---
date: "2025-11-10T00:00:00Z"
categories:
  - linkedin
  - visualisation
description: "I used data analysis to uncover why old movies rank so high on IMDb. It’s selection bias: obscure classics are rated by enthusiasts, while popular modern hits suffer a 'democracy penalty' from casual viewers who give lower scores."
keywords: [imdb, selection bias, data analysis, movie ratings, statistics, claude code]
---

I always wondered why **old movies are rated so high** on IMDb.

For example, 12 Angry Men (1954) with just ~900K votes ranks about as high as Inception (2010) with ~2M votes. Few people I know have seen 12 Angry Men. So where does this high rating come from?

My theories were:

- Old movies really _are_ that good.
- IMDb's algorithm is biased towards old movies.
- People remember older movies fondly.

Actually, it's none of these. **It**'**s selection bias**.

Few people watch a 1950s black & white drama: cinephiles, film students, etc. They love it and give it 9s and 10s.

Everyone watched Inception. The casual majority thinks it's fine, not life changing. Maybe a 7 or 8.

This creates a paradox: **obscurity protects ratings** while **popularity is its own punishment**. Only "devotees" watch obscure movies - leading to better ratings than widely seen movies.

PS: This data analysis and story were authored by Claude Code. That includes the statistical significance validation.

Story: https://sanand0.github.io/datastories/imdb-democracy-penalty/index.html
Prompt: http://github.com/sanand0/datastories/tree/main/imdb-democracy-penalty
Code: https://github.com/sanand0/imdbscrape/pull/1

![](https://files.s-anand.net/images/2025-11-10-why-old-movies-are-rated-so-high-linkedin.jpg)

[LinkedIn](https://www.linkedin.com/posts/sanand0_i-always-wondered-why-%F0%9D%97%BC%F0%9D%97%B9%F0%9D%97%B1-%F0%9D%97%BA%F0%9D%97%BC%F0%9D%98%83%F0%9D%97%B6%F0%9D%97%B2%F0%9D%98%80-activity-7395757328177774592-zJlE)