# PharmPK Discussion - Intra-subject variation calculation

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• On 6 Mar 2007 at 10:41:40, "Wichittra Tassaneeyakul" (wichitt.at.kku.ac.th) sent the message
`The following message was posted to: PharmPKDear All,If we conduct the BE study using 2 way crossoverdesign and from ANOVAresults some say that we could calculate the intra-subject variation.Could you please tell me thw way to calculate it which MS errorshould weuse (from Sub(seq)???).  Another point is how to calculate the 90%Confidence interval from Geometric mean, can we use Excel software?ThanksWichittra--Dr. Wichittra TassaneeyakulDepartment of PharmacologyFaculty of MedicineKhon Kaen UniversityKhon Kaen 40002Thailand`
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• On 6 Mar 2007 at 12:47:52, "Nand Kishore Rawat" (Nand.KishoreRawat.-at-.ranbaxy.com) sent the message
`The following message was posted to: PharmPKDear Wichittra,while calculating ANOVA for two-way cross over design,PK ParametersCmax,AUC's are calculated usingmixed effect ANOVA model using Type III sum of squares and taking into consideration different factorsresponsible for variation. These factors are tested at differentlevel of significance depending uponlevarge of factors.Intra Subject variability is nothing but it is considered as residualvariability after accounting for variabiltybetween treatment,period and subject and it is a major determinant tocalculate estimated sample size.for calculating 90% CI following procedure is adopted90% confidence interval for the ratio of the test and referenceproduct averages (least square means) arecalculated using the 90% confidence interval for the differences inthe averages (arithmetic means) of thelog-transformed data and then taking the antilog of the obtainedconfidence limitswe can use Excel for calculating 90% CI, But performing ANOVA inExcel,does not provide more detailed summaryoutputs as compared to SAS and other statistical softwares.Best Regards,Nand Kishore RawatBio-Statistician (CPP)Ranbaxy Research LaboratoriesGurgaon-122001 India`
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• On 6 Mar 2007 at 05:19:27, Bang.Qian.Xu.aaa.watson.com sent the message
`To calculate intra-subject variation  you can use the formula below:100*sqrt(exp(MSE)-1)   Bang Qian Xu`
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• On 6 Mar 2007 at 08:59:53, "Peter Bonate" (peter.bonate.-a-.gmail.com) sent the message
`Which error term to use depends on which SAS proc you use.  If youuse GLM then use subject nested within sequence as the error term.If you use the Mixed procedure, you use the true error term from themodel.The geometric mean can be calculated as first taking tha natural logof the data then calculating the arithmetic mean of the natural logtransformed data.  The arithmetic mean is then exponentiated.  Thisis the geometric mean.Good luck,pete bonate`
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• On 6 Mar 2007 at 20:07:04, helmut.schuetz.-at-.bebac.at sent the message
`The following message was posted to: PharmPKDear Wichittra!You wrote: >If we conduct the BE study using 2 way crossoverdesign and from ANOVA >results some say that we could calculate the intra-subject variation. >Could you please tell me thw way to calculate it which MS error >should we use (from Sub(seq)???). >Yes.CV-intra = sqrt(exp(MSE)-1) >Another point is how to calculate the 90% >Confidence interval from Geometric mean, can we use Excel software? >Funny, we had this today ;-)Have a look at this thread:http://forum.bebac.at/mix_entry.php?id=559Good look,Helmut--Helmut SchuetzBEBACConsultancy Services for Bioequivalence and Bioavailability StudiesNeubaugasse 36/111070 Vienna/Austriatel/fax +43 1 2311746Web http://BEBAC.atBE/BA Forum http://forum.bebac.at`
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• On 7 Mar 2007 at 13:11:47, "Nand Kishore Rawat" (Nand.KishoreRawat.aaa.ranbaxy.com) sent the message
`The following message was posted to: PharmPK   Dear All,   we are conducting Bio-equivalence study on Parallel design. Cansomeone Pls let me know   the formula to Calculate InterCV in Parallel design using SASSoftware.   Best Regards,   Nand Kishore Rawat   Bio-Statistician (CPP)   Ranbaxy Research Laboratories   Gurgaon-122001 India`
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• On 12 Mar 2007 at 12:12:23, HDesai.aaa.wockhardtin.com sent the message
`Dear Wichittra,You wrote: >If we conduct the BE study using 2 way crossoverdesign and from ANOVA >results some say that we could calculate the intra-subject variation. >Could you please tell me thw way to calculate it which MS error >should we use (from Sub(seq)???).My Reply:MS error from Sub(seq)is used to calculate inter subject variation.To calculate intra-subject variation, MS error obtained from entireANOVAmodel is used.Best Regards,harshada`
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