# All Questions

2 views

### Power analysis for spatially structured variables in survival analysis

I am working with colleagues on an analysis of survival in a chronic neurological disease. There are several well known factors that influence survival. We have data from a good register which ...
5 views

### Ratio between training error and validation error

I know that we should choose the model which minimizes validation error. But is there any meaning of ratio between training error and validation error?
15 views

### Difference in Difference with control - common trend interpretation

I have a question concerning the interpretation of the common trend assumption in a very specific case of diff-in-diff. I am using a panel to find the effect of a treatment (on houesehold level) on ...
8 views

### Compare values on a logarithmic scale

how to compare values on a logarithmic scale? I was working on a research paper, and evaluated few results in logarithmic scale (dB). i want to compare the results with existing algorithm. the problem ...
12 views

### Conditions to be in a class of Poisson distribution

A discrete random variable $X$ follows a Poisson distribution. The first $100$ values of $X$ are $x_1,x_2,x_3,....,x_{100}$ with rate parameter $\lambda_{100}$. $G_{\lambda_{100}}$ is a set of all ...
8 views

### Intuitive explanations of differences between Gradient Boosting Trees (GBM) & Adaboost

I'm trying to understand the differences between GBM & Adaboost. These are what I've understood so far: There are both boosting algorithms, which learns from previous model's errors and ...
5 views

### Multiple event for segmented regression?

Is there any statistical methods like segmented regression for many(>3) events? Recently, many policies in my field were introduced in a short period of time. I usually used segmented regression to ...
6 views

### Distribution of sum of negative binomial parametrized with mean and aggregation parameter

From textbook, I know that: If each $X_i$ is distributed as negative binomial $(r_i,p)$ then $\sum X_i$ is distributed as negative binomial $(\sum r_i ,p)$. In R: ...
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### Selecting the best GLM (generalized linear model)

GLM (family=binomial) is foucusd on when the response is dichotomous(yes/no, male/female, etc..). I'm wondering how to judge if the model we built is good eough? As we know, in OLS regression some ...
6 views

### For classification w unbalanced datasets, is class-weighing the same as oversampling?

in unbalanced classification problems, I find myself using class_weigh = "auto" or similar parameters often, but I don't think I'm fully understanding what it's doing. I know that it's the industry ...
15 views

### How probable a distribution belong to a collection of distribution?

How can I check that a empirical distribution function belong to a group of empirical distribution functions?
12 views

### Proof of LOOCV formula

From An Introduction to Statistical Learning by James et al., the leave-one-out cross-validation (LOOCV) estimate is defined by $$\text{CV}_{(n)} = \dfrac{1}{n}\sum\limits_{i=1}^{n}\text{MSE}_i$$ ...
19 views

### joint probability distribution of $k \le n$ order statistics

For $1\le r_1 < ..<r_k \le n$ integers, I am trying to find the joint pdf of: $$(X_{(r_1)},...,X_{(r_n)})$$ where $X_{(r_1)}$ is the $r_1$th largest observation. I am wondering if anyone has ...
6 views

### # of free parameters in AIC for grid search like threshold model

I need to compare fit of two models. They are dose-response function with Poisson regression framework. Model 1 y=bx Model 2 y=0 if x is less than x0 bx otherwise (x0=0,1,2,...) For model ...
13 views

### Simulate data around existing data in r

I have been working at this for sometime, surfing StackExchange and any other R webpage I can find without any luck. I am trying to simulate data to essentially recreate the attached figure with ...
3 views

### Multiple tests, summary of clogit

I have 10 exposure variables that i would like to analyze univariate. I've applied the conditional logistic regression model for each exposure and then used the summary function for each one of them. ...
16 views

### What is the limiting distribution of the Bayesian Filtering

I've got a question about the iterative Bayesian filtering, the general form of which is shown as follows: $P(x|z_0,...z_{k+1})\propto P(z_{n+1}|x)P(x|z_0,...,z_k),\,k=0,1,\dots$. $P(x|z_0)=P_0(x)$ ...
22 views

### Using predict with PCR in R

I'm trying to follow the documentation on the pcr method in R So I do the following ...
19 views

### Shrinkage of the Sample Covariance matrix

Assume we have N independent and identically distributed random vectors $X_1, X_2, ..., X_N$ where each of them is of size p $\times$ 1. The sample covariance matrix, denoted here by $S$, is computed ...
16 views

### Difference scores in linear mixed models?

I have a question about how to interpret fixed effect interaction coefficients, which appear to be difference scores, in linear mixed models using SPSS. I am looking at the consistency of ...
18 views

### Calculate Var(X/Y) for dependent variables?

I understand that you can calculate Var(X*Y) through Bienayme, whether variables are dependent or not. I am wondering if there is a similar way of calculating Var(X/Y) when variables are dependent? ...
21 views

### Why are Hinton's multilayer deep-learning networks stochastic?

First I'll sum up my intuitive (beginner) understanding of his deep-learning architecture. A short summary can be listened to on Coursera in the 5 minute video. We start with several layers of ...
10 views

### What can be deduced from the variance and cramer rao bound?

I have computed the cramer rao bound of the estimates of the coefficients $\mathbf{h^T}$ for a moving average model (MA) involving 2 different process noise : (1) when the process noise is a random ...
9 views

### Relationship: Regression Coeffecient and Line Plot Trendline Slope

Why does the slope of my line fit plot not match the coefficient of the same variable in my regression? For one of the variables, the coefficient is positive while the line fit plots trendline is ...
7 views

