question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>As we all know, if you flip a coin that has an equal chance of landing heads as it does tails, then if you flip the coin many times, half the time you will get heads and half the time you will get tails.</p>
<p>When discussing this with a friend, they said that if you were to flip the coin 1000 times, and lets say ... | 69,616 |
<p>I was given this sample problem:</p>
<blockquote>
<p>Find the t-value such that the area under the t distribution to the
right of the t-value is 0.2 assuming 10 degrees of freedom.</p>
</blockquote>
<p>So, I went poking around in Excel and found a function called <strong>TDIST</strong>. I plugged in my values... | 69,617 |
<p>I am not an expert in statistics, but I would like to work on a SARIMAX model representing power consumption. The exogeneous variable would be the temperature, but for now I found <a href="http://www.jocet.org/papers/149-L013.pdf" rel="nofollow">here</a> I might need to do some cross-correlation study to go further.... | 30,093 |
<p>I want to estimate the transition matrix of first order markov chain.
I found that the transition matrix can be estimated by the sample proportion of state transition.
However, here is my question.
Is there any statistical relationship between sample size and number of state?
I found that the estimated transition ma... | 69,618 |
<p>I want to test a sample correlation $r$ for significance ($n=16$), using p-values, in Python. As I have understood from <a href="http://stats.stackexchange.com/questions/62824/when-is-fishers-z-transform-appropriate">this question</a>, I can achieve that by using Fisher's z-transform. </p>
<p>Is there a Python modu... | 69,619 |
<p>I have data from a psychology experiment in which participants were assigned to one of 3 training conditions and then gave responses for 16 trials for each combination of two within-subjects factors, section and format. Each response is classified as correct or incorrect. I originally calculated a % correct for ea... | 69,620 |
<p>Once or twice a year, we go through an elaborate and expensive process to measure leakage in a pipe. We calculate leakage via mass balance, so that:</p>
<p>\begin{equation}
Leak = X + Y - Z
\end{equation}</p>
<p>Depending on how well data was collected for each variable, we select particular assumptions. For... | 69,621 |
<p>The PyData ecosystem is growing quickly but it still has some important gaps in relation to what one can find in R. I believe some examples are survival analysis and to some extent grammars of graphics (although this gap is being filled quickly with <a href="https://github.com/wrobstory/vincent" rel="nofollow">Vince... | 30,172 |
<p>I have an issue with a result I just found.</p>
<p>I ran a sub-population analysis (for 2 age groups) with a complex survey design. </p>
<p>For this purpose I fitted a generalized linear model (family:normal,link:identity), using the function <code>svyglm</code> from the R package <code>survey</code>. </p>
<p>Her... | 30,173 |
<p>I have a set of five variables that are highly correlated (namely SAPS3, SIDA, ALBUM, Lactate), and I must see how they are associated with other variables (I will use a variable named lIL6 as an example). </p>
<p>I have decided to use principal component analysis to deal with collinearity and try to understand how... | 30,175 |
<p>I'm struggling slightly with part of a homework problem. We are asked to</p>
<p>"describe the distribution of weights, at the school level"</p>
<p>There are n=220 students in total</p>
<p>There are p=38 schools</p>
<p>I have produced a matrix of histograms; one for each school. With so few students per school I ... | 46,753 |
<p>Let$ X_1, ...,X_n$ be a random sample feom a distribution $Geometric(\theta)$ for $0<\theta<1$. I.e,</p>
<p>$$p_{\theta}(x)=\theta(1-\theta)^{x-1} I_{\{1,2,...\}}(x)$$</p>
<p>Find the unbiased estimator with minimum variance for $g(\theta)=\frac{1}{\theta}$</p>
<p><strong>Myattempt:</strong></p>
<p>Since t... | 69,622 |
<p>This is a homework problem. Suppose we have a random sample $X_1,\ldots,X_n \overset{iid}{\sim} F$ with density $f(x) = 2(x-\theta)$ for $x\in (\theta,\theta+1)$. Let $X_{(1)} = \min{\{X_1,\ldots,X_n\}}$. Show $X_{(1)} \overset{P}{\longrightarrow} \theta$. </p>
<p>My attempt:</p>
<p>A few calculations first:</p>
... | 30,178 |
<p>I want to solve an imbalanced data classification, with small number of data points (approximately 600 ) with the ratio of true labels to false , 1:12. Is there any function or matlab code for using Random forest for classification of imbalanced data? How should I access it and set the parameters?
