# All Questions

0answers
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### One Class SVM Training in LIBSVM

Could you kindly reply my queries in context of using LIBSVM for One class SVM. Assuming I have samples from one class only, do I need to put a lable for each sample...but a training file without ...
0answers
3 views

### have two ID with four dimensions and a mediator with two factors and a DV with four dimensions. [on hold]

want to calculate the direct and indirect effects between them. and what kind of techniques should used to analyze data from questionnaire. thanks
2answers
59 views

### Analysis for checking if an Ensemble model is a better fit for a dataset than Primitive model

I have a dataset and have the option to apply either GLM (primitive) or a Random Forest (ensemble). So far the Random Forest is giving way better results than the GLM. As it is generally believed that ...
0answers
20 views

### Sufficient data volume for inference

This question was probably discussed before but I failed to find it here. Let's say I have a medical data which contain some biomarker measurements for cases (patients with disease) and controls ...
0answers
12 views

### Optimizing selection from varying sets

On pages of website(s) I have a set of potential messages to choose from and only one or two slots to show them in. (think 'this product is on sale' or 'this product is new'). On each page the set ...
0answers
19 views

### What does “shift invariant” mean in convolutional neural network?

I saw a term describing the feature detectors, i.e. shift invariant. What is that mean? Paper: 1989 Generalization and Network Design Strategies
0answers
39 views

### Relationship between water quality at different sites and characteristics of study areas

I'm investigating the relationship between the mean values of water quality parameters and the characteristics (e.g. soil types (%), landuses (%), rainfall (mm), rock types (%)) of the study area ...
2answers
240 views

### Was this the appropriate regression model?

I was recently proof-reading a friend's thesis (for their writing, not stats usage) when I came across a usage of a regression model which I would regard as incorrect. However, I'm pretty new to the ...
0answers
5 views

### Computational complexity gaussian continuos hidden markov model

As I know, the continuos Hidden Markov model does not use the emission probability matrix $B$ but obtains the probabilities of being of a given state by a gaussian (univariate or multivariate) pdf ...
1answer
42 views

### Asymptotic distribution of a recursive statistic

I have a (time series related) test statistic which is asymptotically normal. I would like to know what is the asymptotic distribution of its maximal value obtained by a recursive estimation. For ...
0answers
21 views

### Should a BoxCox transformation to normalize the skewness of data be applied to all the predictors?

If there are few predictors that are highly skewed among a larger set of predictors in case of a linear regression problem, should a BoxCox transformation be applied to only these few predictors or ...
0answers
50 views

### Combining micro data for an econometrics paper

I am researching data for an econometrics research paper that I am doing but I am completely stuck. I am not looking for help doing the actual research, just guidance if my statistical method will be ...
1answer
31 views

### “weight” input in glm and lm functions in R

I am confused with the definition of the weights in glm and lm. Using the McCullagh and Nelder (1989)'s notation, If random variable $y_i$ is from the Generalized Linear Model (GLM), then its density ...
1answer
5 views

### Using Difference in Difference (DiD) to measure the impact of austerity measures?

I am trying to see if there is any causal relationship between the rise in vote share of France's leading extreme right-wing party Le Front National and the rate at which austerity measures took place ...
1answer
53 views

### Biostatistics and Pure [on hold]

I hope this is not "opinion" question but I am curious as to whether or not the study of statistics and probability theory in the realm of cancer genomics is considered "less philosophical" than the ...
0answers
14 views

### Experiment report with hypothesis for simulated model

I'm setting up an experiment for a simulation. I'm not sure how to formulate the hypothesis. The model used in the simulation is the first iteration, so I'm just using 2 attributes, 1 independent (A) ...
2answers
45 views

### What is the purpose of Leads and Lags in a time series?

I will analyse stock prices and i don't understand the purpose of leading and lagging. can you please suggest me some preliminary analysis on the stock prices also, this will help me for my thesis.. ...
0answers
6 views

### Proc Mixed for a random slopes model - contrast the slopes?

I have a need to make predictions about a set of students $^1$ who are nested under teachers, under schools, under districts. I have produced the below model, and I now wish to do some forecasting at ...
0answers
9 views

### Neural Network JavaScript Form Field Validation

I want to build a neural network and ultimately end up with functions that can validate various types of data in a web form using JavaScript. This way I can create new data types by telling the ...
0answers
13 views

### within-MZ twin model using sem in Stata

I'm working with some twin data and would like to estimate something exactly akin to xtreg using sem in Stata. The structure of the data is pretty generic: there's a family id, there's a within family ...
1answer
23 views

### How to compare repetitive data by using SAS? [on hold]

I have a question about how to code this change line data, in fact , i want to set up a dummy variable 'change line' = 1 or 0 by comparing different yes persons in different row , for example by ...
1answer
17 views

### How do search engines generate related searches?

I would like to know how search engines like Bing generate related searches when the user starts typing into the search box. From what I gather, there has to be some sort of a ranking algorithm where ...
1answer
29 views

### Convert categorical percentage data into an overall mean

I have survey data in which the answer choices were "categorical" (0, <15%, 15-30%, 30-45%, 45-60%, 60-75%, 75-90%, >90%). In retrospect, this should have been a free response question, but I'm ...
0answers
12 views

### Partial derivative from lme or lm object

I'm looking for an R package, or another approachable way in R to obtain the first partial derivative of choice from an lm or lme object. I'm aware of http://stats.stackexchange.com/a/8253/13758 but ...
1answer
25 views

### How to bound a probability with Chernoff's inequality?

In my class, we were given Chernoff's inequality as $$P(X\le -t) \le e^{(-(\lambda*t - \log( E(e^{-\lambda*x}))))}$$ $$P(X\ge -t) \le e^{(-(\lambda*t - \log( E(e^{\lambda*x}))))}$$ It says that to ...
0answers
8 views

