[R-sig-ME] binary response, random factor

[Boris Fuchs]

-----BEGIN PGP SIGNED MESSAGE-----

Hash: SHA1

 

  Can you please send this to r-sig-mixed-models at r-project.org ?

 

  I think the answer would be of general interest.

 

  I do have one paper (Pasch et al Am Nat 2013 in which we initially
considered using a mixed model but decided not to in the end -- you could
cite that in support ...

 

On 15-03-05 11:05 AM, Boris Fuchs wrote:

> Hi Ben

> 

> 

> 

> Thirst: thanks for all the answers you share in the net.

> 

> 

> 

> Guess you are busy. I try to be short.

> 

> 

> 

> I try to publish my master thesis:

> 

> 

> 

> I have a data set of 106 Scandinavian wolves. A binary response 

> whether they are tested positive or negative for a parasite (Sarcoptic 

> mange). I test if individual variables (sex, age…) or environmental 

> variables (fox density, latitude…) are better explaining the test 

> results (positive or negative).

> 

> 

> 

> I use glm’s, selected by AICc in R.

> 

> 

> 

> 

> 

> 16 are positive.

> 

> 

> 

> I am aware of potential overfitting problems (max K = n/10 or better 

> 20…)

> 

> 

> 

> About 40 individuals got sampled >1 up to 4 times. –> random factor

> 

> 

> 

> Some territories are sampled multiple times. à random factor

> 

> 

> 

> However:

> 

> I did not succeed with building random structures and I belief because 

> of missing variability within the random factors. Most of the 

> individuals are tested only once. Easier if most of them would be 

> tested several times and would be both, positive and negative.

> The same with the territories. Is this right?

> 

> 

> 

> I would like to state the lacking variation as a reason to not use a 

> random structure. But I need some published support (not to say it 

> works anyway, but not). I seem not skilled enough to understand

> (select) the key literature. Do you have any hint?

> 

> 

> 

> 

> 

> Since most of the individuals are sampled once and the time between 

> the sampling is by far enough to change from positive to negative and 

> vica versa I think I can take the risk of violation of independence.

> 

> 

> 

> 

> 

> 

> 

> Boris

> 

> 

> 

> 

> 

> 

> 

> boris fuchs ole evenstadsvei 1156 2480 koppang +47 41 51 49 30 

> boris.fuchs at schultraining.ch

> 

> 

> 

> 

 

-----BEGIN PGP SIGNATURE-----

Version: GnuPG v1.4.11 (GNU/Linux)

 

iQEcBAEBAgAGBQJU+L7dAAoJEOCV5YRblxUH1IUH/jciVrXp/i5o6B8w6rM68LEy

CMHD3udnNLr+DFBXKVjH+XM6pljGDQSBUKBYncSZgY0jTWDsMfHTDgt0mHttlodF

koAebeqminRsvp3yc+lgpE4stBAEVUPRIh2onaVS6pzISYaoZEmmGwrJNAerZvyl

sEUgTH+pLSsSdXDJzKR8KYgocoAifMvHoDmwjtkdIz6FTdGxpqgkHNjLHj5Itesd

mexuWPyFFcmHI1IuCUNiuZnJNvA07c1isWSncuY0+NkfsRZWjjTNi8PNSuClLDXx

9K0k+8HySbH9zNqyFod9ErDd566AVeSVgqItA0xEtNVE6puyvFGF1tT1gw5WPes=

=15/3

-----END PGP SIGNATURE-----

 

 

boris fuchs
ole evenstadsvei 1156
2480 koppang
+47 41 51 49 30
boris.fuchs at schultraining.ch

 


	[[alternative HTML version deleted]]