# All Questions

0answers
6 views

### Difference between significance and contribution

"What is the difference between "significance" and "contribution" of individual variable to a outcome variable? How to address this while creating a prediction model basically.I understand ...
0answers
5 views

### Matlab GUI background color changing to black when using parallel computing for MLP and SVM

I designed a GUI in Matlab that uses parallel computing in loops for accelerating speed. When I disable parallel computing everything Is normal but when I activate it background color of my GUI and ...
0answers
6 views

### What is $C_{pk}$(test) $-\ C_{pk}$(reference)?

I have a process under test (approximately normal distributed), and I have calculated $C_{pk}$ (a process capability index) for this process. These values are compared to reference values which are of ...
0answers
7 views

### Extremal serial dependence

As part of my analysis of heavy-tailed time series of company returns, I would like to check whether extreme returns exhibit serial dependence, i.e. if extreme events are followed by extreme events. ...
0answers
11 views

### How to calculate sample size?

I need to know how many people of risk group do I have to screen, to get any statistical significance? For example renal cell carcinoma is diagnosed to 25 people from 100 000 population. If they have ...
0answers
9 views

### Interpreting CCF correlation in R

I am using ccf to find a correlation between 2 time series. I am getting a plot that looks like that: Note that I am mainly interested in correlation for the ...
0answers
9 views

### Can a growth model of diseases incorporate vital signs data?

I intend to study the growth rate of diseases among patients of different age groups (cohorts) and comment on the growth of diseases in the next 5 years. Can I incorporate vital sign readings such as ...
0answers
7 views

### Using an odds ratio when data is sparse

Suppose I have around 20 exposures that potentially affect an outcome and I want to see which exposures have bigger impacts on the outcome. So I want to calculate each exposures' odds ratios by ...
0answers
16 views

### what percentage of total variables can be captured in a prediction model

I need to create a model with 45 explanatory variables. As per industry norm, what is the maximum percentage of variables that can be selected for creating a model? Thanks
3answers
17 views

### Can you set a minimum limit for the Y-intercept in R?

I have two sets of test scores I'm using to predict future performance, using multiple regression, and I noticed that the y-intercept is negative. This indicates that for a student who scores a zero ...
1answer
23 views

### How to capture & present lm model output from R

After running iterations of lm() in R, I am now stuck with which components of the model's output to present and how to present them. I know that the r-squared ...
0answers
19 views

### What´s the fastest SVM library for C#

I want trainning my nets faster. I´m using KMLib (not GPU), but the speed is not so good. My problem is a classification one.
0answers
7 views

### Model creation under PLS

I'm developing prediction model based on PLS analysis. I'm looking into variation captured by X(R square X), R square Y, number of components and accuracy after using cross validation, in the process ...
0answers
8 views

### Rule of thumb about how many data points are needed to train a GMM

I have about $10^6$ data vectors, each with 13 dimensions. I'm trying to train a GMM of 256 components using EM algorithm (using GMMBAYES). Is there any rule of thumb about how many data points are ...
0answers
3 views

### Applying Cox proportional hazards model to new data to get absolute risk (Framingham risk score)

I'm trying to apply one of the Framingham cardiovascular event risk scores to a new dataset in order to get absolute risk. D'Agostino 2013 "Cardiovascular Disease Risk Assessment: Insights from ...
0answers
9 views

### Do I need to care about constants in Expectation Propagation

I am trying to approximate a certain factor in my graph. Following Tom Minka's tutorial what I have to do is as follows:  \prod_{i=1}^3 q_{w_i}(\pi_2)\approx \int ...
0answers
21 views

### How to evaluate the fit of a logistic regression

I have a set of data points, which exhibit a solid linear correlation $r\approx 0.9$. I am basically plotting population in certain areas against the number of occurrences of a certain phenomenon (in ...
1answer
13 views

### Graphical Model Equivalent of Matrix Pseudoinverse

The may sound like a strange question but I was wondering if a Pseudoinverse of a matrix could be found using SVD whether there was a graphical modelling equivalent that could be used to estimate the ...
0answers
10 views

### is it possible a nonstationary time series, to produce a stationary ARMA model?

I Have a variable (time series) which is nonstationary. I found that from the graph which seems to have a stochastic trend and the correlogram has a typical nonstationary pattern. After that, I've ...
0answers
10 views

### Only binary predictors — ANOVA, regression, or other?

I am trying to fit a model to predict a quantitative response variable, using several binary variables. In particular, I am interested in measuring the relationship between one of the binary variables ...
1answer
27 views

### Real examples of Correlation confused with Causation

I'm looking for specific, real cases in which a causal relationship was inappropriately inferred from evidence of a correlation. Specifically, I'm interested in examples that meet the following ...
0answers
5 views

### Datasets for market segmentation

What are the gold standard datasets to test market segmentation algorithms with? I'd like to try a few algorithms on known datasets for comparison before I try my own dataset.
0answers
5 views

### Bootstrap confidence bands for time series data

I have time series data for 30 people. The data is knee joint angle versus percent of gait cycle, with data at every 1% of the cycle. I can easily find the mean joint angle at every 1% of the gait ...
0answers
16 views

### How do I investigate how long it takes one variable to affect another in a time series

I am a total newbie when it comes to time series, so it is quite possible this question is duplicated somewhere else, only that I cannot find it because I don't know what this feature is called. My ...
0answers
7 views

### calling weka classifier in matlab with cossValidateModel

how can we call weka classifier in matlab with cross validation? what parameters we can pass to crossvalidatemodel in matlab. weka.classifier.Evaluation.crossvalidatemodel()???
3answers
83 views

