I see three classes of 'time period' tags that we need to discuss, and

1. want to assess each of them in the context of what is needed of a tag
2. talk a little about an alternative approach that JanMurphy raised.

#What is needed from a tag?#

In various places, we are told:

• Tags are a map of what our community is about/not about (and so implicitly about allowed and disallowed topics)

• Tags are for organising (not summarising) content, to group questions into specific well-defined categories, so that:

  • experts can find suitable questions they might answer
  • those looking for answers can find potentially-related material that might address their need
  • users can filter their view of the site to highlight material of particular interest/downplay material of little or no interest

• The most-popular (or only) tag on a question is used for SEO purposes (prepended to the page title in search engine results) -- worth noting, this can reduce the amount of a question title that is visible significantly for long tag names.

• Tags must work as the only tag on a question.

(All this is irrespective of how people choose to be alerted to new content -- newsletters, rss feed or whatever-- the medium doesn't affect the purpose of tags).

#Classes of 'time period' tags#

The three classes of 'time period' tags I suggest we discuss are:

1. 'Named' time-periods e.g. world-war-1, world-war-2, us-civil-war
2. 'Century' tags e.g. 18th-century, 19th-century
3. 'Decade' tags e.g. 1840s, 1790s

For comparison purposes, history.stackexchange.com make much more use or Class 1 (Named periods) than we do. They use century tags, but most of them are not high up on the list of popular tags (which mitigates some of their disadvantages). They use decade tags very sparely, and only for the 20th century (I'm guessing there are fewer widely-recognised 'Named periods' in the 20th-century.)

#Assessment of current time-period tagging aproach#

1. 'Named' time-periods e.g. world-war-1, world-war-2, us-civil-war

We use these for questions related to events that took place in a widely-recognised named period, and/or records that were created specifically during such periods.

Allowed/disallowed topics?

Yes (except the absence of a tag for a particular named period doesn't make it automatically off-topic, just not asked about yet.)

Useful to organise material?

Yes (and there doesn't seem to be tendency to use them to summarise rather than organise).

Meaningful and helpful as the first element of a Search engine result?

Yes, because of the degree of specificity involved.

Works as a lone tag in a Genealogy context?

No. Usually a geographical tag is necessary as well, as well as a more a genealogy-specific tag, but that applies to most of our questions.

Conclusion

'Named time-period' tags (IMO) are good, useful specific tags and should remain. And we could extend this class of tags when necessary (e.g. middle-ages, french-revolution).

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2. 'Century' tags e.g. 18th-century, 19th-century

We use these for questions about events and/or records created in the relevant century, or people who lived in that century.

Allowed/disallowed topics?

Not really helpful, as any century for which there are genealogical records available is on topic. Plus, they're based on a western-centric calendar and we don't want to discourage questions based on other calendars (hoping the relevant experts will show up to answer them).

Useful to organise material?

Possibly, although the availability of genealogical records in any particular place rarely aligns with a century boundary

They might be useful as a very-high-level categorisation so that people can filter out noise about centuries that aren't relevant to their interests/expertise. However, there's a tendency to add a century-tag to every question, because they exist, even if it's just summarising the question (not always accurately) rather than categorising it.

Meaningful/helpful in Search engine results?

I say not. They're likely to be among the most popular tags (because they're ubiquitous) so will end up at the front of many results and displace a more relevant tag; even though they're rarely the most important thing about a question.

Also, the time period in question is almost certain to be specified in the title or body of the question and so affect the search results.

Works as a lone tag in a Genealogy context?

No. Usually a geographical tag is necessary as well, as well as a more a genealogy-specific tag, but that applies to most of our questions.

Conclusion

I'm in two minds about 'Century' tags.

There's a tendency to use them because they're there and 'must therefore be useful' but this leads to a number of drawbacks (especially in search engine results).

They could have some utility for high-level filtering. Wen our traffic volume goes up, I'll probably concentrate on 18th, 19th and 20th century in England and Wales, for example -- it's a high-level filter but will cut out most of what I can't help with. But then so would just filtering by England and Wales... But I recognise the same approach might not be true for other geographies -- an American genealogist whose ancestors immigrated in the nineteenth century may not be interested in sixteenth and seventeenth century colonists and immigrants, or their records.

IMO, we wouldn't suffer if we significantly reduced the use of century tags as long as we used other more 'intelligent' tagging approaches, but I'm not sure we're ready for the re-tagging workload that would involve; and there are cases where they are an appropriate distinction. We should certainly discourage using a Named-Period and Century-Period tag on the same question -- one makes the other redundant. (Note: using a mixture of 'Century' and 'Named' tags will potentially increase the number of tags an individual will need to monitor.)

