question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>What do you think are the papers that each graduate student in machine learning and data mining should be aware of?</p> | 70,281 |
<p>I currently preparing a presentation for a university course in "Visual Data analysis". And one of my topics is the "Star Coordinate" visualization. <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.4.8909&rep=rep1&type=pdf" rel="nofollow">Star Coordinates</a></p>
<p>As Star Coordinates perf... | 31,134 |
<p>How do we explain the difference between logistic regression and neural network to an audience that have no background in statistics ? Thank you.</p> | 70,282 |
<p>Here is the summary of my sequence data generated in the SPELL format. All sequences are supposed to have the same length of 1440, but the summary tells me that they are not the same (see "min/max sequence length:91/1440").</p>
<p>I want to find the rows: </p>
<ol>
<li>that do not have the 1440 sequence length <... | 70,283 |
<p>I have a population of data points. Each data point expresses a different name. Each such name belongs to a different ethnicity, say {A, B, C, D, E}, with a probability. The sum of probabilities for a given name equals to 1. We also have some global weights; the probability a random picked name belong to each of the... | 31,136 |
<p>Consider an integer random walk starting at 0 with the following conditions: </p>
<ul>
<li><p>The first step is plus or minus 1, with equal probability. </p></li>
<li><p>Every future step is: 60% likely to be in the same direction as
the previous step, 40% likely to be in the opposite direction </p></li>
</ul>
<p... | 321 |
<p>I am doing a discriminant function analysis and I have four continous independent variables
and one categorical dependent variable (that has 3 groups). I have
chosen to do this analysis to see how these groups
can be predicted by the four independent variables. </p>
<ul>
<li><p>Firstly, when we are interpreting the... | 41,632 |
<p>The following is my experience doing some researches linked to statistical concepts. In the most situations I had no idea on <code>how to organize the questions</code>, <code>how to ask for answers</code>, and <code>how to provide feedback</code> showing my acceptance or rejection. I'm certainly not talking about th... | 41,633 |
<p>I have two samples of data each estimates of a position <code>x, y</code> with Gaussian noise. One source has a larger variance than the other. Is this source in any way useful in providing a better estimate of the true position than the source with lower variance or should it just be discounted?</p> | 49,455 |
<p>Tools such as random forests or adaboost are powerful at solving cross-sectional binary logistic problems or prediction problems where there are many weak learners. But can these tools be adapted to solve panel regression problems? </p>
<p>One could naively introduce a time index as an independent variable but all ... | 70,284 |
<p>I have collected 70 organisms from 4 different sites; two sites of treatment 1 and two sites of treatment 2. I also have a continuous explanatory variable (average temperature) which is different for each site. How can I test if measures of richness and diversity differ between sites or by temperature?</p>
<p><s... | 47,634 |
<p>Zhang and Yu (1998) proposed a formula to convert Odds Ratios (OR) to Risk Ratios (RR) for cohort studies:</p>
<p>$$RR = \frac{OR}{(1 - P_u) + (P_u\cdot OR) }$$
($P_u$ = incidence rate of the unexposed group)</p>
<p>Is there a similar strategy for a clogit model (matched case control study)? Or is it even pos... | 70,285 |
<p>I am struggling with two questionnaires. One comprises of 61 items explaining several components of emotional intelligence with 6 point scale while on the other hand 10 items making empathetic listening with 7 point scale. Can I correlate the factors obtained from these two questionnaires? If any scale modification ... | 40,629 |
<p>For my research I am currently working in R and I have created a function which gives me the loglikelihood. Now, I would like to optimize it for multiple parameters. So I decided to use the optim() function in R.</p>
<p>Since I have 1 vector parameter and another parameter which are constrained to have values betwe... | 31,147 |
<p>I am running a Monte Carlo Simulation and am sampling randomly from about 65 Normal Distributions, each with a different $\mu$ and $\sigma$. I end up with the Mixture Distribution graph shown below amd trying to evaluate the cause of the 2nd peak. The plot appears to be on the way to becoming bi-modal, with increase... | 31,148 |
<p>I recently interviewed farmers about their memories of annual crop production and compared this with diaries they had kept recording actual quantities harvested. I would like to know where interviewees’ recollections sit within the range of production values and how much confidence I can place in their recollections... | 14,815 |
<p>Are there R packages that offer eigenvalue de-noising methods grounded in Random Matrix Theory? Various cleansing methods include the Power Law and Krazanowski filter.</p> | 31,151 |
