DBpedia Release Evaluation
The Quality Assessment Framework (QAF) is developed to document the quality of the knowledge base and furthermore the progress of DBpedia's extraction framework. The main idea of the QAF is a comparison between a manually created best-case dataset (Gold Standard) and the output from DBpedia's ontology based extraction. The QAF estimates the precision of the extraction framework and the completeness (recall) of DBpedia compared to its source Wikipedia.
Gold Standard & Mappings
For a significant evaluation, only potentially extractable triples are considered. Only if a triple arise from a mapped property it can be extracted. Here this triples are called mapped triples. The following table shows the total number of triples in the Gold Standard, the number of mapped triples and the percentage of mapped triples for each category. The categories result from different patterns in which the information is given in Wikipedia infoboxes. The number of cases differ in a high extent depending on the category. The results for the categories based on small numbers should be handled with care.
| Category | Gold Triples | DBpedia Release | |||||
|---|---|---|---|---|---|---|---|
| DBpedia 3.5.1 | DBpedia 3.6 | DBpedia 3.7 | |||||
| Mapped Triples | % | Mapped Triples | % | Mapped Triples | % | ||
| Total | 3221 | 1504 | 46.7 | 1522 | 47.3 | 1732 | 53.8 |
| Plain Property | 893 | 514 | 57.6 | 521 | 58.3 | 599 | 67.1 |
| Number-Unit | 76 | 51 | 67.1 | 52 | 68.4 | 57 | 75.0 |
| Coordinate | 54 | 36 | 66.7 | 39 | 72.2 | 48 | 88.9 |
| Interval | 31 | 22 | 71.0 | 22 | 71.0 | 24 | 77.4 |
| List | 801 | 478 | 59.7 | 482 | 60.2 | 560 | 69.9 |
| One-Property-Table | 447 | 242 | 54.1 | 244 | 54.6 | 236 | 52.8 |
| Multi-Poprty-Table | 625 | 83 | 13.3 | 83 | 13.3 | 109 | 17.4 |
| Open Property | 139 | 13 | 9.4 | 13 | 9.4 | 16 | 11.5 |
| Open Property Table | 26 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Internal Template | 116 | 58 | 50.0 | 59 | 50.9 | 76 | 65.5 |
| Merged Properties | 13 | 7 | 53.8 | 7 | 53.8 | 7 | 53.8 |
Evaluation Results
The following two tables show the completeness (recall) and precision of the different release versions. To achieve comparability and to clean the results from the effect of more and better mappings, the mapping version of the 3.5.1 release is taken as constant.
| Category | DBpedia 3.5.1 | DBpedia 3.6 | DBpedia 3.7 |
|---|---|---|---|
| Total | 45.7% | 60.2% | 61.8% |
| Plain Property | 80.5% | 83.7% | 86.0% |
| Number-Unit | 68.6% | 68.6% | 66.7% |
| Coordinate | 100.0% | 100.0% | 100.0% |
| Interval | 72.7% | 68.2% | 72.7% |
| List | 33.9% | 75.7% | 77.8% |
| One-Property-Table | 5.4% | 5.8% | 5.8% |
| Multi-Poprty-Table | 0.0% | 0.0% | 0.0% |
| Open Property | 23.1% | 23.1% | 30.8% |
| Open Property Table | na | na | na |
| Internal Template | 8.6% | 10.3% | 10.3% |
| Merged Properties | 57.1% | 57.1% | 71.4% |
| Category | DBpedia 3.5.1 | DBpedia 3.6 | DBpedia 3.7 |
|---|---|---|---|
| Total | 91.2% | 92.3% | 92.4% |
| Plain Property | 96.3% | 96.6% | 97.4% |
| Number-Unit | 85.4% | 85.4% | 85.0% |
| Coordinate | 100.0% | 100.0% | 100.0% |
| Interval | 100.0% | 100.0% | 88.9% |
| List | 91.5% | 92.8% | 93.2% |
| One-Property-Table | 32.5% | 36.8% | 34.1% |
| Multi-Poprty-Table | na | na | na |
| Open Property | 100.0% | 100.0% | 100.0% |
| Open Property Table | na | na | na |
| Internal Template | 83.3% | 75.0% | 75.0% |
| Merged Properties | 80.0% | 80.0% | 100.0% |
