Practical challenges in computing recall

Most experiments are designed on controlled corpus i.e., the precision and recall of the corpus are already known either manually or through some other means (not the same as the experimental tool/automation itself). Thus, these are smaller samples of the real corpus. An Oracle can now be implemented to compute recall. Sampling works in most cases. However, it has its own limitations too. For example, samples can suffer from a serious threat to validity. With another sample, the results could be different. Creating several large samples in several circumstances could be infeasible. Let us review some techniques followed by researchers in these contexts to compute recall.

Gold Sets or Benchmarks

Using an existing benchmark: One way to address this issue is to use a carefully selected representative dataset such as sf100 (http://www.evosuite.org/experimental-data/sf100/). While this is large and unbiased, the issue could be that this is still too large for certain recall computation tasks. Such benchmarks are also referred to as “Gold Set”. Moreover, such benchmarks are rare and specialized that these may not suit your purpose all the time.

Creating your own benchmark: In Shepherd et al.’s paper on “Using Natural Language Program Analysis to Locate and Understand Action-Oriented Concerns”, he hires a new person to prepare the gold set along with relevant results. Another person verifies the results. Both these people discuss and reconcile wherever there were disagreements. This gold set is then released to the community.

Comparative Evaluation instead of Recall

In papers such as “Improving Bug Localization using Structured Information Retrieval”, a comparative result is given instead of recall. They claim that their approach finds x% of bugs more than another tool.

MRR

If there is only one result expected. Computing MRR is more appropriate than Recall. It is easier to do so in top-10 or top-k results.

More on this …soon.

 

 

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