# All Questions

0answers
17 views

### Linear Probability Model Construction

I am dealing with a questionnaire consisting of 15 questions. I performed a factor analysis to all the questions and it has given three factors each consisting of 5, 7 and 3 numbers of questions ...
1answer
26 views

### Gibbs Sampler output: how many Markov chains?

When running a Gibbs sampler (for $n=200$ Iterations) with two full conditionals, I get the output $\mathbf{x} = (x_1^{(n)},x_2^{(n)})_{n =1,...,200}$. So $\mathbf{x}$ is the realizations of a Gibbs ...
0answers
18 views

### Undergrad linear regression topic [on hold]

I have to prepare a mulitlinear regression research paper with cross-section data. I thought doing something on the credit ratings of sovereign debt (of one of the Big3 CRAs) or something similar. ...
0answers
38 views

### Dissertation-results section

basically i am testing 2 species of pigs, 2 pigs of the same species in one enclosure and another 2 in a different enclosure, My aim is to see if alterations to feeding regimes have an effect on an ...
0answers
15 views

### maximum likelihood for count data [on hold]

Can maximum likelihood estimation method of parameter estimation be used in categorical data? I was looking for some examples of it. What other parameter estimation techniques work for this kind of ...
0answers
8 views

### optimization - cost function matlab [on hold]

suppose I have a signal x1 always positive of length N = 1000. % signal x1 x=rand(1,1000); x(x<0)=0.01; I have also other 599 signals x2, x3,...,x600 (they ...
0answers
18 views

### How to deal with factors with rare levels in cross-validation?

Suppose in a regression analysis in R, I have a factor type independent variable with 3 levels in my train dataset. But in the test data set that same factor variable has 5 levels. Therefore I can not ...
1answer
48 views

### Rotation in PCA and Factor Analysis

I want to know what elements are (varimax-)rotated when I rotate after PCA and after Factor Analysis. Let’s assume a standardized data vector $X$ of dimension $N \times q$. In PCA, I have the ...
1answer
199 views

### Degeneracy paradox

Say I have a highly biased coin that lands heads with $p_h=0.01$ and tails with $p_t=0.99$, and I flip it $98$ times. The probability of zero heads is ${p_t}^{98} \approx 0.373$. The probability of ...
1answer
43 views

### Statistical models for Obesity data

I have a data on obesity status of women in a country. This data is based on across sectional study. Now I want to find the determinants of obesity among the women. Here dependent variable is binary ...
0answers
120 views

### Compute the probability that the provided classifier label is correct

A binary SVM classifier provides a label $y_c^{(i)}$ for each $i$-th sample provided. This is not assured to be corresponding to its true label $y^{(i)}$, since the classifier could have computed a ...
0answers
17 views

### Difference between Cox Proportional Harzards Model and interval-based logistic model for survival regressions

I have a dataset of timestamped trader transactions (to the second). I want to conduct a survival analysis on the trades where a trade is started at startTime and ...
0answers
40 views

### Maximum likelihood method vs. least squares method

What is the main difference between maximum likelihood estimation (MLE) vs. least squares estimaton (LSE) ? Why can't we use MLE for predicting $y$ values in linear regression and vice versa? Any ...
0answers
21 views

### Is a logit model with a pseudo-R^2 of less than 0.5 a worse model than a coin toss?

I have recently encountered the remark that if a logit model's pseudo $R^2$ is lower than $0.5$ the result is completely worthless because a coin toss is a better model. Is this interpretation ...
0answers
15 views

### Incremental SVD implementation in MATLAB [on hold]

Is there any library/toolbox which has implementation of incremental SVD in MATLAB. I have implemented this paper, it is fast but does not work well. I tried this but in this also error propagates ...
0answers
26 views

### Why does the Journal of Statistical Software use The Persistence of Memory as a logo? [on hold]

I find this to be pretty interesting, does anyone know why this is?
1answer
23 views

