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# Questions tagged [information-retrieval]

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### Statistical classification of text

I'm a programmer without statistical background, and I'm currently looking at different classification methods for a large number of different documents that I want to classify into pre-defined ...
9k views

### Measuring Document Similarity

To cluster (text) documents you need a way of measuring similarity between pairs of documents. Two alternatives are: Compare documents as term vectors using Cosine Similarity - and TF/IDF as the ...
3k views

### Difference between Log Entropy Model and TF-IDF Model?

I would like to understand what are the differences/advantages in using TF-IDF or the Log Entropy model for represeting documents and queries in an information retrieval system using diferent weights. ...
2k views

### Can one use Cohen's Kappa for two judgements only?

I am using Cohen's Kappa to calculate the inter-agreement between two judges. It is calculated as: $\frac{P(A) - P(E)}{1 - P(E)}$ where $P(A)$ is the proportion of agreement and $P(E)$ the ...
11k views

### Mean Average Precision vs Mean Reciprocal Rank

I am trying to understand when it is appropriate to use the MAP and when MRR should be used. I found this presentation that states that MRR is best utilised when the number of relevant results is less ...
459 views

### Why does Lucene IDF have a seemingly additional +1?

From the Lucene docs $\text{IDF} = 1 + \log\left(\frac{\text{numDocs}}{\text{docFreq}+1}\right)$ In other references (i.e. wikipedia), IDF is typically calculated as \$\log\left(\frac{\text{numDocs}}{...
837 views

### Dataset and papers for baseline [closed]

I'm doing a project about Topic Detection and Tracking in text. I need to perform a baseline so I can compare existing results with mine. I read some papers where they use datasets that are not so ...
470 views

### Vector Space Model for Online News Clustering

I am trying to automatically cluster news articles based on their content. I need this algorithm to be online and simply group news articles related to the same story as they arrive. The common ...
75 views

### Is there a ranking metric based on percentages that favors larger magnitudes?

I have two groups, "in" and "out," and item categories that can be split up among the groups. For example, I can have item category A that is 99% "in" and 1% "out," and item B that is 98% "in" and 2% "...