Pingouinche ☆ France, 2009-08-19 13:39 (5731 d 23:20 ago) (edited on 2009-08-19 16:21) Posting: # 4061 Views: 10,708 |
|
Hello, I'm new at BA/BE studies and I don't understand very well how to analyze a crossover experiment with R or SAS. I'm trying to replicate the results I've read in a book (Design and analysis of bioavailability and bioequivalence studies): a complete example is proposed in section 3.6, data is p.73 and the classic ANOVA table I want to obtain is p.78. I would like to know how I can obtain such an ANOVA table with R or SAS, with inter- and intra- source of variations separated. I don't manage to write properly the model, in order to make SAS or R understand that each subject has two measures, and that some factors have to be tested between subject, and others within subjects. Do you a have a document, or a code "ready to use" which could help me to replicate the results of the book ? Thanks ! Edit: Subject line changed. [Helmut] |
Pingouinche ☆ France, 2009-08-19 18:21 (5731 d 18:39 ago) @ Pingouinche Posting: # 4064 Views: 8,362 |
|
❝ Edit: Subject line changed. [Helmut] Yes, sorry ![]() More precisely : with the (R) command anova.table=lm(Result ~ Sequence + Subject:Sequence + Period + Drug, data=crossover) I get this table : Analysis of Variance Table This new ANOVA table has approximately the same structure as the table in the book, but it is not the good syntax/answer... Does someone have an idea? ![]() |
Helmut ★★★ ![]() ![]() Vienna, Austria, 2009-08-19 19:05 (5731 d 17:55 ago) @ Pingouinche Posting: # 4065 Views: 8,533 |
|
Dear Pingouinche, sorry, but I'm short in time (sometimes I have to work). ![]() You don’t have to reinvent the wheel! Chow and Liu’s book gives SAS-code for a 2×2×2 design in the annex. Another one is given in Patterson's/Jones' book. For S-Plus code see this post (Pikounis); needs some (a few) modifications for There’s the wonderful bioequivalence package bear for — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![]() Helmut Schütz ![]() The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
Pingouinche ☆ France, 2009-08-20 00:20 (5731 d 12:39 ago) @ Helmut Posting: # 4067 Views: 8,350 |
|
❝ sorry, but I’m short in time (sometimes I have to work). Yes, I can understand you have to work (just a little ![]() ❝ You don’t have to reinvent the wheel! ❝ Chow and Liu’s book gives SAS-code for a 2×2×2 design in the annex. Indeed, there is probably the SAS-code on the book, but... Unfortunately, I don't have the book and the code is not included in the extracts available on Google Books... Precisely, I'd like to know their code, because whatever I do, I don't manage to obtain the same ANOVA table as them ! |
Helmut ★★★ ![]() ![]() Vienna, Austria, 2009-08-20 03:12 (5731 d 09:47 ago) @ Pingouinche Posting: # 4068 Views: 8,327 |
|
![]() ❝ Indeed, there is probably the SAS-code on the book, ^^^^^^ The probability is close to 1 (unless you buy a misprint or somebody has ripped these pages out). ❝ Unfortunately, I don't have the book and the code is not included in the extracts available on Google Books... No? Would you mind looking at page 560? OK, the interesting ones are 561-562. ![]() ❝ Precisely, I'd like to know their code, because whatever I do, I don't manage to obtain the same ANOVA table as them ! In your first post you said you read the book. Fine. But f…g Google Books is not a source to gain knowlege from - at least nobody can ‘read a book’ there. The third edition was published this year. If you are with a company which can’t afford a book and give you enough time to study it, change the company. Quickly! If you are a poor fellow, maybe you can get the second edition cheaper or even a used copy. If you are a student, go to your library. Or get a copy of pages 559-576 (2nd ed, 691-714 3rd ed.) from a remote reference provider. It’s even possible to get their ANOVA-table up and running in M$-Excel (see the screenshot in this post). Or search this forum (codes for both SAS and Sorry for the harsh reply, but please do you homework first. ![]() See also this post for something you may check. — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![]() Helmut Schütz ![]() The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
Pingouinche ☆ France, 2009-08-20 11:19 (5731 d 01:41 ago) @ Helmut Posting: # 4073 Views: 8,281 |
|
❝ If you are a student, go to your library. Indeed, I am. Mathematician. Doing a short work experience in PK/PD for the summer. But the poor library of my little university: 1) is closed, 2) doesn't have any book an BA/BE anyway. ![]() I know Google Books is not the best way to learn BA/BE tests, but for me, it's simply the only way. I'll find something... Thanks. |
yjlee168 ★★★ ![]() ![]() Kaohsiung, Taiwan, 2009-08-19 20:42 (5731 d 16:17 ago) @ Pingouinche Posting: # 4066 Views: 8,382 |
|
Dear Pingouinche, ❝ [..] Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 ❝ This new ANOVA table has approximately the same structure as the table in the book, but it is not the good syntax/answer... ![]() — All the best, -- Yung-jin Lee bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee Kaohsiung, Taiwan https://www.pkpd168.com/bear Download link (updated) -> here |
Helmut ★★★ ![]() ![]() Vienna, Austria, 2009-08-20 03:19 (5731 d 09:41 ago) @ yjlee168 Posting: # 4069 Views: 8,538 |
|
Hi Yung-jin! ❝ […] The above ANOVA table is quite self-explained. Yes, but have you noticed that results for period and treatment are numerically identical? Maybe there’s a mistake in the coding of the dataset (levels?). — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![]() Helmut Schütz ![]() The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
yjlee168 ★★★ ![]() ![]() Kaohsiung, Taiwan, 2009-08-20 14:02 (5730 d 22:58 ago) @ Helmut Posting: # 4075 Views: 8,303 |
|
Dear Helmut, ❝ Yes, but have you noticed that results for period and treatment are numerically identical? You're right! I really did NOT notice that part. A typical anova output obtained from bear is shown as follows. Dependent Variable: lnAUC0t ❝ Maybe there’s a mistake in the coding of the dataset (levels?). The period and drug (treatment) could be coded incorrectly in the dataset. — All the best, -- Yung-jin Lee bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee Kaohsiung, Taiwan https://www.pkpd168.com/bear Download link (updated) -> here |
yjlee168 ★★★ ![]() ![]() Kaohsiung, Taiwan, 2009-08-20 14:17 (5730 d 22:43 ago) @ Pingouinche Posting: # 4076 Views: 8,313 |
|
Dear Pingouinche, Could you show us your dataset? Just part of it will be enough. ❝ Response: Result ❝ Df Sum Sq Mean Sq F value Pr(>F) ❝ Sequence 1 555.7 555.7 4.4106 0.0474 * ❝ Periode 1 0.9 0.9 0.0074 0.9324 ❝ [...] Periode? Did you edit the output when you're posting it or was it from the original output? Thanks. — All the best, -- Yung-jin Lee bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee Kaohsiung, Taiwan https://www.pkpd168.com/bear Download link (updated) -> here |