[R-sig-eco] T50 or ED50 for count data

[Mehdi Abedi]

Dear Colleagues,

I am interested to calculate time to 50 percentage for count data.
I am working on soil seed bank germination. I have recorded number of
seedling emergence in 10 different times for species. The total number of
seeds in soil is not known therefore it is not proportional data but we can
argue that after this period all viable seeds already germinated(total
seedling emergence).

I am familiar with drc package for calculation T50 but only for
proportional data like germination in petridishes which total number of
seed in each pteridishes is known  T50 could be calculated.

Could we calculate T50 for count data as well? because we have total
seedling emergence in the end, therefore their distribution during time is
important and having this index we can find when species germinate ...
This indices could be useful for other count data specially survival
studies.

warm regards
Mehdi


*Mehdi Abedi Department of Range Management*

*Faculty of Natural Resources & Marine Sciences *

*Tarbiat Modares University (TMU) *

*46417-76489, Noor*

*Mazandaran, IRAN *

*mehdi.abedi at modares.ac.ir <Mehdi.abedi at modares.ac.ir>*

*Homepage
<http://www.modares.ac.ir/en/Schools/nat/Academic_Staff/~mehdi.abedi>*

*Tel: +98-122-6253101 *

*Fax: +98-122-6253499*

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