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Ancestor Number Predictor

Discussion in 'Advanced techniques for experienced users' started by AndyMick, Nov 18, 2013.

  1. AndyMick

    AndyMick LostCousins Star

    Back in July, before the computer gremlins attacked, I created a rough computer model of how many ancestors you might expect to find given what you know about them already. This was prompted by some discussion on the forum of how many ancestors we had located. Tim's recent comment persuaded me to make it public in its current state even though the gremlins might not let me handle the feedback - we'll see!

    The model is not very good, but gives an idea of where research needs to be concentrated. For example, I have considerably fewer folks in 1911 than the model suggests I should have.

    I wrote it originally in VBA (in Excel) but I converted it to Javascript to run self contained in a web page - and consequently people with the requisite computer skills can look at it and see how rotten my code is - I mean can see how it could be improved:)

    Talking of Alexander reminds me, the model is for England and Wales, although I don't think it would take much to adapt for the US - sorry Scots and Canadians, but you only have the one census on the system, so it's not my fault!

    So, this is the link you've all been waiting for! (Lights blue touch paper and stands back!)
     
    AndyMick, Nov 18, 2013
    #1
  2. Alexander Bisset

    Alexander Bisset Administrator Staff Member

    I'll go have a look. As you say it's a pain only having one Scottish census to enter.
     
    Alexander Bisset, Nov 18, 2013
    #2
  3. AndyMick

    AndyMick LostCousins Star

    I've been having a play with the numbers - I got the best match of 1841/1881 numbers with a start date of 1770 and 3 children. But that made my 1911 even worse :(
     
    AndyMick, Nov 18, 2013
    #3
  4. Alexander Bisset

    Alexander Bisset Administrator Staff Member

    Can you clarify what you mean by made 1911 even worse. Do you mean it suggested you had loads of people you should have but dont?
     
    Alexander Bisset, Nov 18, 2013
    #4
  5. Bryman

    Bryman LostCousins Megastar

    It certainly looks that way to me.
     
    Bryman, Nov 18, 2013
    #5
  6. AndyMick

    AndyMick LostCousins Star

    And me!

    And what really galls me is that I was unable to take advantage of the Ancestry 1911 census offering. B****y computers!
     
    AndyMick, Nov 19, 2013
    #6
  7. Alexander Bisset

    Alexander Bisset Administrator Staff Member

    The problem I see with the model is in the go back to come forward aspect. When you are "matching" your 1841 & 1881 stats you aren't really comparing apples with apples, more like comparing apples with washing machines.

    The problem is that you really don't know and there are no constraints in the model to say whether your 1841 and 1881 stats are actually right. ie: there is nothing I can see in the model that actually uses the 1841 & 1881 stats as an input to work out how many ancestors you should have. So you can't then match your 1841 & 1881 stats to see what 1911 should be as you have no idea if 1841 and 1881 are right and small variants in the numbers say add an extra 1841 family of 6 and suddenly the whole numbering is out.

    It's interesting approach but I fear there are too many variables. What should be possible on the other hand is to say you have X people alive on the 1841 census with an average age of A so you'd expect Y in 1881 and Z in 1911 given the numbers of children and life expectancy.

    That way you fix one point in the jigsaw. A point that can be a known quantity. Then you can extrapolate from that known point.
     
    Alexander Bisset, Nov 19, 2013
    #7
  8. Tim

    Tim Megastar and Moderator Staff Member

    Predicting is all fine but will never work because of the variables. Assuming 2 every generation is ok, but if the 2nd generation in only has 1 then the calculation is out all the way through.

    To me it makes more sense to compare your figures on LC with each other

    1841 251
    1881 557
    1911 769

    1881 is about 2 times 1841
    1911 is about 3 times 1841
     
    Tim, Nov 19, 2013
    #8
  9. Alexander Bisset

    Alexander Bisset Administrator Staff Member

    However it does have merit in dealing with expected values. Yes it won't get it 100% right not least of which is that if you find a sibling to a 3g or 4g grandfather/mother to take Andy's example the all of a sudden you have potentially doubled all the numbers for that branch.
     
    Alexander Bisset, Nov 20, 2013
    #9

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