Mahmoud
★    

Jordan,
2015-03-03 21:04
(3340 d 18:33 ago)

Posting: # 14538
Views: 6,104
 

 sequence effect; CVintra>CVinter [General Sta­tis­tics]

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Dear Sir

  1. What about if P-value Subject(Sequence)>0.05 in ANOVA and
  2. CVintra > CVinter

Edit: Category and subject line changed. [Helmut]
 
Helmut
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Vienna, Austria,
2015-03-03 21:18
(3340 d 18:18 ago)

@ Mahmoud
Posting: # 14539
Views: 5,100
 

 sequence effect; CVintra>CVinter

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Hi Mahmoud,

❝ Dear Sir


This is not a boys-only club!

❝ 1. What about if P-value Subject(Sequence)>0.05 in ANOVA

  1. Testing for a sequence- (aka unequal carry-over-) effect is futile! Some people are worried about a sig­ni­ficant one (p<0.05); I’m not one of them. Since you cannot do anything meaningful, forget it. You can only avoid it by design, i.e., by a sufficiently long washout period. Search the forum. We have discussed that many, many times. You will find some useful references as well.

❝ 2. CVintra > CVinter


2. Happens sometimes. I have seen that particularly with PPIs.

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Mahmoud
★    

Jordan,
2015-03-03 22:45
(3340 d 16:51 ago)

@ Helmut
Posting: # 14540
Views: 5,080
 

 sequence effect; CVintra>CVinter

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Dear Dr

What did you mean

❝ This is not a boys-only club

not good words for me

I ask you about if the P-value for the random effect Subject(Sequence) in the ANOVA > .05 which means that MSinter=MSintra

2. if CVintra > CVinter we need to find REML estimator for MSintra

to find the C.I for PK
 
Helmut
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Vienna, Austria,
2015-03-04 01:24
(3340 d 14:12 ago)

@ Mahmoud
Posting: # 14541
Views: 5,050
 

 consider an all-fixed effects model

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Hi Mahmoud,

❝ Dear Dr

❝ What did you mean

❝ ❝ This is not a boys-only club

❝ not good words for me


Well, I meant that a top level post should be addressed the entire group of forum members – not to the “Sirs” only. Might be offensive to our female members. BTW, I’m not a Dr…

❝ I ask you about if the P-value for the random effect Subject(Sequence) in the ANOVA > .05 which means that MSinter=MSintra


A nonsignificant p-value does no imply that MSinter=MSinter. Not sure what you mean here.

❝ 2. if CVintra > CVinter we need to find REML estimator for MSintra

❝

❝ to find the C.I for PK


Is this a software issue? In a mixed-effects model (SAS Proc MIXED or the default BE setup in Phoenix / Win­Nonlin) sometimes rarely you may run into convergence issues (i.e., a negative esti­mate of the subject(sequence) term). Which software did you use – and which code? Consider switching to an all-fixed effect model (SAS Proc GLM without the RANDOM term; in PHX/WNL delete Random 1 sub­ject(sequence) and add it to the fixed effects). Note that with such a setup you cannot estimate CVinter any more. However, it is not necessary for BE (which is estimated from the residual error). CVinter is only “nice to know”.

See also these threads: #10139, #12289.
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