0
votes
0answers
19 views

Polynomial fitting for Shading Correction

I am reading the book Optimization for Computer Vision, and the first example of optimization is a regression for shading correction, in which the author proposes the following polynomial: $p_s(c,x) ...
1
vote
0answers
39 views

Multiple Imputation - Help Needed

These multiple imputation results relate to data I have previously described and shown here - Skewed Distributions for Logistic Regression Three variables I am using have missing data. Their names, ...
0
votes
0answers
15 views

How to calculate standard deviations/z-score given a confidence level

So, I'm a total statistics neophyte, and need to calculate the number of standard deviations/z-score based on a confidence level, in javascript. I have a table which provides some data: ...
1
vote
0answers
20 views

R random forest on Amazon ec2 Error: cannot allocate vector of size 5.4 Gb [migrated]

I'm training random forest models in R using randomForest() with 1000 trees and data.frames with about 20 predictors and 600K rows. On my laptop everything works fine but when I move to amazon ec2 to ...
0
votes
0answers
15 views

Scaling data constrained to be varying between a floor and ceiling set of values

I have data that range continuously between the values of 0 and 2, usually somewhere in between close to 1 on average. 0 is a "floor" and 2 is a "ceiling." The data describe more than one group of ...
0
votes
1answer
22 views

Minimum sample size for 1 way ANOVA?

I have tested a group of participants over various time points and I want to investigate whether mean score on each subsequent time point is significantly different to the mean score at baseline (eg. ...
0
votes
0answers
34 views

Find the radius of a cluster, given that its center is the average of the centers of two other clusters

I do not know if it is possible to find it, but I am using Kmeans clustering, and I am stuck to the following. In my implementation, I create with two different threads the following clusters: ...
0
votes
0answers
24 views

Kruskal–Wallis non-parametric alternatives for groups with different shaped distributions

My question does't duplicate this question, even if the titles are nearly similar. The Kruskal–Wallis test "assume that the observations in each group come from populations with the same shape of ...
0
votes
1answer
15 views

How many hypotheses are needed when researching one category with multiple likert-scale question

I am currently researching two groups on their willingness with 5 questions on a 7-point Likert-scale. My hypotheses are: $H_0$: There is no difference in willingness between the two groups. $H_1$: ...
0
votes
0answers
12 views

Clusters as input for classification

I'm currently performing clustering as a batch job and then in real time I'm assigning new points to cluster whose centroid is closest to new arrived point. The other approach that I see is to ...
0
votes
0answers
21 views

Modeling continuous abundance data with a GLM in R: how to select the correct distribution family?

I have abundance data (counts) that I have standardized by area sampled, making them continuous. I would like to explain them with my two independent variables using a GLM but I am having trouble ...
5
votes
2answers
141 views

Skewed Distributions for Logistic Regression

I have been developing a logistic regression model based on retrospective data from a national trauma database of head injury in the UK. The key outcome is 30 day mortality (denoted as ...
1
vote
2answers
21 views

What means “CDF of one group does not cross the CDF of the other” from the dunn.test description? [duplicate]

From the dunn.test manual: "CDF of one group does not cross the CDF of the other". What this means? I am not a statistician, but I want to understand. What I found ...
3
votes
1answer
73 views

Does the birth date of professional boxers matter? Prove/disprove what an astrologer might predict

As a followup to my question about the birth month of boxers, I am posing the fundamental question along with my hypothesis (testing if there is any truth to a conclusion an astrologer might make): ...
4
votes
1answer
41 views

Has the free kick spray in soccer an effect? Binomial Testing

In Germany a referee supported the use of the free kick spray introduced on the World Cup 2014. He reported some statistics. His data supported the assumption using the spray leads to more goals after ...
0
votes
0answers
21 views

How do you conduct regression analysis using SPSS when there is more than one dependent variable? [migrated]

How do you conduct a regression analysis in SPSS using 1 predictor variable (personality score) and 8 dependent variables (stigma scores to 8 different case studies)? I have tried to use this process ...
0
votes
0answers
7 views

Why will higher order of polynomials using poly() function solve in lme model and lower orders won't?

