# All Questions

2 views

### Use full or reduced model to identify significant variables to then determine pairwise differences?

I have a hypothesis testing model in which I would like to know if environmental variables I collected influences the probability a bacteria on a given amphibian kills a pathogen. Following ...
9 views

### Overfitting with Linear Classifiers

Today our professor stated in class that "overfitting with linear classifiers is not possible". I hold that to be wrong, since even linear classifiers can be sensitive to outliers in the training set ...
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### Specifying a random effects model. The effect of age depends on lab?

Four different labs record different subjects' reaction times repeatedly (without them getting older or changing gender). I assume reaction time will depend on age, gender, subject, and lab. I want to ...
7 views

### Re-weighting a survey after resampling with replacement been already used

I'd love to hear some experts' advice on a survey I'm working on. Let's assume a survey being conducted on a sample of community organizations. A public database (the sample frame, but almost a ...
10 views

### Ranking data based on several data points

I'm looking to take fantasy football projection data and use it, in combination with a couple of other factors, to rank each player. I am collecting player score projection and ranking data from a ...
5 views

### finding maximum depth of random forest given the number of features

How do we find maximum depth of Random Forest if we know the number of features ? This is needed for regularizing random forest classifier.
6 views

### ANCOVA where slopes are not different

I have an observational experiment, with two groups measured before and after treatment. I'm using an ANCOVA analysis, but the assumption of independence in slopes is not met - ie the slopes are the ...
12 views

### What data analysis technique should I use?

I am seeking to confirm that staff members are more likely to perform pro-environmental behaviour if they perceive support from their manager. The behaviours are measured by an ordinal scale (very ...
13 views

### Relation between linear regression prediction accuracy and correlation

This question is more of theoretical. I am not sure if this is the right place, but still giving it a try. I have two variables - direct cost and indirect cost. When salespersons go for sales pitch ...
8 views

### Pooling unequal numbers of survey years

I am analyzing how health insurance disparities changed following January 1, 2014, using a large, nationally representative survey with complex design. I have access to many years of data but 2014 is ...
12 views

### What is an appropriate machine learning model for a dice game?

I'm having trouble thinking of the correct way to pose the following problem: Say a dice game (like Yahtzee) involves throwing up to 5 6-sided die in three rounds. After three rounds, a score is ...
10 views

### multinomial proportion confidence interval

Is there any difference between the multinomial confidence interval for proportions and the binomial confidence interval for proportions, or do I just compute pj for j binary variables in the same ...
11 views

### What panel data regression model to be adopted

I am working on a panel data comprising of n=253 and t=10. I wanted to find out the impact of 8 IDV on a DV. My some IDV are in ratio, some in numbers and some are dichotomous. My DV is in ratio. When ...
6 views

### DLNM and crossreduce(): getting the coefficients behind the cross-basis

I am using the R package dlnm to fit a distributed lag non-linear model estimated with lm(). One can specify both the exposure ...
19 views

### Why the probability in my logistic regression is far from 0.5 in R?

Logistic regression models the relationship between a set of independent variables and the probability that a case is a member of one of the categories of the dependent variable. If the probability is ...
14 views

### KDD 15 paper: scoring bigrams

I am by no mean into Statistics nor NLP. And I am reading the following paper, trying to learn something new: ...
17 views

### Joint Probability Table and Dependent/Independent Probabilities

Can someone help me? I think that i misunderstood the concept of joint probabilities for independent and dependent events. I understand that for independent events we can just multiply each random ...
16 views

### Maximum Likelihood Estimation (MLE) [duplicate]

I need help about MLE. I made a lot of research for this topic but never found a real world example for understanding the purpose of this bull...t. I know that MLE is used for approximating params for ...
6 views

### Normality identifier in Shapiro-Wilk test

When using the Shapiro-Wilk test, should I look at the p-values or the W values in order to find out the "most" normal value among my different samples (e.g. iq, age, weight -- if I'm running ...
61 views

### Going from daily probability to annual rate: more complicated than I thought?

I am trying to go from a functional relationship between a predictor variable and a probability of an event occurring ($P = f(X)$) to an overall rate at which the event occurs. My scenario is ...
22 views

### Can we save the Random Forest model output in R and use it to score data in the future? [on hold]

i am new to R and i have been exploring to use Random Forest to predict if a person will open an email or not. so i did run a random forest tree and scored a test data set. i wanted to know if i can ...
16 views

### Small Point Set Matching

I'm trying to match two small sets of points (~10 each) and can't find a particularly successful algorithm. All points have a known co-variance matrix and are only 2D. Many points in each set are ...
11 views

### How much should lags be used in GMM?

what are the necessary conditions for the use of lags in GMM and to what extant the lags should be use? is there any limit for the lags in GMM? i know its pretty question but due to my limited ...
11 views

### Why error rate converges faster if the visiting order of mini-batches are changed at each epoch?

I'm quoting from the paper: As for any stochastic gradient descent method (including the mini-batch case), it is important for efficiency of the estimator that each example or minibatch be ...
11 views