Thank you for yo... | 69,623 |
<p>Suppose that we have have scoring functions $f(\textbf{x})$ and $g(\textbf{x})$ for classifying an object as red or blue. These are based on linear discriminant analysis. So if $f(\textbf{x}) > g(\textbf{x})$, then the object is red. Why is the posterior probability that an object is red the following:</p>
<p>$$... | 69,624 |
<p>I have two multivariate gaussian distributions $ x, y $ and am trying to find just $ p(x|y) $.</p>
<p>Every website I find gives these formulas $ \mu = \begin{pmatrix} \mu_x \\ \mu_y \end{pmatrix} $ and $ \Sigma = \begin{pmatrix} \Sigma_{xx} & \Sigma_{xy} \\ \Sigma_{yx} & \Sigma_{yy} \end{pmatrix} $</p>
<p... | 69,625 |
<p>I've tried to understand what is done with score plots and loading plots.</p>
<p>I've searched the web but I seem to not get it anyways.</p>
<p>Could anyone tell an actual example or similar using score plots? Where does these score come from? From what I've understood it is the value of the principal component wh... | 30,181 |
<p>I am working on a binary data classification problem. The dataset is imbalanced, it consists of 92% 'false' labels and 8% 'true' labels. The number of features is 18 and I have a small number of 650 data points. I want to use boosting algorithms in MATLAB like <code>GentleBoost</code> to solve this problem. I assign... | 69,626 |
<p>This is a homework problem. If $X_n$ converges in probability to 1, show $X_n^{-1}$ converges in probability to 1. </p>
<p>My attempt:</p>
<p>$$\begin{align*} P(|X_n^{-1}-1| > \epsilon) &= P(|X_n^{-1}-X_n + X_n-1| > \epsilon)\\
&\leq P(|X_n^{-1} - X_n| > \epsilon/2) + P(|X_n - 1| > \epsilon/2)... | 69,627 |
<p>This is a softmax probability distribution:<br>
$$P(i| w_1, w_2, \ldots, w_n) = \frac{exp(w_i)}{\sum_{i=1}^n exp(w_i)}.$$</p>
<p>It known also as Boltzmann distribution. It is used in generalized Bradley-Terry model and in multinomial logistic regression. There are efficient minorization-maximization algorithms for... | 69,628 |
<p>Suppose I have a biased coin (heads with probability p), and I keep flipping it until I get t tails. So I had to flip n times in total to get t tails. How do I find a (frequentist) confidence interval for the probability of heads p?</p> | 177 |
<p>I start with three independent random variables, $X_1, X_2, X_3$. They are each normally distributed with: </p>
<p>$$X_i \sim N(\mu_i, \sigma^2), i = 1, 2, 3.$$</p>
<p>I then have three transformations, </p>
<p>$$\eqalign{
Y_1 &= -X_1/\sqrt{2} + X_2/\sqrt{2} \cr
Y_2 &= -X_1/\sqrt{3} - X_2/\sqrt{3} + X... | 30,186 |
<p>I'm currently applying the Roy Zelner test of poolability as shown
in the excellent <a href="http://doc.rero.ch/lm.php?url=1000,42,6,20080417092244-DQ/wp0804.pdf" rel="nofollow">article of Andrea Vaona</a>,
in fact I'm working with panel N=17 T=5, and my model looks like
this :
$$Y_{it}= a_0+B_1X_1+B_2X_2+B_3X_3... | 37,829 |
<p>I have a real-life situation that can be solved using Queueing Theory.<br>
This should be easy for someone in the field. Any pointers would be appreciated.</p>
<p><strong>Scenario:</strong><br>
There is a single Queue and <strong>N</strong> Servers.<br>
When a server becomes free, the Task at the front of the queu... | 69,629 |
<p>I'm working on a model that requires me to look for predictors for a rare event (less than 0.5% of the total of my observations). My total sample is a significant part of the total population (50,000 cases). My final objective is to obtain comparable probability values for all the non-events, without the bias of the... | 69,630 |
<p>I have a set of abnormal lab findings and a set of tenderness outcomes in a small sample of "cases" and "positive controls". We hypothesize there may be some lab findings which differentially affect cases and controls. For instance, abdominal tenderness may be associated with pain in the controls but not in cases, o... | 28,299 |
<p>Is it okay to use Adaboost to do feature selection (selecting a subset of dimensions $S$ from a high-dimensional feature vector $V$)?
