---
title: "General vs one-class CF"
subject: "Information System"
chapter: 7
key: "semester_8/information_system:general-vs-one-class-cf"
source: https://www.bctengineer.com/q/semester_8/information_system/general-vs-one-class-cf
site: BCT Engineering
---

# General vs one-class CF

Information System · Chapter 7: Web based information system and navigation

- Asked in: 2073 Magh, 4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/information_system/general-vs-one-class-cf
- Whole chapter: https://www.bctengineer.com/md/semester_8/information_system/chapter-7

## Question

Compare general collaborative filtering Vs One-class Collaborative filtering.

## Short answer

General collaborative filtering uses explicit multi-level ratings with known negatives, focusing on rating error. One-class collaborative filtering uses only positive implicit feedback, treating missing data as ambiguous, and evaluates with ranking measures like precision at k.

## Answer

**General collaborative filtering** uses explicit, graded feedback such as ratings from 1 to 5. **One-class collaborative filtering (OCCF)** works where only positive implicit feedback (clicks, purchases, likes) is observed.

| Basis | General CF | One-class CF |
|---|---|---|
| **Feedback type** | Explicit ratings (many classes) | Implicit, only positive (1) |
| **Negative examples** | Known (low ratings) | Not available |
| **Missing entries** | Not rated; ignored | Mixture of dislike and unknown; must be handled |
| **Preference strength** | Known from rating value | Estimated from frequency or count of actions |
| **Data example** | Movie ratings 1 to 5 | Product purchases, page views |
| **Data volume** | Users must make effort to rate, so sparse | Easy to collect, more plentiful but noisy |
| **Methods** | Neighbourhood, matrix factorization on observed ratings | Weighted matrix factorization, negative sampling, ranking methods |
| **Evaluation** | Rating error (RMSE, MAE) | Ranking measures (precision@k, recall, AUC) |
| **Example** | Netflix star ratings | Amazon purchase history |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What feedback does general CF use?
   A. Only implicit positives
   B. Explicit ratings with many classes
   C. Only negative signals
   D. Server logs
   Answer: B. One-class CF uses implicit positive feedback. (Key point: Feedback)

2. In general CF, what does a missing entry mean?
   A. Not rated, and it is ignored
   B. A dislike
   C. A purchase
   D. An error
   Answer: A. In OCCF, missing entries are a mix of dislike and unknown. (Key point: Missing entries)

3. Which evaluation measures suit one-class CF?
   A. RMSE and MAE
   B. Page load time
   C. Disk speed
   D. Ranking measures such as precision@k, recall and AUC
   Answer: D. General CF is evaluated by rating error (RMSE, MAE). (Key point: Evaluation)

4. Which is a data example for one-class CF?
   A. Movie star ratings 1 to 5
   B. Exam marks
   C. Product purchases and page views
   D. Temperature readings
   Answer: C. They are implicit, positive-only and plentiful but noisy. (Key point: Data example)

## Related in Information System

- [One-class vs multi-class CF](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Acollaborative-filtering-one-vs-multi-class) — Information System, chapter 7
- [Cold start in collaborative filtering](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Acold-start-collaborative-filtering) — Information System, chapter 7, asked 2×
- [Collaborative filtering concept](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Acollaborative-filtering-concept) — Information System, chapter 7
- [Short note: collaborative filtering](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Ashort-note-collaborative-filtering) — Information System, chapter 7

## Related in other subjects

- [Intranet vs Internet, firewall, content filtering](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aintranet-internet-benefits-firewall) — Internet and Intranet, chapter 1
- [Compare AM systems; one method of DSB-FC generation](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Aam-types-compare-dsbfc-method) — Communication Systems, chapter 2
- [Content filtering vs packet filtering](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Acontent-filtering-packet-filtering) — Internet and Intranet, chapter 5