### MLR, should all interactions be included even when irrelevant for tested hypothesis?

I have two simple questions yet I could not find a direct answer to either of them, so I would be thankful to anyone who could help me. I have 3 independent variables, X, Z and Q, where X is ...
12 views

### sample size of infinite population and alternative comparisson

I need to compare two alternative methods of manufacturing a product, say A and B. I wanted first to dermine the sample size of ...
15 views

### Do I need to categorize likert responses so I can use logistic regression?

I'm conducting a research project to evaluate burnout level among critical care nurses and whether this level can be related to other variables (age, workload, unit, etc). Burnout level is measured ...
22 views

### How to compare (probability) predictive ability of models developed from logistic regression?

I know some well-known measures are $c$ statistic, Kolmogorov-Smirnov $D$ statistic. However, as far as I know, those statistics take into account only of the rank order of the observations, and is ...
24 views

### How do I use weight vector of SVM and logistic regression for feature importance?

I have trained a SVM and logistic regression classifier on my dataset for binary classification. Both classifier provide a weight vector which is of the size of the number of features. I can use this ...
15 views

### Marketing analytics texts

Can you recommend a comprehensive textbook or a monograph on marketing analytics? I'm interested in metrics, measures and statistical methods used in the field. For instance, what are the approaches ...
13 views

### Coding factors with non-numeric settings

For my role as a TA I am assisting the instructor in developing curriculum based on DOE and statistics. We have a set of failure strengths (the output/dependent variable) for several glass rods. The ...
21 views

### FONT Problem: SAS Enterprise guide 6.1 on Windows 10 [on hold]

Today, I installed Windows 10 on my new computer. Then I installed SAS 9.4 M1, included SAS Enterprise guide 6.1M1. However, the program window's font in SAS Enterprise guide looks awkward. Fonts ...
7 views

### How to separate “rates” with TukeyHSD?

My data is formated as Treatment and Cultivar, which are factors, and GDD, which is a continuous variable. The response variable is DTA_R, so my model is basically glm(DTA_R~TreatmentCultivarGDD). I'm ...
12 views

### Multivariate Regression Analysis in SPSS

I am using SPSS to perform a multivariate regression analysis. I have 4 factors, Group (1,2), AgeGroup (1,2), Sex (0,1), and handedness (0.1) with 4 dependent variables. My question relates to ...
9 views

### How does one call external datasets into scikit-learn? [migrated]

For example consider this dataset : (1) https://archive.ics.uci.edu/ml/machine-learning-databases/annealing/anneal.data or (2) http://data.worldbank.org/topic How does one call such external ...
12 views

### Encode special values in continous predictors

I have continuous variable with missing values. Missing values are of different types (indicated by special values such as 991, 992). How do I best encode my data for logistic regression? I can create ...
49 views

### Cohens d effect sizes

I'm using Cohens d effect sizes as a means of providing a magnitude based inference in a study I'm conducting. I just wanted to clarify if I'm correct here: Anything between .0 and .2 is small. ...
9 views

### How does Shuffled-Complex-Evolution-Metropolis algorithm compare to other adaptive samplers (e.g. NUTS)?

I recently heard of the Shuffled-Complex-Evolution-Metropolis algorithm and am curious how it compares to other adaptive MCMC sampling algorithms. Unfortunately I am still learning about optimizing ...
10 views

### How to deal with the different outcomes between pairwise correlation and multiple regression

I have different results from a correlation table and a multiple regression model. I know that it is an effect of multicollinearity because correlations up to $.474$ exist between predictors, but this ...
19 views

### Family-wise error boundary: Does re-using data sets on different studies of independent questions lead to multiple testing problems?

If a team of researchers perform multiple (hypothesis) tests on a given data set, there is a volume of literature asserting that they should use some form of correction for multiple testing ...
9 views

### Hiding the 0 pixel values from the image in display [on hold]

i have a binary image and don't want to show the 0 pixels values in display, so i can superimpose it into an other image how i can do that ? I change the transparency of the image but its for the ...
17 views

### Natural Resource Management: How do I estimate the odds ratio and confidence intervals from model-averaged estimates?

I'm currently working on a model selection analysis in the field of natural resource management. My research question is: what variables are important to an avian species nest site selection. My ...
11 views

### How to interpret the numeric values for “height” using wards clustering method

I am a biology student investigating a new method of creating a dichotomous identification key. I have created a dendrogram using data I have collected from a survey on how people rate how similar ...
12 views

### How to specify a multi-instrument 2SLS [migrated]

I'm looking for a compact way to specify a multi-instrument 2SLS in R. Imagine that there are four treatment categories (A, B, C, and D). There are two waves of measurement, Y_1 and Y_2. A ...
23 views

### Autocorrelated Extreme Events

I'm using a bunch of techniques and methods from Extreme Value Theory to analyze my data. I have a time series representing the number of events happening in a given day. The time series is unequally ...
11 views

### Ranking Data through rank number

Suppose in my survey, through one question, 100 respondents are asked to rank all the 5 product-attribute options for buying a product by giving separate rank numbers (from 1 to 5) to each of 5 ...
19 views

### Predict number of users

I have a pretty basic question, but am pretty far removed from stats and modeling. I have historical data (daily, weekly, monthly, however I want to slice) for a few years and I want to predict the ...
8 views

### The Shepard function in R package MASS

The function Shepard is listed in the help file for MASS::isoMDS, but nothing is said about it. What does this function do?