<p>When doing a GLM and you get the "not defined because of singularities" error in the anova output, how does one counteract this error from happening? </p>
<p>Some have suggested that it is due to collinearity between covariates or that one of the levels is not present in the dataset (see: <a href="http://r.789695.n... | 241 |
<p>Let's say I have a data matrix X where one feature is a factor with 8 levels. If I change this to be 7 indicator variables of 1's and 0's, do I need to make these columns factors as well? Or if I am training a model on this converted dataset should I just treat these new 1 and 0 values as continuous and scale accord... | 31,152 |
<p>I'm working with a GLM to try and optimize the model, and there are 152 predictive variables. A LOT of these are not significant, so I'm trying to figure out which ones to remove through use of the step() function. However, I'm having trouble interpreting the AIC output because it seems as if the models chosen have ... | 70,286 |
<p>Kevin Murphy's Kalman Filter toolbox (for Matlab) contains an example where it's the fact that the state space system in not identifiable causes problems. I include the example in it's entirety but you won't actually be able to run the code without installing the toolbox first. See the comments between the code bloc... | 70,287 |
<p>I am calculating the ICC as per the method of Shrout-Fleiss (1979), using the (3, 1) model in which the judges are fixed as are the targets. Some of my ICC values are negative. Is this to be expected? How to interpret this? I understand that the maximum ICC is 1.0, but is there a minimum value? How are negative... | 70,288 |
<p>I have calculated autocorrelation on time series data on the patterns of movement of a fish based on its positions: <em>X</em> (<code>x.ts</code>) and <em>Y</em> (<code>y.ts</code>).</p>
<p>By using R, I ran the following functions and produced the following plots:</p>
<pre><code>acf(x.ts,100)
</code></pre>
<blo... | 70,289 |
<p>I have run two separate logistic regressions and would like to assess which model fits the data better. Each model has 1 predictor.</p>
<p>Here's the output for both:</p>
<p>Model 1:</p>
<pre><code>Deviance Residuals:
Min 1Q Median 3Q Max
-1.280 -1.046 -1.046 1.078 1.315
Coefficients:
... | 907 |
<p>I have been doing some reading about <a href="http://en.wikipedia.org/wiki/Adaptive_simulated_annealing" rel="nofollow">adaptive simulated annealing</a> and as far as I know it is an algorithm that is really useful when it comes to finding the global maxima/minima of some functions, which is useful for calibration p... | 70,290 |
<p>I'm working on movie recommendation algorithm. The data set consists of about 40 million ratings (user, film, rating). I want to separate the ratings into two groups - training set and probe set. The training set will be used for training, probe set for checking that the algorithm doesn't overfit the data.</p>
<p>M... | 49,800 |
<p>I recently implemented a Kalman filter on the simple example of measuring a particles position with a random velocity and acceleration. I found that Kalman filter worked well, but I then asked myself what's the difference between this and just doing a moving average? I found that if I used a window of about 10 sam... | 41,547 |
<p>This question deals with an example of image reconstruction related to <a href="http://stats.stackexchange.com/questions/62280/example-of-signal-reconstruction?rq=1">this other question</a> on signal reconstruction. I have different issues in both examples but there could be an underlying factor.</p>
<p>I tried to ... | 31 |
<p>I have many measures of Y for two groups A and B. Following the more modern approach of research in education, I calculated the effect size of the difference of Y for both groups (Cohen's d), and the significant interval for the effect size.</p>
<p>The fact that the effect size was positive and significant (both in... | 31,160 |
<p>I'm trying to write such likelihood using JAGS in <code>R</code> (in order to estimate parameters $\xi$ and $\pi$, being $m$ fixed equal 7) using the "ones trick" and got stuck in defining the binomial coefficient (<code>term3</code>). How would you define the binomial coefficient?
$$
P(Y=y)=\left\{
\pi\binom{m-... | 31,162 |
<p>Consider me a "naive researcher." </p>
<p>We have a test of 25 items grouped into 5 item types. Each item is correct or incorrect. All items are math questions, but we expected 4 item types to have different language confounds. We have a population of 28 group A and 32 group B. We expected group A to under perform ... | 41,651 |
<p>My textbook puts this in a sidebox with the heading "Note" and doesn't explain why. Could you tell me why this statement holds?</p>
<p>$P(a < Z < b) = P(a \leq Z < b) = P(a < Z \leq b) = P(a \leq Z \leq b)$ </p> | 70,291 |
<p>I have a set of ordinal data, generated by a hypothetical turing machine. The data consists of a sequence of symbols such as:</p>
<pre><code>LB1, LB2, UU, UB1 ...