I divided the samples into four non-overlapping sets: $A$ (training1), $B$ (validation), $C$ (training2), $D$ (testing).
There could be two procedures to do Adaboost feature selection... | 69,631 |
<p>Suppose we have a multiple comparisons scenario like such as <em>post hoc</em> inference on pairwise statistics, or a multiple regression, where we are making a total of $m$ comparisons. Suppose also, that we would like to support inference in these multiples using confidence intervals.</p>
<p><strong>1. Do we appl... | 69,632 |
<p>I have a logistic regression with data that are kind of like this:</p>
<pre><code>y <- rep(c("A", "A", "B"), each = 30)
x <- c( rep(1, 12), rep(2, 18), rep(3, 16), rep(4, 12), rep(5, 2),
rep(1, 3), rep(2, 5), rep(3, 8), rep(4, 10), rep(5, 4) )
da <- data.frame(y = y, x = x)
table(da)
x... | 26,173 |
<p>The UNDP have <a href="http://www.un.org/millenniumgoals/pdf/report-2013/mdg-report-2013-english.pdf" rel="nofollow">report</a>ed that the millennium goal of halving the percentage of people living below 1 USD (PPP) a day has been met (compared to 1990). I was looking at <a href="http://mdgs.un.org/unsd/mdg/Data.asp... | 69,633 |
<p>My intention is to use SVR with 1-10 independent variables to best predict a dependent variable. After separating the data into scaled training and testing files containing the independent variables and dependent variable and running svm-train and svm-predict, I find that the output_file of svm-predict has a strong ... | 17,973 |
<p>Hopefully this is an easy question:</p>
<p>When doing a regression in log log form (ie log(y) = log(x)) is it ok to use independent variables (xs) that are already in % terms. </p>
<p>Random example: Log(inflation rate) = Log(Capacity Utilization) </p>
<p>Where both or either of the variables are in percents. ... | 30,193 |
<p>Using a simple ordinary least squares regression:</p>
<p>$
Y = \alpha + \beta \times X$</p>
<p>we can estimate the dependent variable $Y$ through the regression parameters of $\alpha \text{ and } \beta$.</p>
<p>In what way is the estimated $Y$ "better" than the original $Y$?</p> | 30,194 |
<p>Given a continuous probability density function $f(x)$, whose Taylor expansion is $f(x) = \sum\limits_{n=0}^\infty a_n x^n$ with radius of convergence $r$. <strong>Can we say something about the relationship between $r$ and the tail behavior of $f$?</strong> For example, for the normal density, $r=\infty$ and the it... | 69,634 |
<p>Suppose my pdf is some function that requires that $x\geq0$ or else it becomes $0$. Also, the parameter is $\theta>0$. Now, I would like to calculate the MLE of that pdf for $X_1,...,X_n$ i.i.d. random variables. </p>
<p>Now, suppose I differentiated with regards to the log-likelihood and found that the derivati... | 69,635 |
<p>I would like to run a lagged random effects regression.</p>
<p>The data is from an experiment in which participants were assigned to groups of five and participated in an interactive game for 20 rounds.</p>
<p>Participants could exchange something during the experiment, which is the dependent variable.</p>
<p>Now... | 69,636 |
<p>Can I write $\text{Cov}[x,y+z]=\text{Cov}[x,y]+\text{Cov}[x,z]$,</p>
<p>where $\text{Cov}(.)$ is referring to the population covariance? $x,y$ and $z$ are random variables.</p>
<p>(very fundamental question... :)</p> | 69,637 |
<p>X=Normal(0,1) random var.
