---
title: "Link analysis for the web"
subject: "Information System"
chapter: 7
key: "semester_8/information_system:link-analysis-web-environment"
source: https://www.bctengineer.com/q/semester_8/information_system/link-analysis-web-environment
site: BCT Engineering
---

# Link analysis for the web

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

- Asked in: 2074 Bhadra, 6 marks; 2070 Bhadra, 4 marks; 2072 Magh, 3 marks; 2073 Magh, 4 marks (asked 4 times)
- Video: [LINK ANALYSIS : PAGE RANKING ALGORITHM || #informationsystem #pagerank #algorithm](https://www.youtube.com/watch?v=YZGQhwrYQFg) — Easy Explanation
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/information_system/link-analysis-web-environment
- Whole chapter: https://www.bctengineer.com/md/semester_8/information_system/chapter-7

## Question

Explain link analysis for the web based environment with example.

## Short answer

Link analysis studies web hyperlinks (pages as nodes, links as edges) to find important pages. In-links are votes, with more weight from important pages. For a three-page example, PageRank with damping factor 0.85 gives: B≈1.19, A≈1.16, C≈0.64.

## Answer

**Link analysis** is a technique that studies the hyperlinks between web pages (the web graph) to find which pages are important, how pages are related and how communities form. A web page is a **node** and a hyperlink is a **directed edge**. A link from page A to B is treated as a vote, or recommendation, for B.

#### Basic ideas
- **In-links (back-links)** to a page show its popularity.
- **Out-links** show what the page points to.
- Links from important pages count more than links from unknown pages.
- The anchor text of a link describes the target page.

#### Main algorithms
1. **PageRank:** the rank of a page depends on the number and the rank of the pages linking to it: PR(A) = (1-d) + d × Σ PR(Ti)/C(Ti), where d is the damping factor (about 0.85) and C(Ti) is the number of outgoing links of Ti.
2. **HITS (Hubs and Authorities):** a *hub* is a page pointing to many good authorities; an *authority* is a page pointed to by many good hubs. Scores are updated iteratively.
3. **Co-citation and bibliographic coupling** for finding related pages.

#### Example
```text
   A --> B
   A --> C
   C --> B
   B --> A
```
B has two in-links (from A and C), so it is the most important page. A has only one in-link, but it comes from B, the most important page, which gives its whole vote to A, so A is also ranked well. C's only in-link comes from A, which splits its vote between B and C, so C is the least important. Solving the PageRank equations with d = 0.85 gives PR(B) ≈ 1.19, PR(A) ≈ 1.16 and PR(C) ≈ 0.64.

#### Applications
Ranking search results (Google), crawling priority, detecting web spam and link farms, finding communities and social network analysis, and measuring the influence of sites and authors.

#### Limitations
Spam links can be created artificially, new pages have few links, and old pages have an advantage.

## Check yourself

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

1. In link analysis, how is the web modelled?
   A. Pages are edges and users are nodes
   B. Servers are nodes and cables are edges
   C. Words are nodes and pages are edges
   D. Pages are nodes and hyperlinks are directed edges
   Answer: D. The web graph has pages as nodes and hyperlinks as directed edges. (Key point: Web graph)

2. How is a link from page A to page B treated?
   A. As a vote against B
   B. As a copy of A's content into B
   C. As a vote or recommendation for B
   D. As a sign that A is less important
   Answer: C. Links are treated as recommendations for the target page. (Key point: Link as vote)

3. In PageRank, what makes a page rank higher?
   A. Having many out-links
   B. Links from many important pages
   C. Having a long page title
   D. Being the oldest page on the web
   Answer: B. Rank depends on the number and rank of the pages linking in. (Key point: PageRank idea)

4. In HITS, what is a hub?
   A. A page pointing to many good authorities
   B. A page pointed to by many hubs
   C. A page with no links
   D. A page with the most text
   Answer: A. An authority is pointed to by good hubs; a hub points to good authorities. (Key point: HITS)

## Related in Information System

- [Link analysis in web vs cloud](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Alink-analysis-web-vs-cloud) — Information System, chapter 7
- [Link analysis and search engine architecture](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Alink-analysis-search-engine-architecture) — Information System, chapter 7

## Related in other subjects

- [Virtual hosting types; name-based steps](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Avirtual-hosting-types-named-steps) — Internet and Intranet, chapter 4, asked 2×
- [Numerical: 10 km link feasibility with Okumura](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Aokumura-link-feasibility) — Wireless Communication, chapter 3
- [Appropriate, intermediate and labor-based technology for LDCs](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Aappropriate-intermediate-labor-ldc) — Technology, Environment and Society, chapter 1, asked 2×
- [Web-mail to POP3 message transfer protocols](https://www.bctengineer.com/question.md?key=semester_8%2Finternet_and_intranet%3Aalice-bob-email-protocols) — Internet and Intranet, chapter 3