### Which is better, replacement by mean and replacement by median?

I'm doing a project that involves replacing missing values in a set of data (first time doing this). This is involves using to methods "replacement by mean" and "replacement by median" to fill in the ...
0answers
16 views

### Clustering not producing even clusters

I'm using k-means clustering to processes running on machines. Dataset sample : machine name, process m1,java m2,tomcat m1,word m3,excel Build a matrix of ...
0answers
13 views

### How to visualise the uncertainty of the classification?

I used SVM to do some classification, and SVM can output some probabilities (likelihood) value measuring how likely each data to be one particular class. For example, Data point 1: 90% (class 1) 5% ...
1answer
17 views

### Data stratification for long-tailed distributions

I'm encountering a few problems successfully stratifying a dataset that is long-tailed to the right. In my research, I came across this excellent response: Sampling from a long tailed distribution ...
0answers
8 views

### Plotting QDA projections in R

When doing discriminant analysis using LDA or PCA it is straightforward to plot the projections of the data points by using the two strongest factors. This can be done in R by using the x component ...
0answers
4 views

### Bootstrap analysis for the estimation of Coefficient of variance of a subset

I wanted to estimate the precision estimated as CV= se/mean of a sampling effort (fishing effort=12 gill-nets) of the mean catches based on fish abundances(CPUEmean). I used in R the function: CV ...
2answers
26 views

### Semi-supervised Learning Training

I have got some data partially labelled. Therefore, I would like to apply semi-supervised learning for this dataset. Basically, I trained the Support Vector Machine (SVM) using the data with labels ...
0answers
4 views

### Semi supervised classification on multivariate data for outlier detection

I have a large multi dimensional unlabelled dataset of cars (price, mileage, horsepower, ...) for which I want to find outliers. I decided to use the sklearn OneClassSVM to build a decision boundary ...
0answers
11 views

### F test in random effects panel regression

I'm using random effects panel regression and I've 3 covariates not statistically significant and I want to test if the three parameters associated with those covariates are jointly equal to 0. Could ...
1answer
17 views

### confidence intervals around lines from glmer in lme4

I have spent a large amount of time trying to figure out how to generate a desired plot, and was wondering if any one can help. The plot is to illustrate an interaction between 'time' and 'group' on a ...
1answer
23 views

### Studying complex systems (complexity)

Complex socio-technical systems is one my research interests. Since I plan to further study such systems and related phenomena, I've done a bit of reading and ran across various books, such as Bar-Yam ...
0answers
6 views

### Graph showing the first stage effect

I am using a 2SLS approach in order to estiamte the effect from increased education. I want to show the effects of the first stage graphically, ie I want to show that the instrument affects schooling ...
0answers
10 views

### How to test for interactions of continuous measure with two repeated-measures factors in R?

I am doing an items analysis of difficulty ratings of a large set of math problems which were constructed to represent the factorial combinations of two binary factors, feature1 and feature2. The ...
0answers
22 views

### Independence of the products of two independent normal variables with a Rademacher variable [on hold]

Let $X$ and $Y$ be two iid $N(0,1)$ random variables, and let $Z$ be a Rademacher variable i.e. $P(Z=1)=P(Z=-1)=0.5$ distributed independently of $X$ and $Y$. Let $U=XZ$ and $V=YZ$. Are $U$ and $V$ ...
1answer
16 views

### Pre-post measurements with a control group

I am running a study looking at the effect of Vitamin C on muscle function. For my study design, I had 2 groups: A treatment (vit C) and a control (no treatment) group. Pre and post measurements were ...
1answer
36 views

### 2SLS probit vs LPM

I am using 2SLS to estimate the effect of education on the probability that one works. In the first stage I regress education on my instrument and the other exogenous control variables. The same ...
0answers
13 views

### Types of regressions

My aim is to see if there is a pattern between demographic features of my participants and the their chance of employability . The 14 human, social and organizational variables are the key factors for ...
0answers
6 views

