# All Questions

135,194 questions
1answer
13 views

### Help examining predicted probabilities from nested logistic models

I am having trouble explaining a recent finding to myself. I'm not sure if I'm asking a redundant question, but here is my situation: 1) Suppose I want to model the estimated probability of some ...
1answer
25 views

### Using GDP to predict Probability of Default [on hold]

I would appreciate if you could help me to answer on how to use the GDP (Gross Domestic Product) to predict the probability of default (Probability of corporate defaulting in their payment). By using ...
0answers
10 views

1answer
16 views

### Types of Normality Test used in Minitab

I recently performed a normality test for a set of data. I noticed that when I use the AD test, the p-value is < 0.05; whereas when I use RJ test, the p-value showed is >0.05. My question here is: ...
1answer
33 views

### Determine if data is IID

I have data usage from Android and Iphones, and I want to check if the Iphone users consume more than the Android ones. I thought about doing a t-test, but I am not sure if the ID - I think we should ...
0answers
5 views

### How to reduce false positives when novel negative images are visually similar to training images?

I am noticing that my ResNet model is showing some false positives in cases where novel negative example images are somewhat visually similar to positive examples. In these cases, it's not simply ...
0answers
10 views

### How do I determine the critical r value for Pearson correlation if I compute the result via bootstrapping?

The critical r value for a Pearson correlation analysis depends on sample size. For example, consider a test with the following parameters: n = 20 alpha = .05 I ...
0answers
38 views

### How to run linear regression with constraints in R? [duplicate]

If I have the following data n<-1000 x1<-rnorm(n,1,1) x2<-rnorm(n,2,2) x3<-rnorm(n,3,3) e<-rnorm(n) y<-3+0.5*x1+0.2*x2+0.3*x3+e I want to fit a ...
1answer
23 views

### How would heteroskedasticity look like with negative correlation?

I hope I formulated the question correctly, but I am purely interested in heteroskedasticity: cov($e_i$,$e_j$) and not in autocorrelation with the dependent variables. So positive correlation of the ...
0answers
9 views

### Checking equality of covariance matrices using Box's M test in multifactor MANOVA

With only one factor (independent variable) in multivariate analysis of variance (MANOVA), Box's M test can be used to check the equality of covariance matrices. ...
0answers
9 views

### How to evaluate the goodness of a KNN-based recommender system?

I'm building a content-based recommender system and I'm using KNN. That means, for each test instance I'm using KNN to find the most similar objects, and then come up with a recommendation. However I'...
0answers
18 views

### Running a Multilevel Linear (Mixed-Effects) Meta-Analysis Model without a variance-covariance matrix

I have a dataset that I want to run a meta-analysis on. However, the data has a hierarchical structure with several endpoints per study and where studies are further clustered together. So, I should ...
0answers
9 views

### Spatio-tempral Bayesian Poisson model convergence investigation

I am fitting a spatio-temporal Bayesian Poisson model with 22 explanatory variables, an offset variable, 2200 observations and non-informative priors. I am using the package ...
1answer
68 views

### Why do two implementations of the Anderson-Darling test produce such different p-values?

I want to check the normality assumption of my series I am trying to figure out the way is computed the p-value of the Anderson Darling in R packages, goftest and <...
0answers
38 views

### How to interpret eigenvectors in PCA analysis?

I'm trying to apply the output from PCA analysis I've run on some yield curve history and am getting a bit confused. I have followed the steps below, From a history of the yield curve ($m \times n$ ...
1answer
24 views

### Rho Spearman correlation test interpretation for sample equal to population

I have done a pair of cuestionaries to measure a pair of variables in a small population, 87 people, so I have taken the whole population as a sample, the cuestionaries have likert scales as answers (...
4answers
38 views

### Question regarding independence of events

I am reading Wasserman's book and his class notes. In the notes, I found the following statement If A, B are disjoint, both having positive probability, then A and B cannot be independent. Now, if ...
0answers
17 views

### Stepwise logistic regression: What exactly is meant by eliminating features based on contribution?

I would like to know how my program is selecting and removing features during stepwise regression. I'm using R's caret package which in turn I think is using stepAIC from the MASS package. I was ...
1answer
32 views

### Bayesian Inference - determining probability of win [on hold]

We're running an experiment on our landing pages, showing different variants to users. We want to know which variant (page) performs best. We need 100,000 users for our experiment. That's going to ...
1answer
73 views

### 7 accidents per 30 days on average, but variance is 12. Why Poisson distribution can't be used here?

Let's say a city has 7 accidents per 30 days on average. We can use Poisson distribution formula where $\lambda = 7$ $$\frac 1 {n!} (\lambda t)^n e^{-\lambda t}$$ But in Poisson distribution the ...
0answers
26 views

### at what probability will the probability we start considering the data?

For example I have this problem, Do Americans tend to vote for the taller of the two candidates in a presidential election? In 30 presidential elections since 1856, 18 of the winners were taller than ...
2answers
22 views

### No error in the training/validation dataset

Suppose I have a linearly separable dataset, divide into training and validation sets. Will a perceptron learned on the training dataset be guaranteed to have no error on the training dataset and on ...
0answers
12 views

