Implement various machine learning methods from scratch

1. Causal Inference

propensity score matching for causal analysis from scratch using Python

2. Decision Tree

decision tree and random forest from scratch using Python

3. IRT (Item response theory)

implementation of IRT model with stan

4. Variational Bayesian Learning

a. Latent Dirichlet Allocation

variational bayesian LDA from scratch with Go

b. Matrix Decomposition

variational bayesian matrix decomposition with Python