### Cox MSM or Recurring Event?

I have dataset containing clients' history of active and inactive periods (if there is any) up to present day. Also lots of info as time dependent covariates. I want to model this as MSM, where both ...
0answers
10 views

### 'invalid file specification' when running Monte Carlo simulation [migrated]

I programmed the monte carlo simulation down below. The simulation itself works, but I do not seem able to summarize it. When I run my full program, the do file automatically ends after the monte ...
0answers
20 views

### Multi-Level (Sparse) A/B Testing

I've been reading some articles about Bayesian A/B testing such as: http://engineering.richrelevance.com/bayesian-ab-tests/ but my application requires a framework for handling sparsity and group ...
0answers
12 views

### Using the terms significance, probability or likelihood, in connection with estimators

Imagine a number of variates $x_i$, and a number of processes $P_k$ which depend on these variables, in an unknown way (ie no clear cut formulas to work with). Now consider the scenario where you ...
0answers
10 views

### learning if instances from a dataset are part of the same subset

I was wondering if there are some well-known machine learning methodologies for subset learning. In other words, to learn if two instances are part of the same subset or not (boolean label?). One ...
0answers
13 views

### How would I find out the number of IP addresses that made a google search in Russian from Thailand? [on hold]

Essentially, I want to get an estimate of the number of Russian speakers living in Thailand. There's also the question of how would one filter out the hotels.. but that's probably much more difficult ...
0answers
22 views

### What would be an efficient way of representing a known discrete distribution with a number of samples?

So, say that I have a known discrete probability distribution, for example: [1] [2] [3] [4] [5] 0.08072 0.0642 0.2853 0.3206 0.2492 What I want to ...
0answers
12 views

### Benchmark for price optimization and forecasting

I'm planning to develop a price forecasting and optimization tool...Is there any benchmark for price optimization and price forecasting thanks in advance
0answers
4 views

### weight cases for mean calculations in systematic review

Could you please help? We are writing a systematic review on medicine. We found several studies with different prevalence of skin disease (SD) in samples of different size from different countries. ...
0answers
43 views

### Mean and Standard deviation [on hold]

The filling machine used by a dairy company to fill 1kg containers of yoghurt produces output which follows a normal distribution with mean 1030g (slightly more than 1kg) and standard deviation 20g. ...
0answers
21 views

### Negative binomial mixed effect model for repeated measures with R - prediction and plotting

I have a dataset to analyze in which a response was recorded at the ends of months 1,3,4,5,6 in 187 patients. All patients had the responses recorded in each week, and all patients started a treatment ...
0answers
10 views

### Performing t test, one-way ANOVA from mean and SD using SPSS

I have the following summarized data: Group 1: n=44, mean 12.1, SD 2.0 Group 2: n=56, mean 13.2, SD 2.5 Group 3: n=42, mean 12.7, SD 2.3 Is it possible to perform the t test comparing means of group ...
0answers
16 views

### Interpretation of variance component

In a report, I came across the following table and unfortunately there is no description for it. I have very limited knowledge of statistics. Could someone kindly let me know what the interpretation ...
0answers
16 views

### What is the area under the normal curve that describes the probability that more that 43 households have a gas stove [on hold]

HW 7.4 random variable will be approximated using the normal distribution
1answer
10 views

### Random Coefficient Negative Binomial Model

I have a crash count data and i want to build a random coefficient negative binomial model in R. The dependent variable will be the crash counts and covariates will be Lane width, AADT, shoulder width ...
0answers
10 views

### What does it mean for a function to be “contained in” a confidence band?

So I have this problem that asks me to generate 100 random samples from a standard normal, and I did. It asked me to find a 95% confidence band and I did, using the Python code ...
0answers
9 views

### Jackknife estimator for coefficient of variation

I have one of the estimator of coefficient of variation and i am using jackknife method to reduce bias. I am running R code to do the simulation for this study. The result i am getting is not what i ...

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