Age calculations are wrong in the data dump export

Question

I'm still 29, and this shows correctly on StackOverflow and the rest of the "trilogy" because I entered my correct birth date. The data dump says I'm 30. I know this is happening to other users as well — you can see it here:
StackQL test site updated to March data http://jcoehoorn.dyndns.org/stackql/default.aspx?qid=470

Answer 1

This will be fixed in the next dump.

Answer 2

Maybe Jeff should post a question on StackOverflow asking how to calculate someone's age from their birthday and the current date...

Oh look, he did ask that in 2008.

Perhaps he now believes his current knowledge will be entirely obsolete in one year, not five, so he deliberately wipes his memory every 12 months to make room.

Answer 3

Here are the results of twenty randomly chosen users:

User 218540: 28 years in data dump, 27 years on website
User 160208: 25 years in data dump, 24 years on website
User 23897: 40 years in data dump, 39 years on website
User 86038: 23 years in data dump, 22 years on website
User 20367: 39 years in data dump, 38 years on website
User 106040: 31 years in data dump, 31 years on website
User 2368: 27 years in data dump, 27 years on website
User 116553: 23 years in data dump, 22 years on website
User 191385: 15 years in data dump, 14 years on website
User 214528: 24 years in data dump, 23 years on website
User 18102: 35 years in data dump, 35 years on website
User 58309: 42 years in data dump, 42 years on website
User 110227: 32 years in data dump, 32 years on website
User 98585: 26 years in data dump, 25 years on website
User 184340: 39 years in data dump, 38 years on website
User 250022: 24 years in data dump, 23 years on website
User 8843: 39 years in data dump, 39 years on website
User 234438: 33 years in data dump, 32 years on website
User 5975: 27 years in data dump, 26 years on website
User 251474: 34 years in data dump, 33 years on website

14 out of 20 differ, and where they do, the age on the website is exactly one less than the age in the db.

Code used:

import sqlite3, random, httplib2, re

# the <center> cannot hold it is too late
age_re = re.compile(r"<td>age</td>\s*<td>\s*(\d*)\s*</td>")
http = httplib2.Http()
db = sqlite3.connect("so201003.db")

with_age = db.execute("SELECT Id, Age FROM USERS WHERE Age IS NOT NULL").fetchall()
random.shuffle(with_age)

sample = with_age[:20]

for userid, db_age in sample:
    url = "http://stackoverflow.com/users/%d" % userid
    response, content = http.request(url, headers = {"User-Agent": "Hi Jeff! Joel says you're wrong. I'm checking that."})
    if response.status != 200:
        raise IOError("Response was %d" % response.status)
    web_age = int(age_re.search(content).groups(1)[0])
    print "User %d: %d years in data dump, %d years on website" % (userid, db_age, web_age)

Answer 4

I expect they are doing the simple year calculation. If you were born in 1970, and it's 2010, then sometime during this year you have already or will turn 40. It's easier/cheaper than a full date calculation, and does it really matter?

It could also be to avoid minor privacy concerns - look at previous data dumps and determine the birthmonth. Seems a bit over concerned, though, so it's unlikely, but possible. Notably one can determine the exact birthdate by reading the user page once a day and waiting for the age to change, so it's already visible, but takes up to a year to find out.