> And if the majority of users are only looking at results
> from one resource... why do a broadcast multi-server
> search in the first place?
More than just a theoretical concern. Consider this from an article by Nina McHale:
"[R]eference and instruction staff at Auraria were asked to draw up a list of ten or so resources that would be included in a general-focus “Quick Search” . . . [h]owever, in practice, the result was disappointing. The results returned from the fastest resource were the results on top of the pile, and of the twelve resources chosen, PsycINFO routinely returned results first. Reference and instruction staff rightly felt that this skewed the results for a general query." [1]
One library' perspective, and I'm pretty sure they were not using Muse. But conceptually the concern would be the same.
--Dave
[1] http://webserviceslibrarian.blogspot.com/2009/01/why-reference-and-instruction.html
==================
David Walker
Library Web Services Manager
California State University
http://xerxes.calstate.edu
________________________________________
From: Code for Libraries [[log in to unmask]] On Behalf Of Jonathan Rochkind [[log in to unmask]]
Sent: Wednesday, May 19, 2010 12:45 PM
To: [log in to unmask]
Subject: Re: [CODE4LIB] Multi-server Search Engine response times: was - OASIS SRU and CQL, access to most-current drafts
Wait, but in the case you suspect is common, where you return results as
soon as the first resource is returned, and subsequent results are added
to the _end_ of the list....
I'm thinking that in most of these cases, the subsequent results will be
several pages "in", and the user will never even get there. And if the
majority of users are only looking at results from one resource... why
do a broadcast multi-server search in the first place?
Peter Noerr wrote:
> However things are a bit different now... At the risk of opening the debate once more and lots of lengthy discussion let me say that our experience (as one of the handful of commercial providers of "multi-server search engines" (MSSEs? - it'll never stick, but I like it)) is:
>
> 1) Times are not slow for most installations as they are set by default to provide incremental results in the fashion Jakub suggests ("First In, First Displayed"). So users see results driven by the time of the fastest Source, not the slowest. <contentious statement>This means that, on average, getting the results from a MSSE can be faster than doing the same search on all of the native sites (just talking response times here, not the fact it is one search versus N). Do the maths - it's quite fun. </contentious statement>
>
> 2) The average "delay" for just processing the results through modern MSSEs is about 0.5 sec. Add to this say another 0.2 for two extra network hops and the additional response time to first display is about 3/4 of a second. This is a time shift all the way down the set of results - most of which the user isn't aware of as they are beyond the first 10 on screen, and the system allows interaction with those 10 while the rest are getting their act together. So, under 1 second is added to response times which average about 5 seconds. Of course, waiting for all the results adds this time to the slowest results.
>
> 3) Most users seem happy to get things back faster and not worry too much about relevance ranking. To combat the response time issue for users who require ranked results, the incremental return can be set to show interfiled results as the later records come in and rank within the ones displayed to the user. This can be disconcerting, but making sure the UI doesn't lose track of the user's focus is helpful. Another option is to show that "new results" are available, and let the user manually click to get them incorporated - less intrusive, but an extra click!
>
> General experience with the incremental displays shows that users are happiest with them when there is an obvious and clear reason for the new additions. The most accepted case is where the ranking criterion is price, and the user is always happy to see a cheaper item arrive. It really doesn't work well for titles sorted alphabetically - unless the user is looking for a specific title which should occur at the beginning of the list. And these examples illustrate the general point - that if the user is focused on specific items at the top of the list, then they are generally happy with an updating list, if they are more in "browse" mode, then the distraction of the updating list is just that - a distraction, if it is on screen.
>
> Overall our experience from our partner's users is that they would rather see things quickly than wait for relevance ranking. I suspect partly (can of worms coming) because the existing ranking schemes don't make a lot of difference (ducks quickly).
>
> Peter
>
> Peter Noerr
> CTO, Museglobal
> www.museglobal.com
>
>
>> -----Original Message-----
>> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of
>> Walker, David
>> Sent: Tuesday, May 18, 2010 12:44 PM
>> To: [log in to unmask]
>> Subject: Re: [CODE4LIB] OASIS SRU and CQL, access to most-current
>> drafts
>>
>>
>>> in order to provide decent user experience you need to be
>>> able to present some results "sooner" than others.
>>>
>> I would actually question whether this is really necessary.
>>
>> A few years back, I did a big literature review on metasearch, as well
>> as a looked at a good number of usability studies that libraries did
>> with metasearch systems.
>>
>> One thing that stood to me out was that the literature (written by
>> librarians and technologists) was very concerned about the slow search
>> times of metasearch, often seeing it as a deal-breaker.
>>
>> And yet, in the usability studies, actual students and faculty were far
>> less concerned about the search times -- within reason, of course.
>>
>> I thought the UC Santa Cruz study [1] summarized the point well: "Users
>> are willing to wait as long as they think that they will get useful
>> results. Their perceptions of time depend on this belief."
>>
>> Trying to return the results of a metasearch quickly just for the sake
>> of returning them quickly I think introduces other problems (in terms
>> of relevance ranking and presentation) that do far more to negatively
>> impact the user experience. Just my opinion, of course.
>>
>> --Dave
>>
>> [1]
>> http://www.cdlib.org/services/d2d/metasearch/docs/core_ucsc_oct2004usab
>> ility.pdf
>>
>> ==================
>> David Walker
>> Library Web Services Manager
>> California State University
>> http://xerxes.calstate.edu
>> ________________________________________
>> From: Code for Libraries [[log in to unmask]] On Behalf Of Kuba
>> [[log in to unmask]]
>> Sent: Tuesday, May 18, 2010 9:57 AM
>> To: [log in to unmask]
>> Subject: Re: [CODE4LIB] OASIS SRU and CQL, access to most-current
>> drafts
>>
>> That is quite unfortunate, as we were looking at SRU 2.0 as a possible
>> candidate for the front-end protocol for Index Data's pazpar2. The
>> main problem with federate/broadcast/meta (however you want to call it
>> ;) searching is that the back-end databases are scattered in different
>> locations or simply slow in their response times and in order to
>> provide decent user experience you need to be able to present some
>> results "sooner" than others. Waiting for the slowest database to
>> respond is usually not an option.
>>
>> On Tue, May 18, 2010 at 5:24 PM, Ray Denenberg, Library of Congress
>> <[log in to unmask]> wrote:
>>
>>> On 18 May 2010 15:24, Ray Denenberg, Library of Congress
>>>
>> <[log in to unmask]>
>>
>>> wrote:
>>>
>>>> There is no synchronous operation in SRU.
>>>>
>>> Sorry, meant to say "no asynchronous .....
>>>
>>> --Ray
>>>
>>>
>>
>> --
>>
>> Cheers,
>> Jakub
>>
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