In a meeting today I participated in a discussion about search (specifically searching of community resources of course). In the discussion we realized there was a lack of clarity on the difference between a scoped search and a filtered search - depending on who you asked they were either the same thing or very different. So I did a little research, and here are my findings.
The Problem Statement
Here are a few variations of the positions in the meeting:
- Is scoping the same as filtering?
- Is scope something you pass into a search and filter is something you do with the result set to reduce it?
- Is scope the limitation of a search to a specific set of resources, and filter is a way of excluding content based on content attribution?
Research
According to Dictionary.com, scope is:
scope (n.)
1. The range of one's perceptions, thoughts, or actions.
2. Breadth or opportunity to function. See Synonyms at room.
3. The area covered by a given activity or subject. See Synonyms at range.
4. The length or sweep of a mooring cable.
5. Informal. A viewing instrument such as a periscope, microscope, or telescope.
Also according to Dictionary.com, filer is:
fil·ter (n.)
1.
a. A porous material through which a liquid or gas is passed in order to separate the fluid from suspended particulate matter.
b. A device containing such a material, especially one used to extract impurities from air or water.
2.
a. Any of various electric, electronic, acoustic, or optical devices used to reject signals, vibrations, or radiations of certain frequencies while allowing others to pass.
b. A colored glass or other transparent material used to select the wavelengths of light allowed to reach a photosensitive material.
3. Computer Science. A program or routine that blocks access to data that meet a particular criterion: a Web filter that screens out vulgar sites.
I continued to search around looking at other resources. Here are a couple of other references:
UseIt.com - Scoped Search: Sometimes special areas of a site are sufficiently coherent and distinct from the rest of the site that it makes sense to offer a scoped search: restricted to search that subsite only (the search scope).
Panoptic Search says, "...scoped search achieves a similar effect to the Google site:query operator, but allows specification of a comma-separated list of sites to be included or excluded."
Summary
My assessment, which of course should be taken as the final and authoritative word on the topic, is that scoping is the act of limiting a search to a set of resources (websites, sub-sites, etc.) while filtering is the act of excluding content based on contextual things, such as attribution or keywords. An example would be:
Search only dotnetjunkies.com and sqljunkies.com for the term "SqlDataAdapter" and return only content that included code in C#
In this example, the query term is "SqlDataAdapter", the scope is dotnetjunkies.com and sqljunkies.com, and the filter is only content with C# code.
There it is, the definitive difference between a scoped search and a filtered search, and how they can work together.