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  GenStat  ~  degrees of freedom in AMMI AOVTable

MarcinP
Posted: Mon Apr 30, 2018 11:53 am Reply with quote
Joined: 03 Apr 2017 Posts: 6
Dear All,

I've run AMMI procedure using the following code

ammi[PRINT=aovtable,genotype,environment,estimates,stability; NROOTS=2;PLOT=ipca,mean;scaling=symmetric]\
yield; GENOTYPES=variety; ENVIRONMENTS=env;replicates= rep

More or less I know how the degrees of freedom are calculated in case when I run AMMI procedure for means. Does anyone know how the degrees of freedom are calculated in the above case? I'm especially interested how the degrees of freedom for replicates within environments are calculated.

I would be grateful for any suggestions or clues.

Best regards
Marcin
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Marie Smith
Posted: Thu May 03, 2018 7:11 am Reply with quote
Guest
Dear Marcin


The d.f. for AMMI in the procedure are calculated as follows, and thus for the example in the procedure of 4 genotypes and 4 environments with two roots (output attached) are:
for IPCA1 = number of genotypes + number of environments - 3 - (2*(1-1)) = 4+4-3 = 5
for IPCA2 = number of genotypes + number of environments - 3 - (2*(2-1)) = 4+4-3-2 = 3

etc.
There is a paper by Forkman & Piepho that Hugh Gauch refers to of calculating the IPCA d.f. and he has included in his new free version on AMMISOFT, that calculates the d.f. differently.


Regards
Marie Smith




On 30 April 2018 at 13:53, MarcinP <forum777@vsni.co.uk (forum777@vsni.co.uk)> wrote:
Quote:
Dear All,

I've run AMMI procedure using the following code

ammi[PRINT=aovtable,genotype,environment,estimates,stability; NROOTS=2;PLOT=ipca,mean;scaling=symmetric]\
yield; GENOTYPES=variety; ENVIRONMENTS=env;replicates= rep

More or less I know how the degrees of freedom are calculated in case when I run AMMI procedure for means. Does anyone know how the degrees of freedom are calculated in the above case? I'm especially interested how the degrees of freedom for replicates within environments are calculated.

I would be grateful for any suggestions or clues.

Best regards
Marcin









--
Vriendelike groete/Kind regards


Marie F. Smith (Pr.Sci.Nat.) M.Sc.stats4science
Biostatistician
Tel: +27 12 997 0653

Cell: 083 306 2753

Post generated using Mail2Forum (http://www.mail2forum.com)



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Marie Smith
Posted: Thu Jun 07, 2018 7:21 am Reply with quote
Guest
Dear Marcin


I have been reading your request again and notice that you actually are most interested in how the reps within environments d.f. are calculated:
Example 4 Gen x 4 Env x 2 Rep: Blocks df = 4(2-1) = 4
Example 7 Gen x 10 Env x 4 Rep: Blocks df = 10(4-1) = 30


Regards, Marie




On 3 May 2018 at 09:09, Marie Smith <marie.smith@stats4science.com (marie.smith@stats4science.com)> wrote:
Quote:
Dear Marcin


The d.f. for AMMI in the procedure are calculated as follows, and thus for the example in the procedure of 4 genotypes and 4 environments with two roots (output attached) are:
for IPCA1 = number of genotypes + number of environments - 3 - (2*(1-1)) = 4+4-3 = 5
for IPCA2 = number of genotypes + number of environments - 3 - (2*(2-1)) = 4+4-3-2 = 3

etc.
There is a paper by Forkman & Piepho that Hugh Gauch refers to of calculating the IPCA d.f. and he has included in his new free version on AMMISOFT, that calculates the d.f. differently.


Regards
Marie Smith




On 30 April 2018 at 13:53, MarcinP <forum777@vsni.co.uk (forum777@vsni.co.uk)> wrote:
Quote:
Dear All,

I've run AMMI procedure using the following code

ammi[PRINT=aovtable,genotype,environment,estimates,stability; NROOTS=2;PLOT=ipca,mean;scaling=symmetric]\
yield; GENOTYPES=variety; ENVIRONMENTS=env;replicates= rep

More or less I know how the degrees of freedom are calculated in case when I run AMMI procedure for means. Does anyone know how the degrees of freedom are calculated in the above case? I'm especially interested how the degrees of freedom for replicates within environments are calculated.

I would be grateful for any suggestions or clues.

Best regards
Marcin











--
Vriendelike groete/Kind regards


Marie F. Smith (Pr.Sci.Nat.) M.Sc.stats4science
Biostatistician
Tel: +27 12 997 0653

Cell: 083 306 2753












--
Vriendelike groete/Kind regards


Marie F. Smith (Pr.Sci.Nat.) M.Sc.stats4science
Biostatistician
Tel: +27 12 997 0653

Cell: 083 306 2753










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