Hi - I'm wondering if she is using a definition of "database" that seems to be common in libraries, that means "a resource on the web that we pay for".

D

-----Original Message-----
From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of Alain Borel
Sent: Friday, June 03, 2011 10:24 AM
To: [log in to unmask]
Subject: Re: [CODE4LIB] Precision and Recall

Dave Caroline <[log in to unmask]> a écrit :
> The questions seem related to search engines or should you be googling 
> for full text indexes or the other more correct name inverted index.
> Because in the normal scheme of events databases return exactly what 
> you ask for.

One could argue that the same thing happens with search engines. After all, both databases and search engines are deterministic programs that provide a set of records in response to a query.

Precision and recall are not determined by what you ask - what defines them is how relevant the output records are with respect to a real-life question. It isn't tied to a technology. Of course, it can be more or less difficult to translate this question into a query, and the program might be more or less "smart" while processing the query.  
Both aspects affect precision and recall, in my opinion.

Anybody who ever used a bibliographic database using Google-like queries can testify that a database can have extremely poor precision and recall in some use cases ;-)

Best regards,
Alain Borel
EPFL Bibliothèque
Rolex Learning Center
1015 Lausanne (Switzerland)