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3. 'Decade' tags e.g. 1840s, 1790s

We use these for questions events and/or records created in the relevant decade, or people who lived in that decade.

Allowed/disallowed topics?

Not really helpful, for the same reasons that century tags fail this test.

Useful to organise material?

Much less so even than century tags, and for the same reasons.

In particular the range of expertise of an individual is very unlikely to be restricted to a single (or small group of) decade(s).

It's been said that (multiple) decade tags help narrow down searches, but that only works for 2 or three decades. If a question spans 4 decades or more it may not show up in your search because there isn't room for 4 decade tags plus a geography tag and a tag that's really useful to categorise the question! And if search results aren't consistently useful, they're no use at all. (If you really want to search on a specific date range mentioned in a question, Google is a much better way of doing this, and it brings up answers as well as questions).

Meaningful/helpful in Search engine results? No. This is almost never the most important thing about a question, but again they're ubiquitous.

Works as a lone tag in a Genealogy context?

No, for the same reasons as all other time-period tags.

Conclusion

As you can probably guess, I think we should ditch 'decade' tags, as they serve no good purpose that can't be met in another way, thus freeing up 'tagroom' for more useful categorisation (and possibly even making people think more carefully about the right tags to use). And if they are retained, they should be used instead of the other time-period tags, not alongside them. And we should be vigilant to retag questions where another period-tag is more useful.

#Is there a better way?#

To address Jan's questions about 'Is there a better way' [rather than using calendar-based time periods such as centuries]?

Well, yes, sometimes, but it would involve a lot of work (including -- ta-da -- creating new tags, improving our tag-wiki and re-tagging questions) but IMO the payback would be worth it. (and better to do it now than later when the workload would be worse).

An example of where I think a calendar-based tag isn't a good solution, even if the question relates to a specific period, is:

How did the information gathered for civil registration vary with time in England and Wales.

Right now, to categorise that question you'd need the following tags:

england and wales (as civil registration was the same across both countries). You can't use united-kingdom because things differed in N. Ireland and Scotland (as well as sundry islands around these shores).

19th-century, 20th-century and 21st-century to cover the time span of interest (recognising that the first 37-and-a-bit years of the 18th century not relevant).

vital-records because it includes all of birth-records death-records and marriage-records. (You might argue that the question should be split by record type, but that would involve an awful lot of repetition in the answers).

That's six tags, so which do I lose? Geography is essential. Vital records is essential. So I have to ditch all the time periods as just losing one of them would be misleading... And then people following by time periods would perhaps never see my question.

I think a much better solution would be to tag it civil-registration england wales. Those three tags (combined with a good tag wiki that specifically identifies the period during which Civil Registration has taken place in England and Wales) categorise the question completely.

Or even: civil-registration-england-wales. That would allow the tag wiki to be very specific, but it is a long tag which would affect search engine results. However, civil-registration could get very unwieldy if it had to cover all geographies, which would make it mush less likely to be useful (or even to get created). And of course this approach could be generalised.

But sometimes a time period is the right thing to use, even with a specific record type.

What information would I find in a Wiltshire parish register baptism entry for the early 19th century?

I'd tag that with:

baptism-records -- no need for parish-register as baptism-records is more specific.

wiltshire ( there might be local record keeping practices) -- it might get retagged to include england as well and possibly lose wiltshire if an expert deemed though the more general tag was applicable instead (i.e. there were no local peculiarities of note).

nineteenth-century -- broad time classification. There is a distinction in the records pre- and post-1812, but a good answer would include that anyway, and somebody asking the question may not know that break-point.

And sometimes we can't be specific about record-type either:

Looking for the birth-date of Fred Bloggs in England around 1865?

Thing-place-time again:

birth-records england nineteenth-century.

#In summary#

What we have right now is a reductionist approach to tagging for time-period (century/decade building blocks) combined with the sparse use of more 'intelligent' Named-period tags. This severely reduces the tagroom available for more important tags and (as others have pointed out) leads to redundant and/or misleading tagging as well as poor search-engine presentation.

What we should have is a simplified set of basic building blocks for use when nothing more specific is relevant (centuries and other major calendar divisions relevant to non-Western calendars); plus an increased set of Named-period tags (created as they're required) plus more specific record-type tags that include geography explicitly and time-period implicitly.