</code></pre>
<p>The labels have a natural ordering, and the machine "prints" out the symbols at an irregular pace. </p>
<p>I would like to analyze, fo... | 70,292 |
<p>How is $1/T$ distributed if $T$ follows a <a href="http://en.wikipedia.org/wiki/Student%27s_t-distribution" rel="nofollow">Student's $t$-distribution</a>?</p> | 70,293 |
<p>After writing this post, I've realized that I am running around in circles, chasing my tail. Any help approaching this problem would be greatly appreciated, as I think I just need to bounce ideas around and don't have colleagues that can help with statistical methods at my new position.</p>
<p>I am working on an in... | 70,294 |
<p>I have written some code that can do Kalman filtering (using a number of different Kalman-type filters [Information Filter et al.]) for Linear Gaussian State Space Analysis for an n-dimensional state vector. </p>
<p>Let us consider the linear Gaussian State Space model </p>
<p>$$y_t = \mathbf{Z}_{t}\alpha_{t} + \e... | 70,295 |
<p>For work, I'm working on an app where you essentially forecast the failure rate of the overall machine through different factors such as the historical failure rates for the components used to build it or the failure rates of the factories that manufacture it, or even the historical rate for the machine itself. The ... | 70,296 |
<p>I have a 4x2 table that I want to do a Cochran-Armitage trend test for. Basically, I want to test for lack of independence as the dose (the rows) increase.</p>
<p>I'm trying to figure out the R code but am having some trouble. As there's no clear documentation in the coin package. What's more my rows are not linear... | 31,174 |
<p>I am having trouble understanding what exactly R is outputting when I look at the coefficient summary for the full model.</p>
<p>For the lowbwt data, there are 4 variables: low, age, lwt, race (3 levels), and ftv. Low is the binary response variable.</p>
<p>For example, if I am testing H0: beta_lwt=0 vs H1: beta_l... | 70,297 |
<p>Approach 1:</p>
<pre><code>lm.fit <- glm(response ~ 1, offset=log(lam), family="quasipoisson")
summary(lm.fit)
</code></pre>
<p>Approach 2: Feed summary.glm with a pearson dispersion.</p>
<pre><code>lm.fit <- glm(response ~ 1, offset=log(lam), family="poisson")
summary(lm.fit,
dispersion=sum(residua... | 31,176 |
<p>How can I convert predicted probabilities of a logit model into predicted binary response ? Can I consider 0.5 as cut point to convert probabilities to binary variable (0,1).
Or should I use binomial distribution to generate binary variable where predicted probabilities are used as success probability. By the way ... | 70,298 |
<p>I have four groups with six subjects in each group. For each subject I have measured their mean blood pressure every minute for 3 hours. This means that I have 180 variables.