Y=Uniform{-1,1} random var.
Show that Z=X.Y is normal random variable.</p>
<p>Thanks for your help in advance.</p>
<p>I tried to solve it through double integral but it failed to do. There should be a trick to solve this.</p> | 69,638 |
<p>Let $X_1, ..., X_n$ be iid with a distribution F.</p>
<p>Let $\theta$ be the median of F.</p>
<p>What is the value of $E(X_i \cdot I(X_j>\theta))$?</p>
<p>If $i\neq j$, then $E(X_i \cdot I(X_j>\theta))= 1/2 \cdot \mu$, right?</p>
<p>When $i=j$, I don't seem to find it...I'm looking for an expression in fun... | 69,639 |
<p>I was asked to calculate average variance extracted (AVE) to establish discriminant validity; I've ran CFA but ask how to calculate AVE following Fornell & Larcker’s (1981) test when having two latent variables.</p> | 69,640 |
<p>I am new here - and relatively new to statistics, data mining and R. I am trying to understand why my data is not clustering correctly - or if I am reading it wrong. Shortly about the project:</p>
<p>My data points are behavior of online gaming users over time (one observation for each user). I am trying to cluster... | 30,205 |
<p>I've run a MLM using lmer in R on some data that I have. As I'm analysing binary data, I've used a binomial MLM as well. I basically have a simple question about how to report the coefficients from the model.</p>
<p>I've read that the best thing to do with the binomial coefficients is to back-transform them using t... | 69,641 |
<p>I'm confused as to the correct formula for approximate degrees of freedom to use for Welch's t-test. Satterthwaite's (1946) formula is the most commonly cited formula, but Welch gave an alternative in 1947. I'm not sure which is preferable (or used by most statistical software).</p>
<p>Satterthwaite's formula:
$$\f... | 69,642 |
<p>for example- measure of participant’s task performance (0%-100% scale), the participant self judgment of his own performance (1-7 scale) and an observer's judgment of the participant’s performance (1-7 scale)?
thank you,
Tomer</p> | 69,643 |
<p>I am really stunned by the fact that the Poisson GLM accepts non-integer numbers! Look:</p>
<p>Data (contents of data.txt):</p>
<pre><code>1 2001 0.25 1
1 2002 0.5 1
1 2003 1 1
2 2001 0.25 1
2 2002 0.5 1
2 2003 1 1
</code></pre>
<p>R script:</p>
<pre><code>t &l... | 769 |
<p>I will try to be as specific as possible and I do hope that someone can steer me on the right track.</p>
<p>I have 1 categorical variable for grade consisting of grade 1, 2, 3 and 4 which will be dummy coded. I also have 4 continuous predictor variables. Now, the perplexing part is I would like to know if it is pos... | 30,208 |
<p>In the proof of the delta method related with the convergence in distribution, I couldn't understand the statement below.</p>
<p>When $ \sqrt{n} (X_n - \mu) \rightarrow ^D N(0, \sigma^2 ) $ ,</p>
<p>\begin{equation}
f(X_n) = f(\mu) + f'(\mu)(X_n -\mu ) + o_p (|X_n - \mu |),
\end{equation}</p>
<p>where $a_n = o_p(... | 30,209 |
<p>I've recently come across this formula from an ITU-T standard in a project that I'm working on.</p>
<p>The application of the formula is to compare two vectors containing some per frame statistics from two very similar video signals, and try to find any evidence of a delay of $n$ frames between them, i.e. that the ... | 69,644 |
<p>I'm new to this, and am struggling with the concept of how to determine what is the independent variable and what is the dependent variable. </p>
<p>Here's an example that I think would go a long way for me:
I'm studying baseball, specifically the home run rate for all players over the course of the season. Is the ... | 69,645 |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://stats.stackexchange.com/questions/35123/whats-the-difference-between-variance-and-standard-deviation">What's the difference between variance and standard deviation?</a> </p>
</blockquote>
<p>I know the standard formulas for these but t... | 49,832 |
<p>Does anyone know of a good resource listing known tricks (with examples?) for calculating closed form expressions from messy expectations? (e.g., moment generating function, law of iterated expectations, change of measure, etc.) </p>
<p>In a different setting, I've found <a href="http://www.duke.edu/~rnau/arimrule.... | 42,339 |
<p>I have a database of workers, customers, and jobs, and I want to analyze my data to see if a given worker is performing well above or below the mean. I've come up with something of a solution, and I'm interested in hearing if there are any flaws in my current approach. </p>
<p>My goal is to see if a given worker ha... | 30,216 |
<p>I have been working with simulations, among them scheduling simulations. Each simulation chooses the number of steps, the arrival rate of new jobs and the duration of each step for each job. Thus, each simulation is an instance of a problem.</p>
<p>I would like to compare various algorithms for scheduling these ins... | 30,217 |
<p>I have the following model and want to make a table with the interpretation of the interaction effects as suggested by Bambor and Clark in <a href="http://pan.oxfordjournals.org/content/14/1/63.full.pdf+html" rel="nofollow">this paper</a>. However, I have no idea on how to calculate the $cov(\hat{\beta_1}, \hat{\bet... | 69,646 |
<p>An example like the t-distribution with 2 degrees of freedom would not suffice as the second moment exists but equals inf.</p> | 69,647 |
<p>I would like to prove the following statement:</p>
<blockquote>
<p>If the $r$th moment of a random variable $X$ exists and is finite,
then all moments $1$ to $r-1$ exist and are finite.</p>
</blockquote>
<p><strong>Edit</strong>: I mean the raw moments $\mathbb E X^r$. By <em>exists</em> I mean <em>exists and ... | 69,648 |
<p>I have made 9 models using simple linear regression. I'm now checking that each of models meets the assumption of homogeneity of variance. Each of the models used either categorical or numeric (year as an integer) IVs. I carried out a Levenes test either at each level of a categorical IV or against the integer IV (y... | 40,497 |
<p>When I convert some data for a model (e.g., wealth, pollution) into per capita figures (e.g., wealth per inhabitant, tons of pollution per inhabitant) is this a transformation or re-expression of the data? Or is the term transformation or re-expression reserved for logarithmic or exponential transformations (includi... | 69,649 |
<p>I have a quite flat likelihood leading Metropolis-Hastings sampler to move through the parameter space very irregularly, i.e. no convergence can be achieved no matter what the parameters of proposal distribution (in my case it is gaussian). There is no high complexity in my model - just 2 parameters, but it seems th... | 69,650 |
<p>I have a data set with a range of 0 to 65,000. The vast majority of data points (it is a huge sample) are concentrated between 0 and 1000. There is only one point that has 65,000. I want to plot this using a semi-logarithmic plot. However, I would like the graph to have around 50 points. If I use scales like 2,... | 69,651 |
<p>Can anyone show how the expected value and variance of the zero inflated Poisson, with probability mass function</p>
<p>$$
f(y) =
\begin{cases}
\pi+(1-\pi)e^{-\lambda}, & \text{if }y=0 \\
(1-\pi)\frac{\lambda^{y}e^{-\lambda}}{y!}, & \text{if }y=1,2....
