# All Questions

193,969 questions
Filter by
Sorted by
Tagged with
7 views

### Getting distances from points to their principal curve projections in R princurve? [closed]

I have been using the R package, princurve, to calculate principal curves. Now I want to obtain the squared distances from the points I used to fit the principal curve to their projections in the ...
• 21
10 views

### How can I estimate the variance of the error terms in a conditional/multinomial logit model?

Conditional/multinomial logit models(CML) can be esimated by the Maximum Likelihood Estimation(MLE). The likelihood would consists of choice probabilities: P_{ij}=\frac{e^{V_{ij}}}...
10 views

### Shrinkage / L1 regularization as a loss term versus a constraint (post-process step) with momentum optimizers

I have a complex model with very non-linear operations (divisions, exponentials, matrix inversions, square roots, Cholesky decompositions, etc...) for which I want to optimize the parameters. However, ...
31 views

### Problem formulating a hypothesis test for the mean

Suppose that I would like to support the following hypothesis: h = The average weight of people in New York is 70kg. If I take h to be the null hypothesis then I can only reject it (I assume that ...
• 883
33 views

### Should I join train and validation sets for final NN model training? If yes, when to stop training the final model?

Normally we divide our dataset into 3 sets: train set, validation set, test set. We use train set to find optimal parameters (weights and biases of NN) and validation set to find optimal NN ...
11 views

### How to run a multilevel regression model with crossed random effects: items and participants?

I am trying to run a multilevel regression for my study: I have two random effects; participants (97) and items (which are the 20 words used in the study) Each participant had to spell the same words. ...
1 vote
10 views

### is nrmse scale-dependent?

Im trying to evaluate my regression models using a normalised version of the RMSE, nrmse = rmse(y, y_pred)/rmse(y, y_mean) where y_mean is the array of the same len as y filled with the mean value of ...
• 11
12 views

### How do you get this bifurcation diagram of this 2D discrete time model?

I want to replicate the results of "Chaos in Duopoly Pricing" by T. Puu, which can be found here: https://www.sciencedirect.com/science/article/pii/096007799190045B#section-cited-by. The ...
1 vote
26 views

### Mean-level forecast from rugarch does not match manual calculation

I am looking into the rugarch package and am trying to understand how the one-step-ahead forecast is calculated. Specifically, I am fitting an AR(2)-GARCH(1,1) ...
• 11
33 views

17 views

### is ok to use the same variable in two hierarchies?

I have a dataset with two levels: the city level and person level, at the city level i have the categorical variable "poverty level", in my research estimating the effect of the "...
1 vote
8 views

### Scientific reporting of time-varying covariates at different time frequencies

Say I have the following model: $$y_{it} = \gamma_i + \delta {T}_{it} + \zeta Z_{i(k)} + \epsilon_{it}$$ where $y$ is some outcome for household $i$ in month $t$. $\gamma_i$ denotes household fixed ...
• 5,037
1 vote
17 views

### Balancing Multiple Evaluation Metrics for a Model

When evaluating a machine learning (or other statistical model) against multiple evaluation metrics, is there a standardized way to choose the "best" model? As a concrete example, for a two ...
• 111
32 views

### How to generate a latin square for a user study?

I have to do a user study for a paper to see how using or not using tool X affects the quality of something (defined in my study). The study goes like this: participant 1 uses tool X to do task A and ...
128 views

### Simulating a joint distribution with the inverse method

I have the following joint distribution: $$f(x, y) = 3x^2y^xe^{-x^3}(1 + x),\quad x \gt 0,\ y \in (0,1).$$ I want to simulate a sample of this distribution through the inverse method but I don't know ...
• 65
25 views

### Chi square for three categorical variables

Can I use chi square test with three variables ? The variables are organizational climate (11 dimensions), job satisfaction (7 dimensions) and customer satisfaction (5 dimensions). Likert scale. any ...
15 views

### Best way to approximate head point having only face keypoints

I'm using the BlazeFace model from TensorFlow which only has this few keypoints: I need those keypoints plus a head keypoint, like this one: My question is, which would be the best way to ...
20 views

### Conflicting ACF/PACF after first-difference

I have yearly data. When I do a Dickey-Fuller test it gives me insignificant results, indicating that the series are non-stationary. After differencing them the DFT tells me they are now significant ...
12 views

### How to avoid having very different examples inside a cluster with Kmeans?

Let's say I've created some clusters with Kmeans using 5 features, the Silhouette Score for these cluster are very high, higher than 0.8, and The within-cluster sum of squares is around 130 in this ...
• 45
17 views

