{"id":10,"date":"2013-12-11T22:02:52","date_gmt":"2013-12-11T22:02:52","guid":{"rendered":"http:\/\/www.eversholt.org.uk\/blog\/?p=10"},"modified":"2013-12-11T22:29:28","modified_gmt":"2013-12-11T22:29:28","slug":"the-birthdate-tool-is-born","status":"publish","type":"post","link":"https:\/\/www.eversholt.org.uk\/blog\/the-birthdate-tool-is-born\/","title":{"rendered":"The Birthdate Tool is born"},"content":{"rendered":"

The birthdate tool<\/a> works out when someone might have been born, given their age.<\/p>\n

That doesn’t sound very hard, but turns out to be very tricky. If you find a bug, please leave a post here telling me what dates have gone wrong, and I’ll be very grateful.<\/p>\n

Sometime in in March 2004, I saw the new baby. “Goodness, she’s so beautiful! How old is she?”, I said.<\/p>\n

“She’s two months old”, came the reply.<\/p>\n

OK, when was the baby born?<\/p>\n

I know I asked the question in March 2004. So, on some day between 1 Mar 2004 and 31 Mar 2004, the baby was 2 months old.<\/p>\n

If I had asked the question on 31 Mar 2004, the baby must have been born on or before 31 Jan 2004. If she’d been born on 1 Feb 2004, she’d not be 2 months old on 31 Mar. She’d be “Very nearly 2 months”, or something like that. So the latest possible birthdate for her is 31 Jan 2004.<\/p>\n

If I had asked the question on 1 Mar 2004, the earliest she could have been born is 2 Dec 2003. If she’d been born on 1 Dec 2003, she’d have been 3 months old, not 2, on 1 Mar 2004.<\/p>\n

So, there are two uncertainties, a vague age – “two months”, not “two months and 4 days” – and a vague date we asked the question, sometime in March. These two uncertainties combine to produce a range of possible birthdates, from earliest to latest. So the program produces two dates, an earliest possible birthdate, and a latest possible birthdate.<\/p>\n

All this is of more than academic interest. I researched my family tree some while back, and was forever adding up ages and dates. I wrote a not-very-good spreadsheet to help. This web tool is intended to replace my spreadsheet, to be a more precise and general tool, and to be useful to others.<\/p>\n

Much more on this later! Meanwhile, try out the tool at http:\/\/www.eversholt.org.uk\/birthdate<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

The birthdate tool works out when someone might have been born, given their age. That doesn’t sound very hard, but turns out to be very tricky. If you find a bug, please leave a post here telling me what dates have gone wrong, and I’ll be very grateful. Sometime in in March 2004, I saw […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[3],"tags":[],"class_list":["post-10","post","type-post","status-publish","format-standard","hentry","category-birthdate"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/posts\/10","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/comments?post=10"}],"version-history":[{"count":3,"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/posts\/10\/revisions"}],"predecessor-version":[{"id":13,"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/posts\/10\/revisions\/13"}],"wp:attachment":[{"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/media?parent=10"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/categories?post=10"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.eversholt.org.uk\/blog\/wp-json\/wp\/v2\/tags?post=10"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}