[R] Ordinal regression with some categories combined for some data

[Bob O'Hara]

Hi!

I've been asked about a problem where I think I can see how to write
the model, but don't know if it's been implemented in R. It's not
something I work on a lot, so I'm hoping someone else can point me to
an answer straight away.

The researcher has been carrying out germination experiments: lost of
seeds are put in several conditions (temperature humidity etc.), and
every few days they are checked to see if they have germinated.
Because the days are discrete I think it makes sense to view this as
an ordinal regression problem (rather than as an interval censored
survival analysis). But what makes this tricky is that there are days
when the researcher only checked some seeds. So for some seeds the
germination might fall into more than one category.

Is there a package in R that can handle this, i.e. do an ordinal
regression where for some observations the categories are interval
censored? Or is it easier to go straight to a full interval-censored
survival analysis?

Bob

-- 
Bob O'Hara

Biodiversity and Climate Research Centre
Senckenberganlage 25
D-60325 Frankfurt am Main,
Germany

Tel: +49 69 798 40226
Mobile: +49 1515 888 5440
WWW:   http://www.bik-f.de/root/index.php?page_id=219
Blog: http://occamstypewriter.org/boboh/
Journal of Negative Results - EEB: www.jnr-eeb.org