All Questions

3 views

hard statistics question

A sample of size n=19 is selected from a population with mean 50. After a treatment is administered to the individuals in the sample, the mean is found to be M = 55 and the variance 64. Are the data ...
6 views

how to interpret metrics for my model

I understand how these metrics are determined but can anyone give me typical poor, acceptable, good, and outstanding values RAE and RSE?
7 views

Test cases for HMM implementation

I've written some simple code to fit Hidden Markov Models with discrete emission probabilities (similar to this implementation, which follows Rabiner's tutorial very closely). I'd like to extend my ...
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How to do one-vs-one classification for logistic regression?

I have a dataset with 4 clases and I want to apply logistic regression with one-vs-one classification. So, first I train for each pair of classes a logistic regression classifier (i.e. calculate the ...
6 views

Given the same before-after differences within groups, is it relevant whether time trajectories converge or diverge?

Both drugs are associated with the same decreases in mean blood pressure in both scenarios. Given that we attach the same meaning to any blood pressure decrease of the same amount, does scenario B ...
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In my experiment, I diluted a chemical in water and recorded its Raman spectra. Then I repeated this with different concentrations. As I can clearly see some peaks decreasing in intensity when I ...
20 views

Time dependence and cumulative logit regression question

I'm looking to do some research with the GSS (the General Social Survey; a survey that asks over a 1000 people every year various questions and collects their demographic information as well). I'd ...
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Using lmer for repeated-measures and RCBD

I am trying to figure out the best way to model the error using lmer for a randomized complete block design (RDBC) where we measured soil nitrogen weekly for 2 years. There are: 4 Blocks (A, B, C, D) ...
16 views

I have been trying to fit Adaboost to work with continuous valued data set and the more I read the more I keep getting confused. I have read about the multiclass Adaboost with log(K-1) addition to ...
9 views

How to train lstm layer of deep-network

I'm using a lstm and feed-forward network to classify text. I convert the text into one-hot vectors and feed each into the lstm so I can summarise it as a single representation. Then I feed it to the ...
36 views

I would like to know exactly WHY NN inputs have to be within -1 and 1

My questions is similar to this other question but I want to know exactly why the inputs have (or is strongly recommended) to be within this range. I know computers can deal with numbers within a ...
39 views

How do I interpret and report the output of a logistic regression in R on data that are all binary (0,1)?

My minimum adequate model is shown below. My independent variables (e.g. One, Five) represent habitat categories for which species have either been designated to (i.e. the assessment found that they ...
9 views

Finding Cointegrating Vectors

If I have N time series of I(1), is there a procedure to find which tuples are conintegrated without running regressions for all subsets of N and checking the residuals? Is Johansen procedure used to ...
8 views

Distances between successive points - Statistical Test

I have a set of experimental data which comprises distances between successive points: I also have a set of similar data that has been generated by a model that attempts to recapture the ...
14 views

Basic Parking Probability question

how would you solve the following problem ? Parking spaces at a business school are arranged by a random monthly lottery. there are 3 spaces for every 10 students who want one and all of them have an ...
7 views

Why does GEE produce the same parameter estimates as OLS?

The quasi-likelihood function optimized under GEE is: $S_k(\beta)=\sum_{i=1}^{K}\frac{\partial\mu_i}{\partial\beta_k}\nu_i^{-1}(y_i-\mu_i)=0,$ where $\mu_i=h(\textbf{x}_i,\beta)$ is the conditional ...
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R - Variation of “How to plot decision boundary of a k-nearest neighbor classifier”

This is a question related to How to plot decision boundary of a k-nearest neighbor classifier from Elements of Statistical Learning? I've been playing with that example, and would like to try to ...
9 views

What is the best way to learn hadoop [on hold]

I would like to learn hadoop. I know a bit of linux and sql. What would be the best way, handson training or online videos or anything else. My assumption is since I don't have the hardware required, ...
7 views

How to train a svm classifier with a linear and rbf kernel? [on hold]

I have a image database of size 2000 , each of which is converted into feature vector of size 1024. Similarly there is another test dataset of size 2000 for testing purpose. I would like to see the ...
12 views

How can you detect outliers in a group of face images?

I'm trying to filter an image database which contains some irrelevant pictures. All the faces are labeled with points around the face contour, eyes, mouth, eyebrows, have age and gender. The faces are ...
21 views

Sample size calculation, linear regression

I have just had my viva and my sample size calculation was criticised as it was based on r2. I was told to base the sample size on the minimal magnitude of association. My outcome variable is HbA1c, a ...
27 views

Getting Expected Value from Monte Carlo Simulation

There are two independent uniform continuous random variables $X$ and $Y$ (such that $0 \leq X \leq 10$, $0 \leq Y \leq 10$). The function $f$ is the difference between the two random variables ...
17 views

Statistics in Agronomy [on hold]

I'm looking for good references, textbooks or survey papers on the application of statistical methods in agronomy, farming or food industry. Anything related to these domains in terms of modeling, ...
4 views

