# All Questions

13 views

### Stacked Generalization Ensemble Algorithm for regression

I am using stacked generalization(Rupert 1992) for combining multiple(8) heterogeneous base learners for regression. What I understand from the pseudo codes that Train the 8 learners on 8 instances ...
29 views

### Use law of total variance to find unconditional variance of overdispersed Poisson?

First, I need to prove that the distribution of a RV X, where X|lambda ~ Pois(lambda), and lambda ~ gamma(a, B), is a negative binomial. I know that it is, but why negative binomial instead of another ...
10 views

### Ideas for ratio estimation (X and Y from different surveys)?

We are trying to estimate the rate of event X per hour exposed to certain activities (e.g. commuting) by combining statistics from two multi-year cross-sectional surveys, one for the denominator and ...
120 views

### Sliding threshold for hypergeometric test

I have a list of 20,000 genes with an associated p-value (the total number of balls in the urn). I also have a list of specific genes that are "targets" of interest (these are the white balls in the ...
12 views

### Friedman/Wilcoxon test. How to enter data for multiple repetitions?

Id like to run a non parametric test such as the Friedman test on a dependent variable of my 8 subjects who have done a task under four different conditions. I only found examples of how to input the ...
40 views

### Are all sequences of of random (uniform) numbers also uniformly distributed?

If I take some sequences of random numbers generated by a random number generator with uniform distribution, will the resulting sequences be uniformly distributed as well? By example, if I have a ...
24 views

### strucchange problem with csv files [on hold]

Please anyone provide a simple use of .csv file to find breakpoints using R strucchange package. I am new to R and I didn't find any example code which shows how to use strucchange using read.csv() ...
33 views

### Caret package in R - get top Variable of Importance

I am facing two problems while using caret package in R. I am reproducing an example below: ...
16 views

### Data Validation [on hold]

I am doing data validation for customers with specific revenues; I have already received a Target group and a control group with revenue and number of customers; I want to validate the percentage of ...
47 views

### What is name of this distribution and can we have 68–95–99.7 rule for it?

I have a distribution like this: What is name of this distribution? As you know we have 68–95–99.7 rule in ...
13 views

### Descriptive Analysis [on hold]

I have one independent variable pertaining to five questions. I asked these five questions to managers and asked them to give a response on the Likert scale (agree, disagree, etc.). Now I want to ...
18 views

### Instability in glmer model at zero random effect variance

I am getting very different results from glmer (using version 0.999375.37 of lme4) when running in different environments (I can't pinpoint the source of discrepancy, but let's assume some floating ...
8 views

### Add species characteristics, alongside count data, when using ordination

I have count data by site for 15 species, however I also have average size by species by site. I'm looking to use ordination techniques (non-metric multidimensional scaling) to reduce dimensionality ...
57 views

### Test if two binomial distributions are statistically different from each other

I have three groups of data, each with a binomial distribution (i.e. each group has elements that are either success or failure). I do not have a predicted probability of success, but instead can ...
33 views

### Probability of observing a false correlation and confidence limits

In oil and gas exploration/development it is common to use acustic impedance derived from reflection seismic surveys to predict the porosity measured in wells drilled in the reservoir. I often use ...
16 views

### Excel correlate nominal and quantitative

I have the following test data: How do I correlate the "believes" with "before" to determinate if it affects the "after"? When believes is set to 1 the "after" will be (randomly) higher than when ...
87 views

### Can we skip the lower order terms in interactions? [duplicate]

This question is about three-way interaction and the possibility of applying without second lower terms with keeping the main variables in the equation not like the other questions. In fact the other ...
14 views

### Comparing densities of a feature for different classes when the feature is irrelevant to one class

Let us suppose that I have a number of features. I design pdfs for every feature and every class, some of them by smoothing some histogram of training samples, others just by introducing the prior ...
12 views

I wish to run Permanova on categorical data (example CSV structure is below) without any successes. Is Adonis can handle categorical data, an example script will be great. Thanks a lot I have a this ...
7 views

### One-hot encoding before or after split into training and test sets?

Is it safe to do my one-hot encoding of categorical variables before splitting the data into training and test and cross validation sets? I ask because this process alters the dimension of the data, ...
26 views

### How to show whether the average coefficients of determination from one regression technique are better than another across many objects?

I have 50,000 objects on which I have performed two different types of regression. Using cross validation, I obtained the average $R^2$ score from each model on each of the objects. So now I have a ...
40 views

### Omitting a moderator

I'm wondering what the effect is if I don't include moderators in my model? Is this the same or different from an omitted variable bias? I am having a hard time grasping this conceptually. More ...
10 views

### What are the canonical data sets used for testing robust linear fitting?

The UCI database (link) is one of the repositories for canonical data. It has ~295 data sets for use. There are many others. (link) While data can be useful not all data is relevant for all ...
38 views

### How to assess the proportional hazards assumption for a continous variable

I am having a problem with checking the assumptions for a continuous variable in a proportional hazards model. If a variable were a factor with many levels, then I could use the logrank test or check ...
94 views
+100