\end{cases}
$$</p>
<p>where $\pi$ is the probabi... | 30,222 |
<p>I'm new to clustering. recently I've implemented agglomeration clustering, I understood that we merge clusters that have distance < Threshold. </p>
<ol>
<li>But how to fix the Threshold?</li>
<li>How to choose right method for finding distance [euclidean, manhattan,..]?</li>
<li>How to evaluate my clusters?</li... | 69,652 |
<p>I am looking for the most efficient way to fit a noncentral chi-squared distribution with fixed d.o.f. to a given data set. So the inputs are d.o.f. and the data and the output should be the noncentrality parameter that gives the best (maximum likelihood? or any other approach that would be more computationally effi... | 30,224 |
<p>I'm looking at a variable that has two options: "Presence of Condition" has two headings "Yes" and "No" with large numbers of both. I'm trying to figure out how to consolidate both so that I can have one variable "Presence of Condition" and use that data to correlate with other variable. I'd have to separate the cor... | 69,653 |
<p>I'm actually working on an information retrieval project, and I want to extract words that are of significance from a sentence. This is somewhat opposite to stopwords.</p>
<p>In a sentence like: He was a great astrologer and an orthodontist.</p>
<p>... I want to extract out words that might be of more importance. ... | 30,226 |
<p>Can I show that
$$
P(Z\ge Z_{1-a} - C) > (P(Z\ge Z_{1-\sqrt\alpha}-C/\sqrt2))^2
$$
for every positive number $C$?</p>
<p>($Z_a$ is the quantile $a$ of the standard normal distribution.)</p>
<p><strong>What I Tried:</strong>
In a simulation I couldn't disprove it. I wrote the function:
$$
f(C)=1-\Phi (Z_{1-a} - ... | 69,654 |
<p>I have tested male and female participants in one visual search task. </p>
<p>The task included 3 different types of displays (1 factor, 3 levels); meaning I have 3 means for each male or female participant. So the design is 2 (gender: f/m) x 3 (RT: M1/M2/M3). Is this analysis called a repeated measure ANOVA? </p> | 44,657 |
<p>I am trying to simulate a process as an absorbing Markov chain model, but I haven't been able to find the scenario that I am interested in looking at in the typical discussions of Markov chains online. Hoping someone out there will have some pointers.</p>
<p>In the chain I am building, there are certain transition... | 40,507 |
<p>Breiman et al recommend the 1-SE rule, and show that it is successful in screening out noise variables. At page no. 80 of their <a href="http://rads.stackoverflow.com/amzn/click/0412048418" rel="nofollow">book</a>, I get confuse about the '1 S.E. Rule'.
$$R'[T(k_l)]\leq R'[T(k_0)]+S.E\{R'[T(k_0)]\} $$ ... | 30,233 |
<p>I have two samples as follows:</p>
<pre><code>conjps <- c(9.41,10.45,10.78,10.73,11.11,11.12,11.59,11.04,11.63)
ms <- c(4.11,5.10,5.70,6.46,6.04,6.16, 6.24,6.32,7.33)
</code></pre>
<p>I want to test if the change of sample is the same to the another one.</p>
<pre><code>conjps_ch <- c(1.04,0.33,...)
ms &l... | 69,655 |
<p>Using a very simple set of data I ran a simple correlation using Google spreadsheet. I got a -.83+ correlation, which is pretty strong. So now I am wondering what else I might be able to determine. The total is unit sales for a year and the unemployment rate is reported for the similar MSA so I'm wondering whether I... | 69,656 |
<p>I have modeled claim frequency data using Poisson regression and claim amount using gamma. I have seen the <a href="http://en.wikipedia.org/wiki/Tweedie_distributions" rel="nofollow">Tweedie compound Poisson gamma distribution</a> used to model aggregate claim data. I am quite new to R and I am trying best to model ... | 69,657 |
<p>I have at least two time series. How can I measure which one of them is more random than the others?</p>
<p>I am also interested in monitoring the changes in the amount of randomness over time for an individual time series. </p>
<p>Thanks</p> | 69,658 |
<p>I collected data on one sample, the DV could be separated into two groups (success yes vs. no) and then I have several IVs with interval scale. I just don't know if to use Wilcoxon or Man-Whitney test. Also I don't know if it's necessary to use Bonferroni correction or if that is just important for parametric tests.... | 69,659 |
<p>I am just beginning to discover the possibilities of machine learning and I have a naive question:
First, does Recursive classification tree method (as shown in party package in R, the ctree function) need a training group and then a test group ?
