# True (false) positives (negatives), recall rate and precision Definition

Source: Internet
Author: User

True positive (true, TP) is predicted as positive samples by the model;

True negative (true negative, TN) is a negative sample predicted as negative by the model;

False Positive (false positive, FP) is predicted as positive negative samples by the model;

False Negative (false negative, FN) positive samples predicted as negative by the model;

True positive rate (true rate, TPR) or sensitivity)
TPR = TP/(TP + FN)
Number of positive sample prediction results/actual number of positive samples

True negative rate (true negative rate, tnr) or specificity)
Tnr = TN/(TN + FP)
Number of negative sample prediction results/actual number of negative samples

False positive rate (false positive rate, FPR)
FPR = FP/(FP + Tn)
Predicted positive negative sample result count/Actual negative sample count

False negative rate (false negative rate, FNR)
FNR = FN/(TP + FN)
Number of predicted positive sample results/actual number of positive samples

Recall rate and accuracy:

-Documents retrieved by the system ()

-Unrelated documents retrieved by the system (B)

-Related documents not retrieved by the system (c)

-Irrelevant documents retrieved by the system (d)

Intuitively, the more relevant documents retrieved by a good retrieval system, the better. The fewer irrelevant documents, the better.

Recall rate and accuracy are the most important parameters for measuring the performance of information retrieval systems.

Recall rate R: The number of retrieved documents is used as the numerator, and the total number of all relevant documents is used as the denominator, that is, r = A/(A + C)

Precision P:The number of retrieved documents is used as the numerator, and the total number of retrieved documents is used as the denominator. That is, P = A/(A + B ).

 Retrieved A B Not retrieved C D

Related

Unrelated

Related Keywords:

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

## A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

• #### Sales Support

1 on 1 presale consultation

• #### After-Sales Support

24/7 Technical Support 6 Free Tickets per Quarter Faster Response

• Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.