### Interpreting the random effect in a mixed-effect model

I am looking at several dependant variables for which I created LMMs of the following kind: DV ~ Group + (1|Subject) + (1|Time) Now I am struggling with how to ...
13 views

### adjusting batch effect by multiple linear regression

I am analyzing rna-seq data in the format of counts. There is batch effect revealed by PCA. One method I tried called RUVseq, it estimated the variation basing on control genes, and then added it to ...
14 views

### How to use one variable in regression with many independent variables in lm() [migrated]

I need to reproduce this code using all of these variables. ...
14 views

### Having additional data for only a subset [on hold]

Due to having a maximum amount of data i can request, I can only request additional data for only a targeted group that I am interested in. This data should help my model accuracy for the targeted ...
18 views

### Is there a version of Buhlmann-Straub credibility that uses an non-fixed $\theta_i$?

Everything I've read about Buhlmann-Straub credibility assumes a fixed $\theta_i$ (the unknown parameter that $X_{ij}$, the variable of interest, depends on). Does anyone know of a version where theta ...
22 views

### Optimize number of layers and neurons with an optimization algorithm

I have a neural network that i want optimize number of hidden layers and neurons in every layer using an optimization algorithm like ...
67 views
+100

### Identification of peer/neighborhood effects in a multilevel framework

My question concerns estimation of “peer effects“ or “neighborhood effects” in a multilevel framework. The idea of such an effect is that the behavior of a household (on level-1) is influenced by the ...
20 views

### Factor analysis results

I carried out factor analysis on 31 5 likert-scale questions which represent my 6 constructs. The results showed 6 factors, consistent with my hypothesis but the analysis grouped my questions ...
22 views

### which test should be used to detect the effect of one variable on another?

I have conducted a research on four independent groups of students; one experimental and one control group at two levels. The design of the study was like a pre-test and post-test. I want to detect ...
29 views

### Reproducing simple t-test result with ANOVA

We know that a t-test is just a special case of ANOVA, so I tried to reproduce the result of the following t-test with aov() or ...
18 views

### Imputation model: Pooled model is insignificant. How to interpret?

I have ordinal data on three IVs ranging from 1 to 5 as below: IV1: Not at all Important - Very Important IV2: Not at all Satisfied - Very Satisfied IV3: Performs much Worse - Performs much better ...
24 views

### Point Estimate of normally distributed threshold parameter with unknown mean and variance

I'm new to Bayesian analysis an applied what I learned in John Kruschke's book to simplified versions of a model I previously fitted with non-Bayesian methods. For those simplified versions, even ...
31 views

### Can I normalize Ordinal Data

I have ordinal data on three IVs ranging from 1 to 5 as below: IV1: Not at all Important - Very Important IV2: Not at all Satisfied - Very Satisfied IV3: Performs much Worse - Performs much better ...
20 views

### Composition of bankruptcy probability and firm size

I'm using neural network for a binary classification problem of bankruptcy prediction using patternnet function in MATLAB, so i ...
27 views

### Confidence interval for a regression parameter via prediction

Consider a simple Poisson-regression - GLM - model. There $\exp\left(\beta\right)$s are used as Incidence Rate Ratios (IRR), but their calculation is sometimes not completely straightforward, for ...
15 views

### How to equalize lower accuracy on larger sample sets?

I have a collection of image samples that I want to OCR. I also have the ground truth of the text on these images. Now I OCR them and eg. 10 of 100 samples are wrong. So I got an accuracy of 90%. ...
12 views

### GLMM - time or day/date as a random factor

I have searched for many days trying to find the answer to this question, and am still not 100% sure I am happy with my conclusion. I am interested in looking at the effects of environmental variables ...
28 views

### How to handle variables with low correlation but high loadings in factor analysis

I am doing factor analysis to check the factorial validity of a 14-items scale with four subscales. Two items have low (less than 0.3) correlations with other items in the subscale to which they ...
22 views

### Suggest a statistical method for analysis [on hold]

I have to analyse the data for my dissertation work. Title of my dissertation work is "Estimation of influence of temperature and humidity on milk yield of dairy cattle and its quality parameters". ...
27 views

### How to test for a home bias in a data set?

I'm trying to think how I can test a data set I have, for transactions between buyers and sellers, for a home bias. My hypothesis is that buyers would rather buy from a merchant from their home ...
601 views

### Good form to remove outliers?

I'm working on statistics for software builds. I have data for each build on pass/fail and elapsed time and we generate ~200 of these/week. The success rate is easy to aggregate, I can say that 45% ...
19 views

### Chi square test of association

I wanted to study the distribution of BMI by age. So I randomly made age groups and did a chi square test. Is this appropriate?
10 views

### Should I use ordinal regression to anlyze the likert data? [on hold]

I have got 150 respondents for my survey which is to ask fund managers who manage different types of fund, about thier opinions on some finance theories, with 5-point Likert statements. What tests ...
30 views

### Run Many Small or a Few Big Simulations to Estimate the Mean?

I was just running some simulations on tossing a coin given certain conditions, to test out some ideas I had. I was trying to find the ratio \$\frac{\mathtt{successful\ tosses}}{\mathtt{total\ ...