The first 60 minutes represent "baseline" blood pressure, the next 60 minutes represent an intervention, and the last 60 minutes represents re... | 36,280 |
<p>I have found the following very useful theorem and I would appreciate some help comprehending it fully.</p>
<p><strong>Theorem</strong> Let $\{X_n \} $ be a sequence of random variables bounded in probability and let $ \{Y_n \} $ be a sequence of RVs which converge to $0$ in probability. Then</p>
<p>$$X_n Y_n \ri... | 70,299 |
<p>I have some data which can be modelled as such: each data sample $S$ is a series of discrete signal values $S(t_n) \in \{-1, 1\}$ measured at times $(t_{n, S})_{1 \leq n \leq N_S}$. The number of signal measurements $N_S$ per sample and the times at which the measurements were made all vary from sample to sample: $N... | 70,300 |
<p>I am going to analyze some data for an intermittent operation using R. Let's say I operate a Xmas tree stand from Black Friday to Christmas Eve every year. Let's say I operate 150 different Xmas tree stands every year. Let's say I have data for revenue-per-day for these 150 Xmas tree stands for the last 6 years. I w... | 44,895 |
<p>I want to predict a continuous variable from text features. Lets say I have some student essays and I want to predict their quality, as measured by a human grader, using text features (mostly words they use). </p>
<p>Linear regression is an obvious candidate, but if I have substantially more features than graded es... | 70,301 |
<p>I call these "tweaker" variables -- the ones that pass some statistical test for inclusion, but whose contribution is minimal -- but I'm looking for a better or established label. </p> | 31,185 |
<p>I used some categorical variables as predictors to a negative binomial model. The dependent variable is numerical. I used glm.nb in R and the results show relative coefficients of one category respective to another category.</p>
<p>Then I tried using lm.beta to standardize the coefficients, but still the results ar... | 31,187 |
<p>suppose you might buy some software to be used in a ML/NLP/DM laboratory. What software package would you ask for? Let's say: MATLAB (with some toolboxes), SPSS, and what else?</p>
<p>I know that there is a lot of free software one can use like R, Weka, Rapidminer, python packages, and so on. However, the above que... | 70,302 |
<p>Can somebody explain me clear the mathematical logic that would link two statements (a) and (b) together? Let us have a set of values (some distribution). Now,</p>
<p>a) Median does not depend on every value [it just depends on one or two middle values];
b) Median is the locus of minimal sum-of-absolute-deviations ... | 70,303 |
<p>Jeffrey Wooldridge in his <em>Econometric Analysis of Cross Section and Panel Data</em> (page 357) says that the empirical Hessian "is not guaranteed to be positive definite, or even positive semidefinite, for the particular sample we are working with.".</p>
<p>This seems wrong to me as (numerical problems apart) t... | 49,855 |
<p>I would like to solve for $\pi$1 in equation 7.14 of Hayes and Moulton's "Cluster Randomized Trials". I can't for the life of me remember how to do so. Here is a <a href="https://www.dropbox.com/s/a64q7vy97m6rv1e/hm714.jpg" rel="nofollow">link</a> to the equation.</p>
<p>Here is the R script I wrote to calculate c ... | 70,304 |
<p>I have <a href="http://en.wikipedia.org/wiki/Case_fatality_rate" rel="nofollow">Case Fatality Rates</a> (deaths per 100 cases) for 2 different states receiving different treatments for 17 years.</p>
<p>What is the best statistical method to compare Case Fatality Rates ?</p>
<p>The data are like this</p>
<pre><cod... | 70,305 |
<p>The Wing-Kristofferson model is a simple model of the behavior of a human trying to drum out a steady beat (that is, trying to mimic a metronome). Let $y_i$ be the $i$th interval between two drum beats then the model is:</p>
<p>$$y_i \sim \text{Normal}(\mu + m_i - m_{i-1}, \sigma_y) $$
$$m_i \sim \text{Normal}(0, \... | 31,198 |
<p>I've to draw a polygon which will join the four vertexes on the plot in <em>R</em>. For this I need<br>
minimum value of X which has minimum Y value. </p>
<pre><code>X <- c(-62, -40, 9, 13, 26, 27, 27)
Y <- c( 7, -14, 10, 9, -8, -16, 12)
plot(x = X, y = Y)
abline(h = 0, v = 0, lty = 2.5, col = "gr... | 70,306 |
<p>I have 54 names.</p>
<p>I would like to know how many unique combinations of 6 names I can create, where at least 2 of the names are different from those in every other combination?</p>
<p>My maths is extremely rusty but I understand how to calculate the number of unique combinations.</p>
<p>I also understand how... | 31,199 |
<p>As far as I know, one can differentiate between two main goals of the regression analysis:</p>
