Log in
Register|
ioanam ★ Romania, 2008-12-20 13:57 (5985 d 08:53 ago) Posting: # 2958 Views: 24,134 |
|
|
Hallo, I need to understand better the differences between the terms: – CV% derived from calculation of mean and standard deviation of PK parameters – Intra and inter subject variability - derived from ANOVA analysis. Those two formulas provided in Canadian bioequivalence guidance can be applied using KINETICA software? And is right when I calculate number of subjects using data about intra – subject variability, isn't it? Thank you. Have a nice day, Jo |
|
sinhmar ☆ India, 2008-12-23 08:04 (5982 d 14:46 ago) @ ioanam Posting: # 2961 Views: 22,240 |
|
|
❝ I need to understand better the differences between the terms: ❝ – CV% derived from calculation of mean and standard deviation of PK parameters ❝ – Intra and inter subject variability - derived from ANOVA analysis. CV (coefficient of variation) is a constant used to define variability, based on standard deviation, in data without considering any effect. It is a statistical measure of dispersion of data points in data series around mean. In crossover bioequivalence studies, ANOVA table divides the total variability into variability due to different effects like subject, sequence, period and treatment and residual variability is an undefined variability accounted to within subject variability and other nuisance effects. The intra-subject variability (within subject variability) reflects the residual variability after accounting for differences between subjects, periods, sequence and formulations. And inter subject variability is a between subject variability calculated by taking out the residual effect (inter subject) from subject (Sequence) effect, as it is clear from the following formula: Inter-subject CV = 100 x (MSSubject (Seq) - MSResidual/2)0.5 ❝ Those two formulas provided in Canadian bioequivalence guidance can be applied using KINETICA software? i don't have any idea about Kinetica... but we can calculate intra/inter CV in SPSS and SAS ❝ And is right when I calculate number of subjects using data about intra – subject variability, isn't it? yes, we need intra CV for calculating number of subjects but for that we need ratio(T/R) of means also  Edit: Standard quotes restored. [Helmut] |
|
Helmut ★★★   Vienna, Austria, 2008-12-23 14:28 (5982 d 08:22 ago) @ sinhmar Posting: # 2962 Views: 22,016 |
|
|
Dear Shinmar & Jo! ❝ CV (coefficient of variation) is a constant used to define variability, based on standard deviation, in data without considering any effect. Not a constant, but an estimate.  Therefore one should consider its uncertainty (dependent on the sample size) if applying the number in further study planning. ❝ [...] as it is clear from the following formula: ❝ Inter-subject CV = 100 x (MSSubject (Seq) - MSResidual/2)0.5 Nice, but your formula is valid only for untransformed data (additive model). For formulas of the multiplicative model (log-transformed data) of most PK metrics see this post. — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png) Helmut Schütz ![[image]](https://static.bebac.at/img/CC by.png) The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
|
Mohamed Yehia ★ Egypt, 2017-07-22 14:06 (2849 d 09:44 ago) @ ioanam Posting: # 17592 Views: 14,873 |
|
|
Dear All, Can anyone tell me how to write the sas syntax to calculate the CV intra and inter subject variability for 2x2 crossover bioequivalence study??. Many Thanks. Edit: Subject line changed and full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post #5! [Helmut] |
Ing. Helmut Schütz