# All Questions

216,404 questions
Filter by
Sorted by
Tagged with
37 views

### Sampling line segments within a box

I'm at a bit of a loss for where to start with a sampling problem I'm having so any and all direction would be helpful. I essentially want to sample line segments of identical length within a bounding ...
• 31
6 views

### Computing Expectations in Fisher Information Matrix for Gaussian Mixture Models

Consider a Gaussian Mixture Model (GMM) with $K$ components: $p(x) = \sum_{k=1}^K \pi_k \mathcal{N}(x; \mu_k, \Sigma_k)$ where $\pi_k$ are mixing coefficients, $\mu_k$ are mean vectors, and $\Sigma_k$ ...
• 133
91 views

### Low $R^2$ puzzle

I conducted an experiment and using the data I fitted a basic linear regression model. The top chart displays the fit. The $R^2$ is abysmally low indicating almost no explanatory power (adjusted $R^2$ ...
• 4,675
2k views

### In roulette, is the frequency of getting long sequences of reds lower than that of shorter sequences?

In a roulette game that continues indefinitely, is it correct to say that achieving a sequence of 100 consecutive reds will occur far less frequently (perhaps once in every million spins) compared to ...
• 73
20 views

### What's the point of the left Fcrit value in a 2-tailed F-test?

In a 2-tailed F-test, there are 2 critical values right? One on the right and one on the left. You can get the one on the right by using an F-table and the one on the left by getting the reciprocal of ...
1 vote
29 views

### Generate Quasi Random Numbers for a Multivariate DIstribution

Algorithms like Sobol or Holton provide quasi random numbers (that is, the numbers "look" random in the sense of a uniform distribution, but they are deterministic) in the hypercube $[0,1]^d$...
• 138
233 views

### When trying to find the quartiles for discrete data, do we round to the nearest whole number?

I have 2 cases: First, I want to find the first quartile to the set data: 1,2,3,4,5. Normally we calculate the qaurtile as: Now $Q_1 = \frac{2+1}{2} = 1.5$. But they never state if its continuous (i.e....
• 131
1 vote
18 views

### Lower Tail Bound for Noncentral chi-squared distribution

A noncentral chi-squared random variable $Z$ is of the form $$Z = \sum_{i=1}^k X_i^2$$ where $(X_1, X_2, \ldots, X_i, \ldots, X_k)$ be $k$ are independent, normally distributed with mean $\mu_i$ and ...
• 11
11 views

### How to compute mutual information between a scalar random variable and a vector random variable? [duplicate]

I have a vector random variable $X = (x_1, x_2... x_n)$ where each $x_i$ has a discrete value. I also have a discrete scalar random variable $Y = y$. Is mutual information between the two defined? If ...
10 views

### How to formulate this entity resolution problem?

Problem formulation Given: Two sets of elements: S = {s₁, s₂, ..., sₙ} and T = {t₁, t₂, ..., tₘ} (you can think of them as two sets of records) Each element e ∈ S ∪ T has properties: A real number v(...
30 views

### A/B Test Proportions when one of the samples has zero responses

Hi everybody I made an experiment about the conversion of customers that had some responses in group A but 0 responses on group B. If I input these values in a two-sample proportions_ztest It gives me ...
20 views

### Should I use ROC curve in my training set after training a Random Forest classification model with k-fold cross validation?

I have a conceptual question: after dividing a dataset into a training and test set (70:30), both are balanced and shuffled, should I use the Confusion Matrix and the ROC curve of a model generated by ...
74 views

### Derivation of expectation with subscript

I am going through the derivation for Denoising Diffusion Probabilistic Models (DDPMs) based on Calvin Luo's Diffusion tutorial, where he finally develops the reconstruction term, the prior matching ...
24 views

### A Method for Functional Misspecification

I have been thinking about unbiasedness recently. An idea for came to my mind . Imagine that the dataset is separated into three different parts as training, the data that will be added to training ...
18 views

### Suitable function of BLUPs in lme4 package [closed]

I want to analyze a data set includes 12 genotypes across 2 conditions or environment(drought stress and normal) in 4 years. I used the analysis of an article that used the BLUPs method as my analysis ...
7 views

### training convergence stagnation in image reconstruction using Vgg19 [closed]

--------------------------------------Context--------------------------- I am trying to implement this paper Universal Style Transfer via Feature Transforms. In the paper they trained 5 decoders for ...
5 views

### Why is parallel bootstrapping in R slower than sequential bootstrapping (using boot and future packages)? [migrated]

I'm conducting a bootstrap analysis using the boot package in R with the option parallel = 'snow' (for Windows computer). However, computing in parallel is slower ...
1 vote
29 views

1 vote
13 views

### Title: Issues with Fitting a Quasi-Periodic Function with a Trend Term in Python

I'm trying to fit a quasi-periodic function with a trend term to my time series data using Python. The data consists of monthly observations from 1963 to 1976. My goal is to model the data with a ...
• 369
23 views

### as.POSIXct results in NAs for some of my data

I want to convert my date column into Reproducible dataset: ...
42 views

### Drawing uniformly from a skewed distribution

Are there methods to draw samples from a skewed population in such a way that the samples are uniformly distributed? For example, if I want to show a correlation between height and salary, but the ...
• 83
88 views

### Difference between anova () and summary ()? [closed]

Original post summary: I want to run a two-way repeated measures ANOVA. What is the difference between the following functions: anova(), ...
1 vote
22 views

### Model still overfits after hyperparameter tuning, dataset balancing and convolution layering

I am trying to classify either an image of 25x25 px stacked together as 50x25 px is the same(1) or different(0). I am using keras to create the NN layers. There are 10,000 instances of both 1s and 0s ...
• 111
34 views

### If you had a disease with a 50% chance of living 5 years and a 30% chance of living 10 years, at 5 years what odds now of getting to 10 yr [closed]

See title for all info needed. Please also provide the method/ maths.
• 1
38 views

29 views

### Simple but important question: how do you write down the formula for the probability density of data in general? [duplicate]

In machine learning many data can be thought of as generated from a probability density function (also called probability distribution). But most probability textbook only discuss probability density ...
26 views

### How to derive points for each variable in nomogram by hand?

I'm dealing with nomograms at this time, but I don't really understand how to derive the exact points for each variable by hand (or in a mathematically way). To be concrete, I brought a simple example:...