Workshop Blogging V: Convergence

(Part 1, Part II, Part III, Part IV)
If I could work out how to get the photo I took last night off my phone, you could all see the monster nan we ate last night before the football.

Most of the rest of yesterday and today has been spent trying to get things working. I’ve been building habitat models that can be used to estimate where butterflies are living. These will (in one way or another) be part of a bigger model, which incorporates the observation process, i.e. we will separate out true absences (i.e. when a butterfly isn’t there) from when it just isn’t seen.
Yesterday I got a model working based on observations of presences of the species. This wasn’t too bad, until I tried adding a spatial component. At that point the computer gave up and just stared at me. I’ll try Plan B (a CAR model) next week.
This morning I have been developing a similar model for abundance data. The model sort-of works (i.e. fitting it to the data produces numbers), but the numbers are rubbish. Basically, I am simulating the parameters (using MCMC, for those who know), and getting different answers depending on where I start it from. I know the problem (a lot of random effects), but have never understood the different possible solutions well enough to see what to do. This is a bit embarrassing, as people seem to think I know what I’m doing with this stuff.
Ho hum. This part of the workshop finishes this evening, so I can write a promissory note to say I’ll sort it out later.

About rpg

Scientist, poet, gadfly
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7 Responses to Workshop Blogging V: Convergence

  1. Maxine Clarke says:

    This is turning into an endurance test. Well done for keeping up the blogging experiment. Are you going to do this for every conference and workshop you attend, from now on?

  2. Bob O'Hara says:

    Oh, I doubt it.
    I’ll hve to think about what exactly these sorts of post are meant to show. Hopefully someone else will be enthused to do a better job than I have.
    I’m wondering if I can escape to have crepes and lemonade for lunch.

  3. Maxine Clarke says:

    Hope you made it! (for a bit of C&L I mean)

  4. Bob O'Hara says:

    I tried, but couldn’t find it, so I went to a book shop instead. And failed to find any books worth buying.

  5. Graham Steel says:

    And failed to find any books worth buying.
    Oh well, here’s some music for you Bob.
    On the butterfly front, I recorded/produced a song called Butterfly.

    The guitar is a tad piercing but overall, not bad for an analog 4 track jobby.

  6. Maxine Clarke says:

    Oh, pity. It is a moveable feast stall with an awning, I think they have their name on it (Jackson). It is in that little square where the fire eaters and people hang out, near a toyshop. Next time….

  7. Bob O'Hara says:

    Ah, I think everyone had packed up because the weather wasn’t promising. Or they had been warned…
    Graham – thanks for the song! The Beast enjoyed it, the guitar solo especially.

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