# Technical Notes


## Within Estimation

A brief technical appendix is available in the PDF file below:

[Sergio Correia - "Least Squares Iteration with Several High-Dimensional Fixed Effects" (2014)](explanation.pdf)

## Why are singleton groups removed?

See [Singletons, Cluster-Robust Standard Errors and Fixed Effects: A Bad Mix](nested_within_cluster.md)
[PDF version available here](nested_within_cluster.pdf)

## Why is there no constant?

(TODO)

## Why is the within adjusted-R2 different from other commands?

(TODO)