### Can we train normalizing flows with Wasserstein distance?

To train flow based models, you usually either use forward or reverse kl as your loss function. My question is, can you use wasserstein distance directly as your loss function to replace kl? I have ...
• 101
8 views

### I think coxph post estimation with big data - confused about the results

I am having trouble understanding if my data is cooked, and how bad, based on post-estimations for coxph. The regression and the cox.zph test is below. Based on the post-estimation, this looks bad ...
• 155
37 views

### Distribution of the Spearman rank correlation coefficient under the assumption of non-zero correlation

There are some papers and some R packages providing exact calculations for the CDF and the inverse-CDF of the (sample) Spearman rank correlation coefficient. My question is: How difficult would it be ...
• 649
1 vote
13 views

### Comparing goodness of fit across parametric and semi-parametric survival models

I've been learning about time-to-event analysis and playing with open datasets + fitting various Cox and parametric models for practice. Other than by visually inspecting the estimated survival curves ...
• 13
13 views

### Which are well-known/popular feature selection methods? [duplicate]

I am trying to test the performance of first reducing the number of features before applying methods such as neural networks for prediction. Due to the fact that the number of observations is not ...
• 141
49 views

### Generate given percentile (or data) from n, mean, median, standard deviation, p1, p25, p50, p75, p99?

I apologize if this should be asked elsewhere. I have the following information: Where N=1808 I am trying to calculate a given percentile (in this case p99.723), or ideally, if possible, generate ...
27 views

### Help with Excel's Regression Output

I'm a junior engineer at a small biotech company and have some (real) data from a fractional factorial DoE (3 factors, 2 levels, 4 test conditions with six replicates each). Currently, we use excel to ...
14 views

### Combining data from multiple studies - best approach?

I'm looking at an old paper on the incidence of HPV infection by age cohorts. The authors present a plot of estimates from many different studies around Europe which looks like this - note the authors ...
• 197
19 views

### Should you clean your data after or before selecting a sample?

Assuming a 500k dataset. For statistical modeling purposes (selecting up to 10% of 500k as a sample). Should I clean the 500k dataset first before selecting a sample or select the sample first and ...
43 views

### football probability

I have the following problem: Suppose that the probability of a football team (T) to win the match with 2-1 is p1 and, given that T scores a goal, the probability that the best player of the team ...
8 views

### Setting up a stacked dataframe for multilevel model analysis in R

I need to set up my data frame into a stacked or long form in order to do a random crossed effects multilevel analysis. My random factors are participants and items (words in the assessment) My fixed ...
5 views

### How to get the Operational items by finer frequency than annual [closed]

I am looking for the availability of some operation items of firms including (Total Assets Turnover- WC08401, Inventory Turnover -WC08136) with a frequency finer than annually from Datastream (...
15 views

### How to conduct t-test for comparing the accuracy of two binary classifiers? [closed]

I am using two binary classifiers that predict the accuracy of samples over a dataset. I need to check if the difference in the mean accuracy between the two models is statistically significant. ...
10 views

### Metropolis and Barker Algorithms: Irreducibility

A question from Brémaud, Markov Chains Gibbs Fields, Monte Carlo Simulation and Queues. Exercise 11.5.2. Metropolis and Barker Algorithms: Irreducibility how do you show explicitly that p_{i,j}= \...
27 views

### Distribution function of the linear combination of standardized student-t quantiles [duplicate]

Assume to observe 2 quantiles, x and y, associated with the z% probability. These quantiles are generated by 2 non-independent standardized student-t distributions X and Y. In case of linear ...
7 views

### Validation Loss for my binary image classifier model is increasing. how to bring it down? [duplicate]

I am new to the domain of Deep learning and I have been trying to create a binary image classifier using a dataset which I created by myself. I am building the model from scratch. It is CNN model. ...
• 1
19 views

### Balancing a dataset in object detection through data augmentation and then random oclusion of classes?

first of all some info about the model I'm using. I'm using YOLOR, which uses a YOLOV5 formatted dataset. I'm trying to detect components off of PCB's which are divided into some groups (visible on ...
21 views
+50

### Choosing response and predictors

Information on the Girth (), Height () and Volume () for 31 cherry trees yielded the following correlations : $r_{12}$ = 0.519, $r_{23}$= 0.598 and $r_{13}$= 0.967. If you were asked to setup a ...
• 83
1 vote