Second, I have few X parameters (6), 246 observations and an binary Y... | 30,236 |
<p>My name is Madelaine, I am doing research on the party list rankings for open list elections.
Using a range of explanatory variable (age, education, etc.) I try to estimate the rank a candidate has on a party list.</p>
<p>As my dependent variabele (rank) is ordinal, I wanted to used a ordered logistic panel data re... | 30,237 |
<p>I need the output of different classification algorithms over the same dataset.</p>
<p>Edit: I'm stating it more precisely. Suppose that a set of objects $S$ is given, and different algorithms $A_1,A_2,\ldots,A_n$ are applied to it: $A_i:S\rightarrow\mathcal{P}(S)$. The output of each of the algorithms is a set cov... | 36,212 |
<p>When comparing the same string sequences in the example below, why does the first call return 0 instead of 7? LCS.ex1[3,] is "S-U-M-S-SC-UC-MC" and LCS.ex2[1,] is also "S-U-M-S-SC-UC-MC". </p>
<p>Does one always have to pass in a sequence type with only one value for this function (and seqdist) to work? How can I r... | 30,239 |
<p>I'm trying to build a logistic regression model to predict 90+ Days past due(DPD) events. The size of the database is 96000, with an event rate of 6%. We ran the entire data set through the info value process, and converted it into Weight of Evidence (WOE) bins. When I try to build the model using 60% of the data (f... | 40,985 |
<p>I am trying to understand what can be proved about minimum variance estimators. I am a little confused by Cramér–Rao and how to apply it even to really simple examples or if it's even the right tool in this case.</p>
<p>Let us assume we have some finite set $S$ of elements, and we just want to estimate the cardinal... | 30,242 |
<p>I'm trying to run ANCOVA in SPSS, with a continuous IV as well as a continuous covariate.</p>
<p>Variable Information: </p>
<ul>
<li>1 DV: Continuous</li>
<li>2 IVs: 1 Continuous and 1 Categorical</li>
<li>1 Covariate: Continuous</li>
</ul>
<p>I am most interested on the interaction of the 2 IVs on the DV.</p>
<... | 40,997 |
<p>I am doing MANOVA. I have a within-subject factor "fatigue". One variable is fatigue (baseline, fatigue, rest). One of the dependent variable is the amplitude of swallowing muscle activity (T_tot_d when baseline, when subjects are fatigued, _tot_d after subjects rested). The only factor I have is Fatigue, which is t... | 11,874 |
<p>We want to explore the cross sectional association of 5 symptoms of psychopathology with functional impairment. </p>
<p>If we just take people who score high on symptom 1, then high on symptom 2, etc., and look at the means of social impairment in these groups, one particular symptom (let's call it symptom 1) stand... | 69,660 |
<p>Why do the absolute probabilities affect the p-value of a chi-square test so much? For example: </p>
<pre><code>> successes.1 = c(400, 500)
> successes.2 = c(40, 50)
> trials = c(1000, 1000)
> test.1 = prop.test(successes.1, trials)
> test.2 = prop.test(successes.2, trials)
> test.1
2-sample... | 11,875 |
<p>What's another word for "tails" when referring to the narrow ends of distributions? </p>
<p>Or is there another word for distribution tails? </p>
<p>It seems like I heard something else used before (e.g., x & y axes, abcissa & ordinate, or horizontal & vertical axes)</p> | 69,661 |
<p>I've been futzing around with the following example, and feel that there must be a good explanation or reference that I am blindly missing.</p>
<p>Supposer you have a linear relationship between two variables. Let's even assume that the intercept goes through 0. Why would there be more power in analysis by regres... | 30,245 |
<p>I have two datasets whose densities look clearly different. However, when I use the KLdiv function, it gives me a value of 0 and I don't understand why. Any suggestions on where I am going wrong? Datasets are at the end of this post.</p>
<p>I did something like this:</p>
<pre><code>library(flexmix)
KLdiv(cbind(den... | 69,662 |
<p>I have a question about measuring a confidence interval for a binomial success rate using from a "small" universe. I should say that I don't think that the underlying distribution is binomial for reasons I will explain below. </p>