I am modeling repeated blood pressure data over 24-h (300 patients, 13,000 observations) and have fit the following model with 9th order polynomial which has solved: ...
1
vote
0answers
20 views

Zero-intercept poisson regression model predicts better than a model with an intercept?

I have read some blogs/articles saying that intercept should not be suppressed. Recently, I used glmm.admb to model a ZIP (Zero-inflated Poisson) model which is giving better results without an ...
0
votes
0answers
20 views

Regression without intercept [duplicate]

I saw that here explain how to get the formula for getting a regression without intercept but I already know it (for example in R you get it outomatic with ...
1
vote
0answers
25 views

The econometrics of a Bayesian approach to event study methodology

Event studies are widespread in economics and finance to determine the effect of an event on a stock price, but they are almost always based on frequentist reasoning. An OLS regression -- over a ...
0
votes
0answers
12 views

How to find rows of a given matrix that satisfy a certain property? [migrated]

Suppose that I have a 90x4 matrix, say matrixgroup1, and some of rows are zero vectors. I want to find the rows that are not zero vectors. The code that I try was: ...
1
vote
1answer
14 views

Is this problem convex ? (regularization term on xTw)

Suppose we want to solve the following: $$ \min_{w} f(x^Tw, y) + \lambda g(x^Tw) $$ with $f$ a (logistic) loss and $g$ something like a variance. Is this a convex optimization problem ? What are ...
0
votes
0answers
25 views

How to check that the selected features are not overfitting

I'm trying to select best features for sentiment classification for a set of reviews, and using penalized SVM and Logistic regression to perform such task. by basically iterating over different ...
1
vote
1answer
119 views

Curious distribution

While checking my Android App Rating I saw this It's almost a quadratic progression! Is there any explanation for such a rating?
3
votes
1answer
42 views

Is stratified meta-analysis more or less objective than meta-regression?

Reviewer asked me why I use meta-regression as a way how to deal with heterogeneity among effect sizes instead of conducting stratified meta-analysis. I tried to google "stratified meta-analysis" and ...
1
vote
0answers
19 views

Maximum Entropy classifier, high precision but low recall

I'm working on a sentiment analysis study of twitter data using the Maximum Entropy classifier. I've gathered dozens of thousands of tweets. To produce features, I used unigram, bigram and dictionary. ...
1
vote
1answer
47 views

Hourly predictions using time series

I'd like to build a model based on time series. I have a dataset with records every 30 minutes for three months. What is the difference between modeling these data with the following kinds of ...
0
votes
1answer
22 views

Finding maximum likelihood estimates of parameters of multiple normal populations

I've just started studying maximum likelihood and likelihood ratio tests. I've calculated the maximum likelihood of a normal population with unknown mean and variance. However, I've been given this ...
2
votes
1answer
27 views

A reference for Pearson's chi-squared testing

I am wondering if there is a reference for the Pearson's chi-squared test suitable for technically-sophisticated audience that simply presents when the test (in its various forms) is appropriate and ...
0
votes
0answers
9 views

Add data series to highlight cases on a box plot (Excel, SPSS or R) [migrated]

first time user of this forum - guidance on how to provide enough information is very appreciated. I am trying to replicate the presentation of data used in the Medical education field. This will help ...
0
votes
0answers
12 views

Application of Inclusion-Exclusion Principle for circular arrangements

N people are invited to a dinner party and they are sitting on a round table. Each person is sitting on a chair there are exactly N chairs. So each person has exactly two neighboring chairs, one on ...
0
votes
1answer
30 views

What is maxout in neural network?