<ol>
<li><p>The goal is understanding causal relations between variables. Here, one has to check several common regression assumptions (main being linearity, normality, residuals zero mean, homoscedasticity, independence ... | 70,307 |
<p><a href="http://en.wikipedia.org/wiki/Effect_size">Wikipedia</a> says </p>
<blockquote>
<p>effect size is a measure of the strength of a phenomenon or a sample-based estimate of that quantity. An effect size calculated from data is a descriptive statistic that conveys the estimated magnitude of a relationship wi... | 70,308 |
<p>I want to obtain the full distribution of a Gamma (or Inverse Gaussian) distributed $y_i$ given a vector of $\bar x_i$ that have been used in the linear predictor of a coefficient. Suppose also for the Gamma GLM I have used the log-link instead of the canonical link.</p>
<p>Since both distributions are bi-parametri... | 70,309 |
<p>I have two painkillers and I have given them to two groups and recorded how the pain level changed in three categories: "Helped a lot", "Slightly better", "Did not help"</p>
<p>Now I want to do a t-test and I was planning to convert each label to a number (say 3,2,1) and run a t-test on those numbers to see if any... | 70,310 |
<p>I have collected spatial data (GPS points and foraging heights) for a bunch of territorial animals. Until recently, these types of data were only analyzed in two dimensions (2D). However, 3D analysis is now available and I'm working on a paper that compares 2D and 3D estimates of spatial overlap. I define spatial ov... | 70,311 |
<p>how can one handle a time series with the Chow's test (in order to find a structural break) so that the assumption of independent model errors holds? I'm using the R function chow.test {gap}</p> | 47,995 |
<p>I am studying the correlation between a set of input variables and a response variable, price. These are all in time series.</p>
<p>1) Is it necessary that I smooth out the curve where the input variable is cyclical (autoregressive)? If so, how?</p>
<p>2) Once a correlation is established, I would like to quantify... | 70,312 |
<p>In a predictive model, I have standardized variables as predictors. Say I have to rescore the model on fresh data at some point in the future: do I use the means/stds as they were when I built the model to center and scale the new data, or do I use the means/stds as they are with the data I'm scoring.</p>
<p>My tak... | 70,313 |
<p>I am reading this example, but could you explain a little more. I don't get the part where it says "then we Normalize"... I know</p>
<pre><code>P(sun) * P(F=bad|sun) = 0.7*0.2 = 0.14
P(rain)* P(F=bad|rain) = 0.3*0.9 = 0.27
</code></pre>
<p>But where do they get</p>
<pre><code>W P(W | F=bad)
-----------------... | 41,710 |
<p>I have $n$ error measures that can be positive or negative values. Negative values are more important for my experiment than positive values. Of course, taking the mean of the $n$ values doesn't make sense because the mean could be $0$ and that won't reflect in one number what is happening. What summary statistic ca... | 31,211 |
<p>I have seven factor and one response variable with 32 run and one replication i.e. 64 runs and I want to use logistics regression. I found in th analysis that 4 out 7 factors are significant. I want to check curvature. If curvature is not significant then should i make some other lay out of DoE only considering only... | 70,314 |
<p>In Gradient Boosted Regression Trees, a shrinkage $\nu$ is often applied as:
$$ f_t(x) \leftarrow f_{t-1}(x) + \nu h(x)$$
where $h$ is the regression tree learned by fitting the tree to the gradient. I've tried implementing this and found that this shrinkage is indeed necessary to prevent overfitting. The shrinkage ... | 70,315 |
<p>I am trying to create a forest plot for a small sample of case series. As the studies are case series there is only an experimental group, no control group. I would like to use event rate and sample size for each of the studies to create the graph. I am having difficulty as most software requires you input data f... | 31,215 |
<p>I have heard of this term </p>
<p>supossing I have a matrix like</p>
<p>$\begin{bmatrix}
1 & 12 & 13 & 14 \\
2 & 22 & 23 & 24 \\
3 & 32 & 33 & 34 \\
4 & 42 & 43 & 44\\
5 & 52 & 53& 54
\end{bmatrix}$</p>
<p>I count the number of rows $n$ wich ... | 31,216 |
<p>I am working on a stopping rule for an optimization algorithm that produces an upper bound and lower bound for the objective value of an optimization problem. In my case, the lower bound is deterministic, but the upper bound is an estimate derived from $N$ data points $UB_1, UB_2... UB_N$ with mean $\widehat{UB}$ an... | 70,316 |
