## Calculation of intra-subject CVs in replicate design [General Statistics]

Hi Andrew,

It's a bit late for this reply, but I found the answer to your question. You don't need to run proc GLM. The replicate SAS output gives all of the information you need to calculate intra- and inter-CV, where it outputs the covariate matrix ("Covariate Parameter Estimates"). The SAS output might look like this:

Covariate Parameter Estimates

Cov Parm Subject Group Estimate

FA(1,1) Subject 0.5928 <---- (sig_BT, the between-subject standard deviation for the Test product)

FA(2,1) Subject 0.4968 <---- (sig_BR, the between-subject standard deviation for the Reference product)

FA(2,2) Subject 2E-17 <---- (sig_D, the subject-by-formulation interaction term)

Residual Subject Treatment A 0.124 <---- (sig_WT^2, the within-subject standard deviation for the Test product)

Residual Subject Treatment B 0.242 <---- (sig_WR^2, the within-subject standard deviation for the Reference product)

The intra-subject variabilities are still calculated from the residuals as in a 2-way crossover, using:

IntraCV_T = 100%*sqrt(exp(sig_WT^2)-1) (in this case, = 100*sqrt(exp(0.124)-1) = 36.3%

IntraCV_R = 100%*sqrt(exp(sig_WR^2)-1) (in this case, = 100*sqrt(exp(0.242)-1) = 52.3%

FA(1,1) and FA(2,1) are the inter-subject standard deviations for Test and Reference products, respectively:

InterCV_T = 100%*sqrt(exp(sig_BT^2)-1) = 100*sqrt(exp(0.5928^2)-1) = 64.9%

IntraCV_R = 100%*sqrt(exp(sig_BR^2)-1) = 100*sqrt(exp(0.4968^2)-1) = 52.9%

Hope this helps,

Dave

It's a bit late for this reply, but I found the answer to your question. You don't need to run proc GLM. The replicate SAS output gives all of the information you need to calculate intra- and inter-CV, where it outputs the covariate matrix ("Covariate Parameter Estimates"). The SAS output might look like this:

Covariate Parameter Estimates

Cov Parm Subject Group Estimate

FA(1,1) Subject 0.5928 <---- (sig_BT, the between-subject standard deviation for the Test product)

FA(2,1) Subject 0.4968 <---- (sig_BR, the between-subject standard deviation for the Reference product)

FA(2,2) Subject 2E-17 <---- (sig_D, the subject-by-formulation interaction term)

Residual Subject Treatment A 0.124 <---- (sig_WT^2, the within-subject standard deviation for the Test product)

Residual Subject Treatment B 0.242 <---- (sig_WR^2, the within-subject standard deviation for the Reference product)

The intra-subject variabilities are still calculated from the residuals as in a 2-way crossover, using:

IntraCV_T = 100%*sqrt(exp(sig_WT^2)-1) (in this case, = 100*sqrt(exp(0.124)-1) = 36.3%

IntraCV_R = 100%*sqrt(exp(sig_WR^2)-1) (in this case, = 100*sqrt(exp(0.242)-1) = 52.3%

FA(1,1) and FA(2,1) are the inter-subject standard deviations for Test and Reference products, respectively:

InterCV_T = 100%*sqrt(exp(sig_BT^2)-1) = 100*sqrt(exp(0.5928^2)-1) = 64.9%

IntraCV_R = 100%*sqrt(exp(sig_BR^2)-1) = 100*sqrt(exp(0.4968^2)-1) = 52.9%

Hope this helps,

Dave

—

David Dubins, Ph.D., B.A.Sc.

Associate Professor, Teaching Stream

Director, Pharmaceutical Chemistry Specialist Program

Leslie Dan Faculty of Pharmacy

University of Toronto

144 College Street (room PB802), Toronto, ON M5S 3M2

Tel. +1 416-946-5303; FAX: +1 416 978-8511

David Dubins, Ph.D., B.A.Sc.

Associate Professor, Teaching Stream

Director, Pharmaceutical Chemistry Specialist Program

Leslie Dan Faculty of Pharmacy

University of Toronto

144 College Street (room PB802), Toronto, ON M5S 3M2

Tel. +1 416-946-5303; FAX: +1 416 978-8511

### Complete thread:

- Calculation of intra-subject CVs in replicate design Dr Andrew Leary 2007-11-20 14:50 [General Statistics]
- Calculation of intra-subject CVs in replicate design Helmut 2007-11-20 16:27
- Calculation of intra-subject CVs in replicate design Dr Andrew Leary 2007-11-20 16:46

- Calculation of intra-subject CVs in replicate design Dr Andrew Leary 2007-12-05 16:35
- Calculation of intra-subject CVs in replicate designddubins 2008-03-01 19:28
- Data set? Helmut 2008-03-02 13:01
- Calculation of intra-subject CVs in replicate design d_labes 2008-03-03 12:05
- Calculation of intra-subject CVs in replicate design Sathya 2008-09-20 08:17
- G matrix in SAS Proc Mixed d_labes 2008-09-22 11:35
- Wordplay :-) Helmut 2008-09-22 11:47
- G matrix in SAS Proc Mixed Sathya 2008-09-24 11:02
- G matrix in SAS Proc Mixed d_labes 2008-09-24 12:46
- G matrix in SAS Proc Mixed Sathya 2008-09-25 06:02

- G matrix in SAS Proc Mixed d_labes 2008-09-24 12:46

- G matrix in SAS Proc Mixed d_labes 2008-09-22 11:35

- Calculation of intra-subject CVs in replicate design Sathya 2008-09-20 08:17

- Calculation of intra-subject CVs in replicate designddubins 2008-03-01 19:28

- Calculation of intra-subject CVs in replicate design Helmut 2007-11-20 16:27