### Determination of regression model

I would like to regress total energy expenditure on age, gender, height and weight.But how do I check whether this relationship is linear?
1answer
29 views

### Is there such thing as correlation trees? Clustering rows of X based on correlation between A and B

I have been searching for several days for a method that fits this description, though cannot find one. I'm pretty sure it must exist. The problem (short version): I'd like to run something like a ...
1answer
19 views

### ROC/AUC Confidence Interval

For a single ROC curve (with relevant AUC score), how can you calculate the confidence interval? (The data used to generate this ROC/AUC is available) Given my relatively limited background in this ...
0answers
14 views

### Dynamic pricing optimization of function in R

I'm working my way through a simple dynamic pricing model, and I'm having trouble figuring out how to optimize what I'm working on. I want to maximize $\Sigma_{t=1}^TR(D_t) - h_tI_t$ for the ...
0answers
6 views

### Weighted training in Adaboost

I am learning the Adaboost algorithm, but I am finding difficult on understanding this concepts (I am using the notation of the paper of shapire): What does it means 'Train base learner using ...
2answers
28 views

### Count event using Poisson random variable

An event occurs with a mean of 15 times per hour and a standard deviation of 10 times/h. From the population a sample of 100 individuals is drawn. What is the probability that the sample mean will be ...
1answer
15 views

### Notation: Deterministic Variable, Random Variable, Realization of Random Variable, Function

Is there a standard notation for distinguishing between the following: Random Variables Realizations of Random Variables Deterministic Variables (not random) Functions I am familiar with using ...
0answers
34 views

### I need help about my statistics homework [on hold]

The average number of mosquitoes in a stagnant pond is 60 per square meter with a standard deviation of 16. If 9 square meters are chosen at random for a mosquito count, find the probability that the ...
0answers
21 views

### I need help finding the variance for this problem [on hold]

Find the variance for the values of n and p when the conditions for the binomial distribution are met. n=700 p=.85 a. 89.25 b. 595 c. 9.4 d. 105
1answer
14 views

### Confusion between caret randomForest predict() results and reported model performance

This question seems related, but the consensus was that the issue had to do scaling the data, which I do prior to training, so I don't think that's the issue: Issue on prediction with FinalModel of ...
1answer
18 views

### What is the difference between ex ante and a priori, if any?

In the context of estimating geophysical quantities from remotely sensed data (inverse theory), what do the terms ex ante and ex post mean? For context, see for example this paper by T. von Clarmann ...
1answer
12 views

### R - Test for homogeneity of regression slopes results in singular model

I am trying to check the assumptions of a two-way ANCOVA. So in my model I have two factors (F1, F2) one dummy coded two level covariate (C) one dependent variable (D) In order to check the ...
3answers
472 views

### What is your favorite statistical graph?

This is a favorite of mine This example is in a humorous vein (credit goes to a former professor of mine, Steven Gortmaker), but I am also interested in graphs that you feel beautifully capture and ...
2answers
14 views

### Dimensionality reduction (PCA) for plotting text documents on a graph

I have 50 text documents There are 500 possible words, after a stop list has been applied My term/document sparse matrix is therefore 50x500 I'd like to cluster these documents. One easy way to do ...
0answers
18 views

### 10 fold cross validation model in weka

down vote favorite I am new to Weka. Trying to build a specific Neural Network arcitecture and testing it using 10 fold cross validation of a dataset. Now building the model is a tedious job and ...
0answers
12 views

### Standardizing before/after/at all when using multi-class LDA for pre-processing step

If a multi-class Linear Discriminant Analysis (or I also read Multiple Discriminant Analysis sometimes) is used for dimensionality reduction (or transformation after dimensionality reduction via PCA), ...
0answers
12 views

### Number of Predictors and Classification Algorithm

In general, is it better to include more predictors in algorithms such as SVMs and random forests compared to logistic regression? It seems that when we add more predictors to logistic regression, the ...
0answers
16 views

### How to approximate error on Chi-Squared Fit when bin counts are zero

I am using a galaxy image simulator that provides a 2D histogram that has the number of photons per pixel (bin) $N$. I am currently using a least-squares residual: $\sum_{bin}(f_{data}-f_{model})^2$ ...
0answers
19 views

### 10% dip in February for metrics that count?

February usually has 28 days, unlike it's neighbors January and March which have 31. It seems that most countable things will exhibit, on average, a 10% dip in February for the missing 3 days. This ...
2answers
32 views

### Should I perform multiple t-test or an ANOVA?

My causal comparative study seeks to three questions related to the hypothesis: a) is there a statistically significant difference between the academic achievement of 6th grade mathematics students ...
0answers
9 views

### Meta-analysis in R with multiple probes of a microarray

Regarding a question posted here, I have the same problem and I can't figure out a solution. I started by doing my meta-analysis in PLINK, but I want the confidence intervals of the meta-analysis, ...
2answers
18 views

### Overall Significance vs. Individual Variable Significance in Mutliple Regression

I'm running a statistical analysis for work in which I'm trying to determine which (if any) key economic indicators influence our sales. Here is the summary data that I'm getting when I run a ...
4answers
28 views

### Two groups are significantly different? Test to use

I have two groups of discrete data (integers): ...
1answer
23 views

### Compare coefficients from two separate panel regressions in Stata

I am trying to compare the coefficients of two panel data regressions with the same dependent variable. What I am aiming at is the following: ...
0answers
16 views

### center variable separately for each factor in linear mixed model?

I am working on a relatively simple mixed model where I have two continuous predictors with an interaction term and three sites. I am treating the two predictors as fixed effects and the site as ...

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