### How to infer the bounds on the R-squared value given the relationship between individual features?

Let say you have three variables X1, X2, and Y, all normally distributed, zero mean, unit variance. When you build a simple linear regression using: ...
0answers
10 views

### hypothesis testing to check for occurrence

I am struggling to understand if I can make such a hypothesis or not and if so, which test is best to validate it. I have a data with a size of 50 (quality of wine) I see that a sensory quality ...
0answers
13 views

### How to construct envelope graphics for residuals? [on hold]

Using R we can plot the envelope graphic for regression residuals using the function qqPlot. My question is: How to construct ...
0answers
11 views

### aregImpute or mice for imputation of survival data

I would like to use multiple imputation to analyse associations between an exposure variable (exp) and different disease risks in a dataset with some missing data (...
0answers
21 views

### Independent variables and moderator variables correlate (three-way interaction)

let's assume I hypothesize: H1: A direct effect of X1 on Y H2: A direct effect of X2 on Y H3: A two-way interaction between X1 and X2 H4: A three-way interaction between X1, X2 and X3 H5: A three-...
1answer
18 views

### Competing Risks Likelihood in each State

I have a competing risks model where every observation starts in state 0 and ends up in either state 1 or state 2. I have the following cumulative hazard functions for each transition to state 1 and ...
0answers
11 views

### Bayesian Model Validation in BEST

I am trying to perform BEST using pymc3 for finding difference between 2 groups of values (values from same group before and after). After performing similar analysis as shown in the link, I see no ...
0answers
5 views

### How to use seasonal features in time series regression with models such as xgboost?

I have a hard time understanding how one can create seasonal indices such as a yearly mean or (x - yearly mean(x)) and use them as predictors for monthly n horizon forecast. For example: I want to ...
1answer
20 views

### How to use derivatives of a function to better estimate its variance over the domain?

How to use derivatives of a function to better estimate its variance over the domain? I have a scalar smooth function $f(x)$ and a multivariate random variable $x$ with known distribution (e.g. ...
0answers
5 views

### Attribute Sampling Math question for inventories

I hope this is the right forum for this, but I'm terrible at stats and got tasked to help a QA team do some math. I'm trying to figure out how to do the calculations to be able to say something to the ...
1answer
23 views

### Anomaly detection with complex seasonality

I am working on a anomaly detection for a batches of daily time series (non-hierarchical) that exhibit both yearly and weekly seasonality. I tested a few algorithms and it appears that tbats() from ...
0answers
17 views

### Visual representation of strong associations of two categorical variables

I have a dataset of one categoric variable "supermarket" for each individual person and multiple "product" categories per person and supermarket. E.g.: Person 1 went shopping in supermarket X and ...
1answer
18 views

### Effect Modification, Confounding, and Correlation

I am trying to estimate the effect of a policy intervention (X) on patient outcome(Y) from an administrative data. In the data set, around 20% of the patients have received the intervention. Even ...
0answers
10 views

### permutation test and calculate the robustness of p value

I have two datasets , I am making it as simple as I can so that people can help me. I have two data, one is that I see in a database that a number of 3 is repeated 10 times in a certain regions. so I ...
1answer
17 views

### Stan: output some (but not all) intermediate variables of interest [on hold]

I am a newcomer to Stan but quite a Stan enthusiast by now. Currently I am working on a Stan application involving a somewhat complex computation with a bunch of intermediate variables of which I ...
0answers
13 views

### Keras LSTM for timeseries forecasting help with error messages [on hold]

I am trying to understand how to use keras for supply chain forecasting and i keep getting errors that i can't find help for elsewhere. I've tried to do similar tutorials; sunspot forecasting ...
0answers
18 views

### R - nlm and Weibull Maximum Likelihood

Good day, I am working on an assignment where I have to Calculate the maximum likelihood estimates of $\alpha$ and $\lambda$ along with their standard erorrs on the basis of an independent and ...
0answers
9 views

### Assess collinearity in conditional logistic regression [on hold]

I have a cross-over design dataset (each patient has two observations - one for case interval; the other one for control interval). All the interval-level variables (exposure and other covariates) are ...
1answer
21 views

### Which statistical test should be used for several samples frequency distributions?

I have the frequency distribution of muscle fiber size from several control and several problem animals and I'd like to compare both groups, but all the statistical tests I know for frequency ...
0answers
13 views

### How are cumulants of order higher than one independent of average? [on hold]

I have background in physics. How are cumulants of order higher than one independent of average?
1answer
18 views

### How to determine earliest point of change in repeated cross sectional study?

I have an experiment where animals are exposed to a temperature change and then a continuous response variable is measured at set time points after the change. I have a baseline, 8 hours after change, ...
0answers
15 views

### gereration of random in R [on hold]

I want to generate a random number in R using my specific generator ...
2answers
36 views

### How can one interpret a heat map plot

I am doing a stats assignment in python and during my preliminary data analysis I created a heatmap plot and would like to be able to explain the correlation among the variables. However, I don't ...

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