### Bayesian Updating Informed Data Prior, reducing its affect/weight by reducing its precision?

thank you for reading my question and helping if possible. What I have done so far: I have two datasets of times to failures, Data A and Data B, which both follow a log-normal distribution. Data B ...
10 views

### Multi-class classification problems

I have a dataset which consists of nominal as well as categorical data. I have to classify data into 5 different classes. The data is very unclean with many missing values for certain fields in the ...
21 views

### Mean and residual centering, orthogonal polynomials and effect coding

I understand that in order to be able to interpret main effects / lower order terms in a more intuitive way in linear regression models with interaction effects one should either use mean or residual ...
33 views

### Question on statistics formulation

I'm been wondering about this for a while. Given the probability, p, the probability after N times is ...
7 views

### How to plot error ellipse knowing the VCV for xx,xy,xz,yy,yz,zz

I would love some guidance on if it is possible to plot error ellipses knowing what the title says and how to do it. The data has to do with GPS measurements and I need the error ellipses to find the ...
26 views

### Bayesian Logistic Regression ? Why?

I have data from a trial, I can't go to clinical details, so I will describe the way the data is gathered, and we'll just accept it as a fact I have to deal with. Every patient is being treated with ...
23 views

### If I have a k-dimensional random vector distributed as multivariate gaussian, are the elements of the random vector also gaussian?

Suppose I have a $k$-dimensional random vector $X\sim N(\mu,\Sigma)$, where $\mu$ is the mean vector and $\Sigma$ the covariance matrix. Is the $i$-th element of $X$ also distributed as a gaussian ...
16 views

### How does or can a GLM incorporate prevalence?

I am comparing a presence/absence (binomial GLM) in R with a presence-only (Maxent) species distribution model. In Maxent, you can easily specify the prevalence of your species. I am using ...
23 views

### when to analyze full data set vs. residuals

Say I have a data set, and I want to model the dependent variable y, as a function of x1,...
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### If y=f(x̄), in which x̄ is the mean of xi, how can I calculate the minimum number of x samples to obtain y with 95% confidence and 10% error? [duplicate]

I am able to calculate the minimum number of samples of x based on the standard deviation of x and the assumption of normal distribution using the standard equation. However, I need to know what that ...
14 views

### Histogram for the first 1000 observations in a .csv file in R [on hold]

I have a dataset of 2000 observations with different columns, I wish to plot a histogram for the first 1000 rows and a different histogram for the second 1000 rows. How can I do that? Alternatively, ...
6 views

### Thiele's differential equation [on hold]

When derives Thiele differential equation, why do they? Why not just use the value function directly? My question is, why not use the expected insurance payments minus the expected future premiums, ...
4 views

### Confidence bound for multi-label classification

suppose I have an algorithm for classifying an input vector into one of a discrete set of labels. I would like to assess the performance of the algorithm by comparing its results to a manually ...
13 views

### Assign a sample to one of two populations, based on a set of measurements with missing data

I apologize if this is a simple question but I cannot figure out the following: In my dataframe df I would like to know if ...
11 views

### Appropriate distance measure

I'm working with a dataset containing 600 matrices (dim: 44x3) with numerical results of applied tests (pass, fail, toVerify). Data is organized in rows. Row nr 1 represents test nr 1. Tests can be ...
188 views

### How to best evaluate a time series prediction algorithm?

What's best-practice for training and evaluating a prediction algorithm on a time series? For learning algorithms that are trained in batch mode, a naive programmer might give the raw dataset of ...
9 views

### GMM or Gaussian Copula

Lets say I have 5 clusters each having 20 entires multivariate data (X,Y). I computed the mean and covariances for these clusters. To describe the underlying probability distribution of the whole data ...
15 views

### How to calculate the variance of the output variable of a function based on the input variable?

I am able to calculate the minimum number of samples of x based on the standard deviation of x and the assumption of normal distribution using the standard equation. However, I need to know what that ...
8 views

### Optimum path through an evolving graph (cell grid)

I have a 2D grid which an agent can pass through. At each time step, the agent must move to any adjacent square (including diagonals). Each cell has a weight assigned to it. This distribution of ...
14 views

### Which transformation to apply on a skewed distribution?

Should each feature be transformed to a normal distribution in each and every case or it depends on the classifier or other factors ? First of all how do we conclude that data is skewed and if it is ...
12 views

### Install packages in R via install.package() is secure? [on hold]

So, in some times when i will install any package in Rstudio, i get this error: some_package has non-zero exists Then, i have to resort install packages via ...
15 views

### Does “level” in exponential smoothing stand for the “mean”?

In triple exponential smoothing it is said that there are estimates for 3 components: level, trend and seasonal. Does "level" here stand for "mean"? In single exponential smoothing is only the level ...
27 views

### Which person to include in Ph.D dissertation committee? [on hold]

I have a problem here... I am working in research field A in Economics, and I want to include a professor who is in field B in Economics. I used to work with this professor and know him well. I'm ...
11 views

### Tell Stata to ignore missing values when adding variables [on hold]

I want to create a new variable in Stata, that is a function of let's say 3 different variables, A, B and C, like so: gen new_var = ((A)/3) + ((B)/2) + ((C)/4) All observations have missing values ...