Showing posts with label Information Retrieval. Show all posts
Showing posts with label Information Retrieval. Show all posts

Saturday, June 19, 2021

Information Retrieval MCQs with Answers home page

Information retrieval multiple choice questions with answers, IR MCQs with answers, solved information retrieval questions, information retrieval objective type questions with solutions, information retrieval exam questions

Information Retrieval Multiple Choice Questions with Answers

  • Information Retrieval MCQs with Answers - SET 08

  • Information Retrieval MCQs with Answers - SET 09

  • Information Retrieval MCQs with Answers - SET 10

  • Information Retrieval MCQs with Answers - SET 11

  • Information Retrieval MCQs with Answers - SET 12

  • Information Retrieval MCQs with Answers - SET 13

  • Information Retrieval MCQs with Answers - SET 14

  • Information Retrieval MCQs with Answers - SET 15




 

Keywords

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Friday, June 18, 2021

List down the local methods for improving recall of IR systems

What are the local methods to improve recall in a retrieval system, relevance feedback, pseudo relevance feedback methods to improve recall, local methods for query reformulation in IR system

 

Question:

List down the local methods for improving recall of IR systems

 

Answer:

Local methods go for local on-demand analysis for a user query in order to improve recall of a retrieval system. Following are the local methods for improving recall;

1. Relevance feedback

It improves the query based on user feedback on relevance of the documents in the initial set of results. Users were asked explicitly to mark the documents as relevant or non-relevant. This feedback is used to reformulate the query to produce new search results.

2. Pseudo relevance feedback

Pseudo relevance feedback, also known as blind relevance feedback, provides a method for automatic local analysis. It automates the manual part of relevance feedback, so that the user gets improved retrieval performance without an extended interaction.

3. Indirect relevance feedback

 

 

Related links/questions

 

 

             

Keywords

Relevance feedback in information retrieval

Pseudo relevance feedback in information retrieval

Evaluation of information retrieval systems

Local methods for query reformulation

IR techniques for relevance feedback

Relevance feedback and query reformulation in IR

Query expansion techniques for information retrieval


List down the common global resources for query expansion

List down the global resources applicable for query expansion, what are the resources useful for query expansion or query reformulation, how does query expansion is achieved? global method for improving recall of an information retrieval system

 

Question:

List down the common resources for query reformulation / expansion

 

Answer:

Query expansion is a global method for query reformulation. It is used for adding related words to a query in order to increase the number of returned documents and improve recall accordingly. It often referred as “global query expansion”. As the method uses global resources such as thesaurus and query logs that are not usually query dependent, it is referred to as “global query expansion”. Query expansion uses the following global resources for query reformulation;

1. Controlled vocabulary

There is a canonical term for each concept; all other terms for the same concept are replaced by the canonical term

2. Manual thesaurus

Human annotators build sets of synonymous terms for concepts. Example: PubMed.

3. Automatically generated thesaurus

Attempt to generate a thesaurus automatically by analyzing the distribution of words in documents

4. Query log mining

Query logs are maintained by each search engine in order to analyze the behavior of the user while interacting with search engine. These kind of approaches use these query logs to analyze the user’s preference and adds corresponding terms to query.

 

 

Related links/sources

 

 

 

Keywords

Query expansion techniques

Query expansion methods in information retrieval

Query expansion techniques for question answering

Query expansion to improve document retrieval

Global query expansion how to do

Global methods for improving recall of an IR system

Improve the effectiveness of information retrieval

Global option for improving the recall

What is global query expansion?

Why query expansion is referred to as global method?

 

 

How to improve the recall of an information retrieval system

How to improve the recall of an IR system, what are the different methods available to improve the search recall? State the global method and local method for effective recall.

Question:

How to increase recall in information retrieval?

 

Answer:

Recall is the fraction of relevant documents that are retrieved. By modifying the initial query, we can improve the recall. This can be done as follows;

1. By adding new terms to the original query terms that are semantically related to the terms of the original query. This is referred as global method.

2. By making the query vector more similar to vectors of relevant documents. We need some indication of relevance either provided by the user or assumed by the model. This approach is referred as local method.

 

 

Related links/questions

 

 

 

 

Keywords

How to improve recall in information retrieval

Recall formula in information retrieval

How to evaluate information retrieval system

How to improve precision and recall

Information retrieval system evaluation

How do you evaluate an IR system

Improving the effectiveness of information retrieval system

Monday, June 14, 2021

Calculate the TF-IDF weight for tems of a given document

Find the TF-IDF of terms of a given document and a collection of documents, how to calculate tf-idf, the use of tf-idf in finding the importance of a term in a document, term frequency-inverse document frequency

Question:

Given a document X containing terms t1, t2 and t3 with frequencies (inside brackets) as follows;

t1(3), t2(2), t3(1)

Let us assume that the collection contains 10,000 documents and document frequencies of these terms are as follows;

t1(50), t2(1300), t3(250)

Then, find the TF-IDF weight of terms t1, t2, and t3 in the document X.

 

Solution:

TF-IDF (Term Frequency-Inverse Document Frequency) is a measure to calculate “how relevant a term is in a given document”.

TFt,d counts the number of times a term t occurs in a document d. It can be calculated as follows;


For example, if the document D1 contains the term ‘quick’ 10 times, and it has 54 words in it, then the TF’quick’, D1 = 10/54 = 0.19.

DFt refers to the number of documents in which t presents.

For example, if 120 documents consist of the word ‘quick’, then the DF’quick’ = 120.

IDFt is the inverse measure used to calculate the informativeness of the given term t. This means, how common or rare a word is in the entire document set. The closer it is to 0, the more common a word is. This can be calculated as follows;


Here, N is the number of documents in the given collection, and DFt is the document frequency of term t.

The TF-IDF weight of a term is the product of its TF weight and its IDF weight.

TF-IDF for term t1;

TFt1 = (number of times t1 occurs in X)/(number of words in X) = 3/3

IDFt1 = log(No. of docs in the collection/No. of docs t1 appears) = log(10000/50) = 5.3

TF-IDF for t1 = 5.3

 

TF-IDF for term t2;

TFt2 = 2/3

IDFt2 = log (10000/1300) = 2.0

TF-IDF for t2 = 1.3

 

TF-IDF for term t3;

TFt3 = 1/3

IDFt3 = log (10000/250) = 3.7

TF-IDF for t3 = 1.23

 

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how to find term frequency? how to find inverse document frequency? how to calculate tf-idf weight? what is the importance of tf-idf weights? solved exercise in information retrieval, define term frequency, define document frequency, define inverse document frequency


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