# All Questions

0answers
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### Shortcomings of logistic regression

I've recently started exploring logistic regression for modeling purposes and well... it's just performing pretty poorly. Apologies for a very broad question, but I just can't figure out why! Here's ...
0answers
4 views

### What is the distribution of the random variablle

An aircraft passenger is tested to check if he is infected by H1N1 virus.
0answers
4 views

### (binary) Matrix completion with less known data

Recently, I meet such problems, I call it matrix completion problem. For example, the row denotes the users and the column denotes items. And If one user like the ...
0answers
3 views

### Simulation of CI of amount of values in different intervals by adding noise to original data

I am having a hard time trying to solve this problem, so maybe some of you guys can sort it out. I have a large data set containing a value describing the thermal comfort in buildings called PMV. The ...
0answers
7 views

### How do I report the data from a Cox proportional hazard regression model on SPSS

I was just wondering if there is a set way to write the results within a CPH model, I have obtained results from SPSS and I have values for Sig B and the 95% Confidence interval. What I am after is ...
0answers
5 views

### Variable selection that splits factor levels

This question is related to previous ones but I believe distinct. I am primarily interested in prediction and I have access to LASSO variable selection (but without factor level grouping) using the ...
0answers
6 views

### Ggplot gives “arguments imply differing number of rows” error in geom_point while it isn't true - how to debug? [migrated]

I have two objects of type Large SpatialPointsDataFrame named st2 and st10. They come from the same source. They both plot without problems with: plot(st2) or ...
0answers
8 views

### Question on SPSS Mantel_Haenzsel output

SPSS provides these three statistics as output for the crosstabs command STATISTICS=CMH(1): Tests of Homogeneity of the Odds Ratio Tests of Conditional Independence Mantel-Haenszel Common Odds Ratio ...
0answers
7 views

### How do I install and use Shogun toolbox in matlab? [on hold]

I want to use Shogun toolbox in matlab (windows) but their installation guide is not clear. Does anyone know simple steps to install shogun toolbox in matlab?
0answers
14 views

### Strange behaviour of list in R [migrated]

I ran on a very strange behaviour. I am trying to evaluate a rather long list (Generated code). ...
0answers
5 views

### Linear model for RCBD

Hi i am told to write a linear model for my stats assignment under an RCBD. ...
0answers
6 views

### The Shogun Machine Learning toolbox for SVM with precomputed kernel and zero bias

Can I use the Shogun Machine Learning toolbox for SVM with precomputed kernel and zero bias. I should be able to input pre-computed kernel and I also should be able to set bias zero.
0answers
3 views

### mean queue delay ( nonpreemtive priority)

I'm trying to solve a problem where all arriving items (arrival exponential $\lambda = 1/5$) are divided into into groups, those who are served within 5 units of time and those who have their service ...
0answers
12 views

### Discrete Choice Models

for mulitnomial (or mixed) logit models, when the choice set is too large, either strategic sampling or random sampling of the choice set can be used. My question would be: Is that also true in ...
0answers
12 views

### Distribution of random sample of confidens intervals containing the true mean

Given 50 random samples, each of size 25, from a normal distribution with mean 20 and standard deviation 5. From the 50 samples, you can find a 90% confidens interval for the mean. Let Y be a random ...
1answer
16 views

### Can quadratic constraints be handled by Bayesian methods?

I want to solve a regression method whose parameters are under quadratic constraint a'*a=1. Is there any method in Bayesian statistics to handle this constraint? Thank you in advance.
0answers
6 views

### You will randomly select 10 balls from the box with replacement what is E(bar X) [on hold]

A box contains 100 numbered balls - 21 with the number 1, 36 with the number 2 and 43 with the number 3. You will randomly select 10 balls from the box with replacement and you take the mean of the ...
0answers
5 views

### How to adjust data to remove influence of one or more features

For my first real data science project I would like to develop a model which better reflects review quality than than "useful" votes. I am working with Yelp's latest Academic data set but this ...
0answers
4 views

### Method to estimate times of individual impulses from composite response

I have a detector that registers a sequence of "hits" over a period of time. Each hit produces a signal that has the approximate form ...
0answers
21 views

### Best way to determine normality of data

I believe there are many ways to determine if data is normal or not: histogram shape QQ plot skewness kurtosis shapiro test. Which of the above is the best way to determine if data is normal and ...
0answers
5 views

### Correspondence analysis reconstitution formula

I have a question about the reconstitution formula for the correspondence analysis. Let X be the observation matrix with variables by columns and observations by rows. I look for a decomposition  ...
0answers
9 views

### Sampling For Correlation

Suppose we have population P that is split into large number of close size sub-populations (e.g. country is split to zips). For each sub-population a small sample was drawn and average of a variable X ...
0answers
4 views

### Passing a function with parameters as an argument to another function in R [migrated]

Consider an example: I want to pass a function with or without parameters to another function and use it in the following way: ...
0answers
11 views

### Multicollinearity, feature selection for discriminant analysis and the error rate

I have a question regarding feature selection in LDA/QDA and deciding to eliminate variables to find an optimal model (lowest misclassification rate) I'm looking at how quadratic and linear ...
0answers
12 views

### The Binomial Distribution

I am trying to understand why when asked for the probability at least 1 success does it take the form 1-P(X=0) or 1-BINOM.DIST(0,1,.18,1). I am trying to understand this logic. Can you explain in such ...
0answers
16 views