<p>I have been reading about calculating R2 values in mixed models and after reading the R-sig FAQ, other posts on this forum (I would link a few but I don't have enough reputation) and several other references I understand that using R2 values in the context of mixed models is complicated. </p>
<p>However, I have rec... | 70,317 |
<p>I admit I'm relatively new to propensity scores and causal analysis.</p>
<p>One thing that's not obvious to me as a newcomer is how the "balancing" using propensity scores is mathematically different from what happens when we add covariates in a regression? What's different about the operation, and why is it (or is... | 70,318 |
<p>I would like to perform column-wise normalization of a matrix in R. Given a matrix <code>m</code>, I want to normalize each column by dividing each element by the sum of the column. One (hackish) way to do this is as follows:</p>
<pre><code>m / t(replicate(nrow(m), colSums(m)))
</code></pre>
<p>Is there a more suc... | 70,319 |
<p>Good evening everyone, I am attempting a self-study question on probability and am faced with one which really quizzed me.</p>
<blockquote>
<p>A study found that a family typically spends between \$500 and \$4500 a month on expenses. Suppose the money spent is uniformly distributed between these amounts. If we ra... | 70,320 |
<p>I have about 50-100 million rows of data of interesting "events". Each of these rows has about 32 attributes. One of these attributes is how much money we made :-)</p>
<p>What's the best way to make sense of this data? I've heard that Decision trees might be a great way to understand this.</p>
<p>To be clear, I do... | 70,321 |
<p>Good evening everyone,</p>
<p>I am currently working on a self-study question:</p>
<blockquote>
<p>There is 15 marbles in a jar. Six are blue, while the rest are green. Five random marbles are selected. What is the probability that the number of blue marbles selected is more than the number of green marbles sele... | 70,322 |
<p>I am currently doing a self-study on Conditional Probability. I was faced with a question where I was provided with $P(a)$, $P(b)$, $P(c)$, $P(a \mid d)$, $P(b \mid d)$ and $P(c \mid d)$.</p>
<p>The full context of the question:</p>
<blockquote>
<p>A departmental store reports that 30% of payment is collected in... | 70,323 |
<p>I have 15 factors which I want to optimize. Instead of running a fractional factorial design consisting of 32 runs, if I run a design consisting of 16 runs, will I only get main effects or any second order interactions too? </p>
<p>I am sure that there are no third order int. but maybe 1 second order interaction wi... | 70,324 |
<p>I am performing a market basket analysis of customers and the products they purchased. I did an a priori analysis on all of the transactions on the products they purchased to determine which items are likely bought together.</p>
<p>I have additional attributes (industry, geography, etc.) about the customers (B2B),... | 70,325 |
<p>I'm working to find the best C and gamma values for the RBF on my dataset using an SVM classifier. Specifically, I'm using LibSVM & MATLAB. </p>
<pre><code>g=[2e-5,2e-4,2e-3,2e-2,2e- 1,2e0,2e1,2e2,2e3,2e4,2e5,2e6,2e7,2e8,2e9,2e10,2e11,2e12,2e13,2e14,2e15];
C=g';
matrix_gC_aust=zeros(21,21);
matrix_gC_germ=zero... | 31,224 |
<p>I am trying to calculate the reliability in an elicitation exercise by analysing some test-retest questions given to the experts. The experts elicited a series of probability distributions which were then compared with the true value (found at a later date) by computing the standardized quadratic scores. These score... | 70,326 |
<p>I've got a linear regression model with the sample and variable observations and I want to know:</p>
<ol>
<li>Whether a specific variable is significant enough to remain included in the model.</li>
<li>Whether another variable (with observations) ought to be included in the model.</li>
</ol>
<p>Which statistics ca... | 70,327 |
<p>A colleague wants to compare models that use either a Gaussian distribution or a uniform distribution and for other reasons needs the standard devation of these two distributions to be equal. In R I can do a simulation...</p>
<pre><code>sd(runif(100000000))
sd(runif(100000000,min=0,max=2))
</code></pre>
<p>and se... | 70,328 |
<p>I have the following type of dataset:</p>
<pre>
| | | variable_r |
subject | gender | age_group | Cond_1 | Cond_2 |
--------|----------|-------------|---------------|---------------|
1 | m | 1 | r (A) | r (B) | r (A) | r (B) |
... | 31,237 |
<p>I have a mixed ANOVA with one between and one within factor:</p>
<p>between factor: control versus treament </p>
<p>within factor: ad1, ad2 (measures click rates on 2 ads)</p>
