333
variance=0.0075
</code></pre>
<p>... | g15421 | [
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<p>In IV, I've sometimes seen the estimates compared to OLS to give a sense of how the LATE may compare to ATE. </p>
<p>What would the analogue be in fuzzy RD? What is the benchmark estimate? </p>
<p>I'd imagine the analogue would be the structural equation without instrumenting for the endogenous variable? Would... | g37642 | [
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<p>I am wondering about the distribution of the error term/innovation process in a ARCH/GARCH process and its implementation, I am not sure about some points. The basic assumption is</p>
<p>$r_t=\sigma_t*\epsilon_t$</p>
<p>where the $\sigma_t$ is the volatility, modeled by ARCH/GARCH and the $\epsilon_t$ are mostly a... | g59714 | [
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<p>Let $X$ and $Y$ be independent random variables with pdf
\begin{align}
f(x)&=p(1-p)^x,x=0,1,2,\ldots \\
f(y)&=(1+y)p^2(1-p)^y, y=0,1,2,\ldots
\end{align}</p>
<p>Find the MVUE for
$$
p(1-p).
$$</p>
<p>I know $X \sim $ Geometric$(p)$ and $Y \sim$ NegativeBinomial$(2,p)$.<br>
So the complete sufficient statis... | g15423 | [
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0.02090589702129364,
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<p>We have data from two sort tasks where the same items (N=87) were assigned to different types of group ('g' & 'd'). We want to compare the overlap between the assignments to the 'g' groups (N=13) to those of the 'd' groups (N=16). To give you an idea of the data I have created a truncated frequency table <em>(ap... | g15424 | [
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0.... |
<p>I am analyzing the number of donors cancelling commitments as a monthly time series which varies significantly with economic indicators, some according to internal data, and maybe according to season. I want to see the variance after adjusting for the economy and season (assuming the remainder of variance is due to ... | g44773 | [
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0.018400918692350388,
0.014017387293279171,
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<p>I am new, so please bear with me, until its correctly formulated:<br>
<strong>In short:</strong><br>
I am doing simultaneous non-linear regression (parameter estimation) of two different parametric models to three different, but related sets of measurements in an experiment. Some of the parameters in my parameter ve... | g59715 | [
0.03783967345952988,
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0.023739155381917953,
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0.038031160831451416,
0.02... |
<p>I have to compute and compare the least squares method on a model to the least trimmed method. </p>
<p>The LS model results were:</p>
<pre><code>Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -39.9197 11.8960 -3.356 0.00375 **
Air.Flow 0.7156 0.1349 5.3... | g15426 | [
0.01786871999502182,
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0.006435432471334934,
0.024310724809765816,
0.08397078514099121,
0.03... |
<p>I don't know the exact term for this, so googling didn't work. I will explain exactly what I need below.</p>
<p>I want to compare two sets of values such as blood sugar or blood pressure, where the values never start at 0. Please consider the example below:</p>
<p><strong>Update</strong></p>
<p>I compared the dur... | g44781 | [
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0.017084648832678795,
0.014751089736819267,
0.017162924632430077,
... |
<p>I know I'm missing something in my understanding of logistic regression, and would really appreciate any help.</p>
<p>As far as I understand it, the logistic regression assumes that the probability of a '1' outcome given the inputs, is a linear combination of the inputs, passed through an inverse-logistic function.... | g49831 | [
0.04625621810555458,
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0.043431635946035385,
0.026573024690151215,
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<p>I am working through the proof for partitioning sum of squares.<br>
Could someone please explicitly explain how one goes from line 14 to 15 in the following PDF:</p>
<p><a href="http://capone.mtsu.edu/dwalsh/4380/438PARTN.pdf" rel="nofollow">http://capone.mtsu.edu/dwalsh/4380/438PARTN.pdf</a> </p>
<p>That is, how ... | g59716 | [
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0.002472115680575371,
0.07780133932828903,
-0... |
<p>If I have a random variable that follows a normal distribution i.e.<br><br>
$X \sim N(-3,4)$ <br><br>
and I want to calculate $P(|X| <1)$ how would I go about doing so, using the z values? Seeing as it's the modulus, would I only need to consider one half of the normal curve and thus calculate $P(X<1)$?</p> | g59717 | [
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<p>I am faced with trying to demonstrate through testing an extremely low error rate for a sensor (no more than 1 error in 1,000,000 attempts). We have limited time to conduct the experiment so we anticipate not being able to obtain more than about 4,000 attempts. I see no problem showing the sensor does not meet the ... | g59718 | [
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0.0405750498175621,
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0.... |
<p>Im trying to understand how people use R packages and was wondering if there are documented cases where R packages have produced different answers.</p>
<p>Clarification: The motivation behind this question comes from an effort I'm involved in where the goal to understand the importance of provenance in the analytic... | g59719 | [
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0.011406904086470604,
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0.018317893147468567,
0.05... |
<p>I am a physician and clearly not a statistician (I try to understand why and how to perform the right analysis, but I don't understand the formulas). I am using SPSS v.19 in analyzing my data.