### Why sandwich estimators aren't always used in OLS regression?

I asked before what is the intuition behind sandwich estimators. I must still missing something because I don't understand why sandwich estimators are not always applied to OLS residuals. Can you ...
0answers
6 views

### Is it possible to calculate the covariance btwn data and a subset of the data?

I have a regular and complete time-series vector and have created a subset of this vector based on a particular sampling algorithm (say every 10th value). To calculate the error variance of this ...
2answers
16 views

### Probability selection of elements from a set

If we have a set $S= \{s_1,s_2,..,s_n\}$ and each element in the set $S$ has an assigned probability $P_n$. Then a selection process is applied to the set $S$ such that, each element $S_n \in$ $S$ is ...
0answers
4 views

### error for xreg and newxreg matrix size in an arima model

I am using auto.arima to forecast a daily data and used holiday and weekday dummies as regressors. I am getting an error which does not make sense. When I want to predict a 7 step ahead forecast, it ...
0answers
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### Team level analysis: how to aggregate control variables such as tenure, gender and working status?

I'm currently conducting research on a team level analysis (59 teams) in which i estimate the effect of voice climate -> team voice behavior, team voice behavior -> team learning behavior, and, team ...
0answers
27 views

### Did I meet my goal? [on hold]

Based on below did I meet the goal of < 10 minutes H0 = Median 15 Ha=Median less than 15 results Count (N) =207 Count for test= 188 Median= 10 Wilcoxon Statisic =2517.50 p value (1-sides)=0.000
2answers
18 views

### paired-sample t-test

I have taken weight measurements before and after a treatment. When I run a paired sample t-test and if there is a significant change, would it be possible to make the claim "95% of the time ...
0answers
20 views

### Can I say there would be only 2 groups with such features in this data and prove it using cluster analysis?

I assume that there would be two groups that will emerge within the data with my assumed features. I run cluster analysis and best number of cluster (elbow, dendrogram, etc.) shows it will be 2 and ...
0answers
11 views

### Do assumptions for estimators affect population parameters?

TL;DR: Specifying a model (a collection of restrictions over a sample space) specifies the model parameters. Specifying an estimation procedure adds additional number of restrictions (assumptions?). ...
0answers
25 views

### Why only full ARIMA models in auto.arima?

It seems that the auto.arima() function in the forecast package in R only considers full ...
0answers
8 views

### How to get the improvement index in monthly basis for employees absence

I have the following information for each month of the year: Total Absence Days in a given month Total Headcount in a given month I want to get an index in which I can compare months and see if ...
4answers
218 views

### How to sample when you don't know the distribution

I'm fairly new to statistics (a handful of beginner-level Uni courses) and was wondering about sampling from unknown distributions. Specifically, if you have no idea about the underlying distribution, ...
0answers
18 views

### Cannot intuitively grasp “Standard normal deviate”

I cannot intuitively grasp the meaning of "Standard normal deviates". I think It would help if you provided me with either/all of the following: (i) real life examples of their application, (ii) an ...
1answer
31 views

### Tobit versus OLS

There is a dependent variable which is measured in £ and can take the form of £0-£100,000. It is effectively the value of the payment made. If it takes the form of £0 it means a payment was not made ...
1answer
27 views

### Expected lifetime of a device with two parts each having spares?

Consider a device with two parts : (1) and (2). Part (1) has 2 spares and part (2) has one spare. Lifetime of part (1) and its spares have iid exponential distribution with rate lambda. Lifetime of ...
0answers
12 views

### Estimating a probability distribution with a discrete and continuous part

This is a question more for advice and a suggested starting point than anything else (though anything else is cool as well ) The data that I have is something like this - 1,000,000 data points of ...
1answer
12 views

### Significant autocorrelation in time series decomposition random component

I'm very new to time series analysis. The data below represents about 8 years of aggregate daily visitors to some tourist attractions. I'm trying to examine the random component of some time series ...
0answers
6 views

### Correlation of latent variables: Sum-scores vs. SEM correlation

I use a set of about 20 attitudinal items. My aim is to investigate if these items represent a number of dimensions and to what extent these dimensions are correlated. Exploratory factor analysis ...
0answers
15 views

### Text mining conferences [on hold]

What are the most significant text mining conferences? Please include one conference per answer. Please also include URL link for the conference.
0answers
16 views

### Some doubts about using time random effect

I'm starting with lme4 and GLMM. Maybe this question can be basic for experimented researchers, but I'm still learning. I have a pooled data where every ...
0answers
15 views

### Error “initial value in 'vmmin' is not finite” when changing factors in ordinal logistic regression

I've generated some fake data to give a simple example of ordinal logistic regression. My data set (raw data here) looks like this: ...
0answers
9 views

### test to be applied

I have applied 3 treatments at 10 different concentrations of each on a bacteria to see if they affect its existence. my response variable is binary i.e. 1 for effective and 0 for ineffective. basic ...
0answers
12 views

### Statistical arbitrage using eigen portfolios [migrated]

I was trying to understand below paper https://www.math.nyu.edu/faculty/avellane/AvellanedaLeeStatArb071108.pdf Page 20 explains about "Entering a trade". I wan't to know clearly what it means to ...
0answers
8 views

### Repeated measures - sum of biomassproduction

I am student in biology. For my examination I conducted a greenhouse experiment with gras. Actually I am not sure how to develop the correct model and unfortunately I haven't found an answer in the ...
0answers
12 views

### Impute missing data of a variable

I'm currently working on spatial spillovers in agriculture at the municpal level with cross-section data. But, I do have missing values for the investment in capital at the municipalities though the ...

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