<pre><code>aov(repdat~(within*between)+Error(subjcts/(withincontrasts))+(between),data.rep)
</code></pre>
<p>However my outcome repdat ha... | 31,239 |
<p>I'd like to regress a vector B against each of the columns in a matrix A. This is trivial if there are no missing data, but if matrix A contains missing values, then my regression against A is constrained to include only rows where all values are present (the default <em>na.omit</em> behavior). This produces incorre... | 31,241 |
<p>I am performing this simple experiment: I have one variety of grass and 8 different fungi (say #1 to #8). I am going to put 10-20 grass plants in each one of 18 containers, and then I will put each one of the fungi in 2 containers and let 2 with no fungus ("negative control"). After some time I will count how many p... | 31,242 |
<p>Following my question <a href="http://stats.stackexchange.com/questions/28199/wide-or-narrow-confidence-interval">here</a>, I am also looking at the difference between males and females and I have conducted linear regression in a general linear model setup for this purpose.</p>
<p>My effect size for this part of th... | 45,796 |
<p>I was wondering how to get arguments for <em>R</em> functions. Is there any <em>R</em> function which can be used to get all arguments for a certain function?</p>
<p>As <em>R</em> function glm has the following arguments</p>
<pre><code>glm(formula, family = gaussian, data, weights, subset,
na.action, start = NULL,... | 70,329 |
<p>Is it ever valid to include a two-way interaction in a model without including the main effects? What if your hypothesis is only about the interaction, do you still need to include the main effects?</p> | 49,299 |
<p>I made a comparison of hatch success between 2 populations of birds using R's <code>prop.test()</code> function:</p>
<pre><code>prop.test(c(#hatched_site1, #hatched_site2),c(#laid_site1, #laid_site2))
</code></pre>
<p>It gave me the proportions of each site as part of the summary. How can I calculate the standard ... | 70,330 |
<p>I have data sample size of almost 15,000 cases. The dependent variable is a dichotomous variable stating whether the patient has the disease or not, Yes=1, and No=0. I have 12 more independent variables which are continuous as well as dichotomous. My question here is, before I apply the logistic regression, I need t... | 70,331 |
<p>I hate talking about "outliers," because I view that term as encompassing two entirely different concepts. The first is when it refers to data that was incorrectly recorded or measured. For instance, a <a href="http://stats.stackexchange.com/a/7158/2485">400000 bedroom house for 4 dollars</a> or a person that is 1... | 70,332 |
<p>I am simulating two loaded dice and trying to estimate individual die prior probabilities and probability mass functions for each of them using the EM algorithm.</p>
<p>Below is my Matlab code. Likelihood and pmf values remain constant second iteration onwards. Why is that?</p>
<pre><code>% dice pmfs pmf1 and pmf2... | 70,333 |
<p>I recently came across the distribution $U(\theta, k \theta)$ (where k is known) in the context of statistical theory (as a nice toy example for finding MLE and the likes).</p>
<p>However, I was wondering if there are real use cases where one might wish to use this distribution for modelling something. But I couldn... | 70,334 |
<p>I'm in the middle of analyzing data taken from testing two different ISP connections (cable and DSL). I've been running randomized testing on the two connection using three different tests which all measure the same basic thing: connection time (ms) and Download Speed (Mbit/s). Some of the tests also record Upload... | 70,335 |
<p>I am facing some problems concerning which statistical approach to use for my measurements.
I have a sensors which counts how many times an events occured. I had to characterize two lots of sensors, and I tested 10 devices per lot.</p>
<p>Each time I tested a sensor I collected more then 6000 counts in order to red... | 56 |
<p>I want to compare different Arellano-Bond models, but I don't know exactly how to do it and which statistics to consider. For instance, should I compare $\chi^2$ of Sargan tests? What other options exist?</p>
<p>PS: I am using <code>pggm</code> in <code>R</code> to fit models.</p> | 70,336 |
<p>I'm looking for an example of a data set that can be fitted using a GLMM with at least 3 separate random effects. I've taken a look at a few books on GLMM's including the one by McCulloch and Searle, but their examples always stop at 2 random effects. I don't know why I'm having so much trouble wrapping my head arou... | 41,754 |
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