### initial status X time interaction

I am modeling change in a continuous variable over time using linear mixed modeling in SPSS. I would like to examine the possibility that initial status (i.e., pretest performance on the DV) interacts ...
1answer
16 views

### How can I show that my sample is random and a good representation of the population?

Okay, I'm looking at a population of user reviews. I have collected a random sample of the reviews and studied the trends of the words used and sentence structure. How do I make inferences about ...
0answers
5 views

### Comparing structure of disconnected networks of different sizes

I am trying to figure out a way to evaluate and compare the structure of multiple (600+) disconnected networks of different sizes (from 31 to 5000 nodes). From what I have read in the literature, ...
1answer
67 views

### Why is the sampling distribution of variance a chi-squared distribution?

The statement The sampling distribution of the sample variance is a chi-squared distribution with degree of freedom equals to $n-1$, where $n$ is the sample size (given that the random variable of ...
1answer
35 views

### How to interpret ANOVA output when comparing two nested mixed-effect models?

I've got two models (all variable are count variables): ...
0answers
9 views

### How do I determine sample size to validate a requirement when I have a lot of margin?

I apologize if a similar question has been asked, but my search has yielded no results. I am having some trouble nailing down the correct methodology to use to design an experiment I am working on. ...
0answers
51 views

### Multinomial logistic regression does not match actual data

I was wondering if someone with experience running multinomial logistic regression could look at my data file and results, and explain why the results turned out the way it did. The background: I've ...
1answer
16 views

### Which Machine Learning algorithm: Sorted list of tags given metadata?

Our system allows an admin to manage a database of university courses. These courses have multiple fields, like the department, a title, and a description. I am adding the ability to add learning ...
1answer
71 views

### Unintuitive interpretation of probabilities when doing logistic regression

The observations in my dataset can be split in two classes. The observations in class 1 are for sure correctly labeled. The observations that has been designated to class 2 have a huge percentage of ...
1answer
35 views

### Statistical test of stock returns product

Say I have a sequence of stock returns: $X_1, ..., X_n$. Then I make a sample of products: $X_1X_2, X_2X_3, ..., X_iX_{i+1},..., X_{n-1}X_n$ How to test, if the sample mean is significantly different ...
0answers
24 views

### In a longitudinal analysis, is it valid to adjust for a covariate as change-score and also include the baseline covariate value?

We have a situation where we want to test the association between X and Y, but the change in X from baseline is more interpretable. There are several possibilities I see for setting up the model. But ...
0answers
6 views

### Borgatti Key Player Problem (KPP) in Python

Has anyone come across any Python implementation of Borgatti's proposed Key Player Problem (KPP) algorithms? I'm interested in solutions using NetworkX and particularly interested in implementations ...
0answers
15 views

### Some questions about AlgDesign for Fractional Factorial Design in R

I have a few Design of Experiment type questions about the AlgDesign package in R that I can't find answered online: Will using the center=TRUE option in the ...
0answers
27 views

### Ratio of Odds Ratios?

How would one compute the ratio of odds ratios for unlinked (but theoretically overlapping samples)? I basically have one dataset that can be considered my "population" or "universe" of data, and ...
0answers
32 views

### Stolen base success vs Independent catcher and average catcher

I would like to know if my thinking on this is correct. Note: This is not a homework or work question, I am just interested in learning about comparing averages and how it applies to the problem set ...
0answers
5 views

### LibSVM totalSV for multiclass

I am performing classification of K=9 classes using linear SVM with libSVM (MATLAB warp) I am using 400 samples of data to perform the training and I'm getting: totalSV: 203 I know libSVM uses ...
0answers
18 views

### sample size to estimate variance

I am trying to follow a thread Calculating required sample size, precision of variance estimate? and am facing difficulty understanding a step in the answer, specifically the step given below \$ (n-1) ...
0answers
24 views

### Determining Appropriate Test: two categorical groups with a goal (split test?) (Newb)

I've spent several hours online researching an appropriate means of using statistics to determine whether or not variation test results are meaningful, or just chance. If the testing took the format ...
0answers
8 views

### Calculate variance of subpopulation given variance of overall population and its complement

I'd like to be able to calculate the sample variance for a subpopulation [B] given the sample mean and variance for its complement [A] and the overall population [A+B]. I have the sample mean and ...
0answers
24 views

### clustering analysis of large amount of time series

I would like to cluster a set of time series, which are composed of around 50000 different time series. Are there established algorithms/package that can handle this scalability problem?
0answers
17 views

### Performing a comparison between a sample distribution and population distribution in excel or nvivo

What is a relatively easy stats test to perform in excel/nvivo that is arguably reliable and valid and a good method for comparing a sample's normal distribution with a population's normal ...
0answers
4 views

### Function approximation, inverting and finding input values subsets based on output value

Suppose I have a set of input/output values for some unknown and complex function which I want to approximate using some machine learning algorithm. The input variables are integers or reals. The ...
0answers
18 views

### MAR Vs. MNAR: attribute's missingness determined by the value of another attribute

Suppose I have a training data set that predicts the whether a person is unemployed or not using a decision tree. I have a certain set of attributes that I use to predict this. But for all samples ...
1answer
12 views

### Correcting multiple marginals in a subsample of a survey

My question in short: How to assign weights to a subsample of a survey in order to fit multiple features simultaneously to their original marginals? ...and now the details: I have some data set X of ...
2answers
36 views

### Managing 'prefer not to says' in sensitive questionnaires

Consider a questionnaire where we ask someone about their sexuality. The five options, for simplicity, are: Heterosexual Homosexual Bisexual Other 'Prefer not to say' Assume we ask the population. ...

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