---
title: "Reid Ji (@reidstonji) | Hashnode"
description: "Building is cheap now. Knowing what to build isn't. Data picks, AI builds, every result goes public — misses included."
url: "https://hashnode.com/@reidstonji"
---

@reidstonji

# Reid Ji

@reidstonji · Hangzhou, China · Joined September 2026

Building is cheap now. Knowing what to build isn't. Data picks, AI builds, every result goes public — misses included.

[Website](https://numberandreason.com/)

## Comments

[Right — in-sample is the honest caveat. The finding is the drop itself: a raw signal looks great until you control for need size. So it's a hypothesis to test out-of-sample next — and I'll publish whichever way it goes.](https://hashnode.com/posts/no-method-has-been-shown-to-predict-what-software-to-build-so-i-m-backtesting-mine-on-three-years-of-store-data/6ac83de63ea584ea9edc7f40/comment/6ad2fed9874abf8e984c785b#reply-6ad333fbbbe835398831fb2d)

Reply · Article · Oct 17 · [No method has been shown to predict what software to build. So I'm backtesting mine on three years of store data](https://hashnode.com/posts/no-method-has-been-shown-to-predict-what-software-to-build-so-i-m-backtesting-mine-on-three-years-of-store-data/6ac83de63ea584ea9edc7f40)