computer science

Link analysis

Link analysis is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Link analysis rather than just read about it. In short: In network theory, link analysis is a data-analysis technique used to evaluate relationships between nodes. Relationships may be identified among various types of nodes, including organizations, people and transactions.

Key takeaways

Link analysis belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Link analysis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Link analysis from memory before moving on to harder problems.

Reference excerpt

In network theory, link analysis is a data-analysis technique used to evaluate relationships between nodes. Relationships may be identified among various types of nodes, including organizations, people and transactions. Link analysis has been used for investigation of criminal activity (fraud, counterterrorism, and intelligence), computer security analysis, search engine optimization, market research, medical research, and art.

Knowledge discovery Knowledge discovery is an iterative and interactive process used to identify, analyze and visualize patterns in data. Network analysis, link analysis and social network analysis are all methods of knowledge discovery, each a corresponding subset of the prior method. Most knowledge discovery methods follow these steps (at the highest level):

Data processing Transformation Analysis Visualization Data gathering and processing requires access to data and has several inherent issues, including information overload and data errors. Once data is collected, it will need to be transformed into a format that can be effectively used by both human and computer analyzers. Manual or computer-generated visualizations tools may be mapped from the data, including network charts. Several algorithms exist to help with analysis of data – Dijkstra's algorithm, breadth-first search, and depth-first search. Link analysis focuses on analysis of relationships among nodes through visualization methods (network charts, association matrix). Here is an example of the relationships that may be mapped for crime investigations:

Link analysis is used for 3 primary purposes:

Find matches in data for known patterns of interest; Find anomalies where known patterns are violated; Discover new patterns of interest (social network analysis, data mining).

History Klerks categorized link analysis tools into 3 generations. The first generation was introduced in 1975 as the Anacpapa Chart of Harper and Harris. This method requires that a domain expert review data files, identify associations by constructing an association matrix, create a link chart for visualization and finally analyze the network chart to identify patterns of interest. This method requires extensive domain knowledge and is extremely time-consuming when reviewing vast amounts of data. In addition to the association matrix, the activities matrix can be used to produce actionable information, which has practical value and use to law-enforcement. The activities matrix, as the term might imply, centers on the actions and activities of people with respect to locations. Whereas the association matrix focuses on the relationships between people, organizations, and/or properties. The distinction between these two types of matrices, while minor, is nonetheless significant in terms of the output of the analysis completed or rendered. Second generation tools consist of automatic graphics-based analysis tools such as IBM i2 Analyst's Notebook, Netmap, ClueMaker and Watson. These tools offer the ability to automate the construction and updates of the link chart once an association matrix is manually created, however, analysis of the resulting charts and graphs still requires an expert with extensive domain knowledge. The third generation of link-analysis tools like DataWalk allow the automatic visualization of linkages between elements in a data set, that can then serve as the canvas for further exploration or manual updates.

Applications FBI Violent Criminal Apprehension Program (ViCAP) Iowa State Sex Crimes Analysis System Minnesota State Sex Crimes Analysis System (MIN/SCAP) Washington State Homicide Investigation Tracking System (HITS) New York State Homicide Investigation & Lead Tracking (HALT) New Jersey Homicide Evaluation & Assessment Tracking (HEAT) Pennsylvania State ATAC Program. Violent Crime Linkage Analysis System (ViCLAS)

Issues with link analysis

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Link analysis

Start with the simplest possible case. Write down what Link analysis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Link analysis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Link analysis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Link analysis

In research: Link analysis appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Link analysis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Link analysis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Link analysis, Network theory, so understanding it makes those chapters shorter.
In everyday life: Look for Link analysis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Link analysis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Link analysis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Link analysis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Link analysis in simple terms?

Why does Link analysis matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Link analysis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Link analysis.