Anyone can explain what does maxout layer do in neural network? How to perform it? What does it different to normal activation function? I try to read the 2013 "Maxout Network" paper by Goodfellow et ...
2
votes
0answers
19 views

Empirical confidence bands

Suppose I would like to evaluate how well, the following kernel density estimator $$\hat f (x) = \frac{1}{nh}\sum_{i=1}^nK\left(\frac{x-X_i}{h}\right)$$ works. I simulate data 1000 times and obtain ...
0
votes
0answers
7 views

How to add a fixed variance structure do a GAM

I am using GAM to fit a smooth line to represent the recovery of timber stocks following forest harvest. The data is heterogenous and I do not want to transform it. I understand that a nice way to ...
0
votes
0answers
12 views

Confidence interval of a function of Maximum Likelihood estimates

I have a probability density distribution for a variable $x$. This distribution is a function of another variable $Y$, that is $P(X=x \space |\space Y)$. I observe one $x$ value in nature (the ...
0
votes
0answers
5 views

How would you get the standardized coefficients in errors-in-variables (EIV) regression?

I had some occasions to use the EIV regression in Stata, (and R, with the program built by Culpepper & Aguinis, 2011, "Using analysis of covariance (ANCOVA) with fallible covariates"), but I ...
2
votes
1answer
19 views

Confusion about confusion matrix, or why 'power of test' + $\beta$ = 1?

Consider a confusion table summarizing the outcomes of $n$ tests of hypothesis $H_0$ for $n$ independent experiments: ...
5
votes
2answers
119 views

Statistical significance of birth month of professional boxers

I looked at the birth dates of the top 100 ranked professional boxers of all time (67 of them to be exact). 40% of them were born during certain 3 month-long time periods. If birth date of boxers ...
5
votes
1answer
38 views

What is the best visualization for Cramér's V?

When visualizing a linear correlation between two continuous variables, one uses a scatter plot, usually in combination with the Pearson product-moment correlation coefficient. When doing the same for ...
3
votes
1answer
28 views

Best clustering algorithm for real estate data

I want to cluster real estate data to determine average price patterns in city and rural regions. My data set contains size, number of dorms, bathrooms and coordinates of the properties. Which would ...
2
votes
1answer
15 views

Normality requirements across tests

I would like to understand the reason why normality is required in many tests. T-tests: I read that what needs to be normal is the sampling distribution rather than the sample distribution. But since ...
0
votes
1answer
16 views

Combining multiple p-values

Is there any statistically relevant way to combine multiple p-values measuring different hypotheses but that are all trying to measure the same thing "in spirit"? Eg, if I wanted to measure some ...
0
votes
0answers
8 views

How to analyse categories ranked 1 to 5 between two groups

I currently have 5 categories. I asked two groups to rank activities from 1 to 5: 1 is the most preferred activity and 5 the least preferred activity. How could I analyse this to see if there is a ...
0
votes
0answers
13 views

cumulative uncertainty with time series predictive model

So I have a time-series with a set of variables a, b, c... and another measured variable y. What I do is using the initial state of a,b,c and y (at t0), I predict what y "should" be at the next time ...
3
votes
3answers
157 views

Why Normalizing Factor is Required in Bayes Theorem?

Bayes theorem goes $$ P(\textrm{model}|\textrm{data}) = \frac{P(\textrm{model}) \times P(\textrm{data}|\textrm{model})}{P(\textrm{data})} $$ This is all fine. But, I've read somewhere: ...
1
vote
0answers
24 views

Two-proportion z test: is it best for my problem, and can I pool data from multiple “replicate” populations?

I am examining populations (cultures) of yeast cells and scoring them for a particular trait. The data is categorical; within a population, a yeast cell either has the trait or it does not. I wish ...
0
votes
0answers
10 views

Combining different metrics to calculate composite score

Let's assume I have 3 metrics to evaluate a student. 1)Test Marks (0-50) 2)Weight of the student (KGs) 3)% Attendance (0%-100%) I want to calculate a total composite score which is a function of ...
0
votes
0answers
4 views

fixed-effect nested factors in R with only SOME combinations present

I have a large data wth numerical response and two categorical factors: date and site. There are about 350 dates and 25 sites, but not all sites have observations on every single date (most have only ...
0
votes
0answers
11 views

Confused about cross validation for model stacking

I'm reading section 8.8 of Elements of Statistical Learning, and though I keep reading the section on calculating the ensemble weights I'm missing something. It says that the stacking weights are ...
0
votes
0answers
21 views

Model failed to converge

I'm doing a variable selection for the interaction gender:type2 now ...

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