<p>We rate success and failure of projects. Projects can either succeed or failure. E... | 69,663 |
<p>I have fitted the following linear mixed model based on the results of an economic game:</p>
<p><code>lmer(TotalScore~perOOgivenP+Game+(1|Subject),REML=T,data=mdl1table)->m1</code></p>
<p><code>TotalScore</code> is a integer.<br>
<code>perOOgivenP</code> is a proportion between 0 and 1 (most of which are 0).<br... | 69,664 |
<p>I have data from a load test of an automated system with several thousand data points that cover roughly 1 week of operation. I need to compare several algorithms for this system to see which is faster, if any (the metric used is the response time of the algorithm in milliseconds). Since it's technically impossible ... | 37,964 |
<p>I am running a 2x2 mixed method ANOVA (with one between-group factor and one within-group factor - time 1 and time 2). I want to check whether the assumption of normality of residuals is met. When I run the ANOVA in SPSS I get two sets of residuals if I save the unstandardised residuals - one for time 1 and one for ... | 30,247 |
<p>Let's say I have a simple 2x2 factorial experiment that I want to do ANOVA on. Like this, for example:</p>
<pre><code>d <- data.frame(a=factor(sample(c('a1','a2'), 100, rep=T)),
b=factor(sample(c('b1','b2'), 100, rep=T)));
d$y <- as.numeric(d$a)*rnorm(100, mean=.75, sd=1) +
as.numer... | 69,665 |
<p>I have a dataset of data and two of the fields are user comments - (I did not design this form) </p>
<p>I would like to know if there is anything I can do to get any information from a comments field - are there any best practices out there to make use of this type of data in a report / analysis ?</p>
<p>Otherwise... | 69,666 |
<p>My question is: </p>
<p>Is there a way to either force <code>Anova()</code> to somehow analyze <code>gls</code> objects (which internally are almost identical to <code>lme</code> objects), or force <code>Anova()</code> to honor the <code>test.statistics='F'</code> argument, or at least do a valid type-II sum of squ... | 69,667 |
<p>I've run into a simple problem - but no idea how to access it correctly.<br>
I've 85 people asked concerning their social network; first example: how many friends do you have. Second, what gender is each of this friend. Then I do a table which displays the average number of female friends and the average number of m... | 69,668 |
<p>I am working on finding the relationship between equity, gold, crude oil, and currency value. I used the Johanson cointegration test. Trace test indicates 4 cointegrating equations at the 0.05 level. For using VECM the rank for cointegration in Eviews has a maximum of 3. What is the problem in this model? How do yo... | 30,250 |
<p>I am wanting to fit a Poisson distribution but I am wanting to weight some of the values as more important. Is there a way to do this in R with <code>fitdistr()</code> or some equivalent function? Here is what I have at the moment:</p>
<pre><code>randoms <- rpois(15,10)
weighting <- seq(1, 100, by=1)
fit <... | 69,669 |
<p>Recently, there are several estimators have been proposed to estimate the average treatment effect (ATE) in observation studies, such as IPTW, doubly-robust estimator, etc. It fully makes senses to me for using these estimators to estimate ATE when outcome variable is continuous. However, it does not make any sense ... | 69,670 |
<p>Let me say thanks in advance. </p>
<p>I'm working with a set of data that contains reported coyote sightings. I use 2/3 of the data for model calibration along with an equal number of pseudo absences. I developed all possible models and ranked them according to their AIC weights. I chose the top models, who's weigh... | 69,671 |
<p>I have 100 geographical regions in a country. For each region the total number of houses and the number of vacant houses have been collected yearly over 20 years. I have also some other economic indicators at the country level (GDP, interest rate etc.). Now, given the forecasts for these indicators for next year, I ... | 69,672 |
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