I try to analyze if a biomarker is associated with an increased mortality risk in a subpopulation from my study and I don't... | g59720 | [
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0.07722688466310501,
0... |
<p>I wish to compare proportions between two small groups.</p>
<p>In group 1, 2 of 18 students received honours. In group 2, 9 of 21 received honours. </p>
<p>This is a small sample, so if I use the t-test:</p>
<pre><code>x1 <- c(rep(1,2),rep(0,16))
x2 <- c(rep(1,9),rep(0,12))
t.test(x1,x2, alternative="two.... | g59721 | [
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0.03662863001227379,
0.0013733255909755826,
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... |
<p><a href="http://cran.r-project.org/web/packages/quadprog/quadprog.pdf" rel="nofollow">http://cran.r-project.org/web/packages/quadprog/quadprog.pdf</a></p>
<p>R package <code>quadprog</code> seems to be able to solve the quadratic programming problem only when the matrix $D$ is positive definite.</p>
<p>However, th... | g59722 | [
0.05242370441555977,
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0.0035993631463497877,
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0.004385277628898621,
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0.006677594501525164,
0.018475275486707687,
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0.018367061391472816,
0... |
<p>The recommendation problem is this:
Suppose that we have a matrix whose columns are items (e.g., movies) and whose rows are users. A small part of the matrix is filled with rating values. That is values (e.g. between 1 and 5) which represent how much a particular user likes a particular item. The problem is to predi... | g59723 | [
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0.020602034404873848,
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0.049080707132816315,
-0.018... |
<p>I have data on GDP growth as a dependent variable and growth in main production sectors of Pakistan such as mining, electricity, communication, manufacturing and electricity. I am supposed to run a regression on it. Is there any difference between multiple regression and multivariate regression? If so, than what is ... | g59724 | [
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<p>Let's say I'm trying to tell whether my company's sales have had a downward trend over the last 10 years. Let's also say I have available to me the last 10 years of quarterly sales. If I run a bivariate regression with time as the independent variable and sales as the dependent variable, and if the regression coef... | g59725 | [
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<p>Consider the dual with no offset and not slack. </p>
<p>In the dual we have that for data points that are support vectors:</p>
<p>$$\alpha_t > 0$$</p>
<p>and that the constraint is satisfied with equality (since a support vector!):</p>
<p>$$y^{(t)}\sum^n_{t'=1} \alpha_{t'}y^{(t')}x^{(t')} \cdot x^{(t)} = 1$$<... | g477 | [
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0.... |
<p>I'm working on some homework and cannot figure out this question so I thought I'd come here for some help.</p>
<blockquote>
<p>Part 1: A recent study of food portion sizes reported that over a 17-year period, the average size of a soft drink consumed by Americans aged 2 years and older increased from 13.1 ounces ... | g15445 | [
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0.0... |
<p>Suppose we have a sample $\boldsymbol{x}_i$ for $i$ in $1,\dots, n$, from a $d$-dimensional unimodal density $f(\boldsymbol{x})$. I would like to estimate the mode of $f(\boldsymbol{x})$. </p>
<p>The mean-shift algorithm discussed in <a href="http://stats.stackexchange.com/questions/33625/computationally-efficient-... | g59726 | [
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... |
<p>I have seen two different ways to formulate the SVM optimization but I was not sure what the difference was between them or if there was any difference.</p>
<p>First formulation:</p>
<p>$$min \frac{1}{2}||\theta||^2 + C \sum^n_{i=1}\xi_i $$
$$\text{s.t. }\ \ y^{(i)}(\theta \cdot x^{(i)} +\theta_0) \geq 1 - \xi_i$... | g15448 | [
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0.05... |
<p>I have two variables in a regression problem, where I predict the end interest rate for a loan application.</p>
<ul>
<li>x1: risk band (A+,A,B,C)</li>
<li>x2: initial rate (6%, 7%, 8%, 9%)</li>
</ul>
<p>Based on these two variables, I'm trying to predict what the actual end rate, y, will be (i.e 6.3%).</p>
<p>Ris... | g15450 | [
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0.0... |
<p>I'm new to Weka (and machine learning) so this question would be a bit silly.</p>
<p>So I have 2 models built using J48 and RandomForest (both run with 10-fold cross-validation mode) on a 40,000-tuple training set. I also have 6 different smaller test sets, each has around 8000 tuples.</p>
<p>Now I want to compare... | g59727 | [
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-0.004651971161365509,
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0.03122011199593544,
0.06749937683343887,
... |
<p>I have five millions of objects each of them having one or more tags. How do I compute statistically sound similarity score between each pair of the objects taking into account that:</p>
<ol>
<li>There are 100 millions of tags most of them used only once. </li>
<li>Some tags are used very often, say one tag may be ... | g59728 | [
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0.03742121532559395,
0.012169644236564636,
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0.008456775918602943,
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0.10032260417938232,
0.0124... |
<p>Long ago I learnt that normal distribution was necessary to use a two sample T-test. Today a colleague told me that she learnt that for N>50 normal distribution was not necessary. Is that true?</p>
<p>If true is that because of the central limit theorem?</p> | g49749 | [
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-0.012681564316153526,
-0.03192127123475075,
... |
<p>How comprehensive is the following book - What interpretations are missing?</p>
<p>Interpretations of Probability, Andrei Khrennikov, 2009, de Gruyter, ISBN 978-3-11-020748-4 </p>
<p><a href="http://www.degruyter.com/cont/fb/ma/detailEn.cfm?isbn=9783110207484&sel=pi" rel="nofollow">http://www.degruyter.com/con... | g59729 | [
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0.05544515699148178,
-0.07468116283416748,
0.09663097560405731,
-0.00... |
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