Training and Activating a 2 layer deep network

I've been working with synaptic.js to make neural-networks in the browser for a while and I've decided I want to implemented deep-learning for a project I'm working on ( connecting an lstm to a ...
11 views

2SLS causal effect interpretation

I would be very grateful if someone could help me to interpret 2SLS results produces in R. In particular, I am interested in the result on causal effect. I want to know whether it is CC that affects ...
9 views

Regression imputation of missing data based on OLS effects

Let's say we have a two-way with interaction experiment with missing data. Being the dataset: ...
2 views

Resouces, tutorials or courses for data/text manipulation [on hold]

Online and free course or complete tutorial for data/text manipulation?
8 views

multivariate general linear model

If I want to test if losing control over eating during pregnancy (my independent variable) can predict birth weight (dependent variable) and to do that I did general linear regression. Now if I want ...
8 views

what exactly is projected gradient descent?

I am reading the article with title "metric learning by collapsing classes" http://papers.nips.cc/paper/2947-metric-learning-by-collapsing-classes.pdf.There are some questions which has bothered me ...
4 views

Choosing a tech stack for data/text manipulation [on hold]

What is the most powerfull technonology stack for huge data/text manipulation, python, R or Bash tools (sed, awk, cut, tr, etc). What are the pros and the cons of which one?
12 views

time series forecast problem

i have a resaerch in forecasting population size in my country by using exponential smoothing method, my data was for six years, for several states, i used spss program and used time series analysis, ...
16 views

Interpretation of coefficients in linear regression: first difference of logs

what is the correct interpretation of coefficients in time series regression when using first differencing on logs of the DV and in certain IVs. FD(lnY)=c+beta1*ln(X)+beta2*FD(lnZ) The log ...
4 views

What is the mathematics behind the GAM prediction intervals?

From the R gam function available in the gam and mgcv package there is the option to obtain ...
58 views

Why does drawing one card at a time increase the probability of choosing the Ace of Spades?

If you draw 5 cards from a standard deck of 52 cards, then the probability of your hand having the Ace of Spades is: $$\frac{51\choose 4}{52\choose 5} = \frac{51!5!47!}{4!47!52!} = \frac{5}{52}$$ If, ...
78 views

Is nominal, ordinal, & binary for quantitative data, qualitative data, or both?

I'm getting wrapped around data types and I need some help: If you look at the picture above (taken from here), it has the data types like this: Quantitative (Discrete, Continuous) Qualitative ...
18 views

How to do an analysis of variance?

I ran an experiment in which probands had to rate (1 = dislike, 2 = like) how much they liked each of five fruits (apple, peach, orange, banana, strawberry). I now have results: ...
26 views

Strictly Stationary Time Series with Infinite Moments

Can someone give me an example of a strictly stationary time series with infinite moments? I am reading a book on Time Series by Wayne A. Fuller where it is said that a strictly stationary time series ...
11 views

Clustering Standardized Mortality Ratio

I am bit new to the whole clustering idea. I have a data set that gives information about the SMR in the different states of America from 1995-2000. Hence I want to apply clustering techniques ...
10 views

Fixed effects regression using sex as the unit of analysis

I have time series data for 10 time points for both males and females. Would it make sense to have sex as the entity in the panel approach?
26 views

Non parametric analysis

The my dataset is not normal distributed. In order to apply a non parametric analysis, exist only the Kruskal Wallis test or others? I need to find a test similar to ANOVA to apply a dataset not ...
29 views

What is the best way to test normality for a very large sample size 15000? [duplicate]

Also do I need to test the normality for the categorical data? Thanks
14 views

Gaussian processes - Covariance matrix is not positive definite with SE kernel [on hold]

I am trying to implement the simplest example of a Gaussian process in Matlab. I want to draw samples from a prior distribution. Also I want to use the Squared Exponential kernel. Unfortunately the ...
11 views

Non-vector data and SVM?

My research is on antimicrobial peptide classification and prediction. I have gathered peptide sequences of lengths ranging from 10 - 200 and classified them using different machine learning ...
8 views

Distribution of trace of the covariance matrix

I try to implement a two stage procedure for a multidimensional confidence region with a fixed shape regarding to the handbook of sequential analysis (Ghosh 1991, p. 33ff). To do that, I have one ...
7 views

Recommended Study Area For Processes

I am looking for a machine learning area that deals in processes for logistics. If anyone can show me some use cases or even point me in the direction of a couple of algorthims. Im currently using R ...
33 views

Observed Vs Unobserved Variables [duplicate]

Can anyone explain the difference between observed variables and unobserved variables (preferably in plain English ) ?
7 views

GP regression - Matern kernel gradient issue

I'm trying to use a Matern 5/2 kernel for GP regression, so my kernel function is $K(x,x')\triangleq\theta_0(1+\sqrt{5r(x,x')}+5/3r)\exp(-\sqrt{5r}),$ where \$r(x,x')\triangleq\sum_{d=1}^D ...
21 views

Complement of statistical significance test

I am applying statistical significance tests like the Kruskal-Wallis, Wilcoxon and ...