centration, the concentrations are usually analysed on the logarithmic scale. In other words, it is assumed that the log-transformed data are normally distributed. Lindsey et al. (2000a) argue that this may not be reasonable and suggest that the raw concentrations might be modelled using a distribution from a particular family of skewed distributions that include the gamma and Weibull. They further suggested that the disper-sion parameter of the c [ hosen distribution be modelle ] d by the function k − −k = ′ ′ − ke ) where t is time, V and k correspond to V , k , respectively, and δ is an additional parameter. Lindsey et al. (2000a) also showed how censored data can be included in the model. Censoring usually occurs when the later concentrations of drug in the blood cannot be measured because they fall below some limit of detection in the measuring device. (Censoring can also occur if samples fall above some upper limit of detection.) A common practice for dealing with censored data is to replace the missing value with a fixed value, such as half the limit of detection. Lindsey et al. (2000a) give an example of the analysis of some PK data and show that the gamma distribution allowing for censoring is a better fit than using the lognormal distribution and replacing the censored data with a fixed value. An interesting feature of the example considered by Lindsey et al. (2000a) is that the concentration of a metabolite was also measured on each subject. Lindsey et al. (2000b) show how the drug and its metabolite can be simultaneously modelled. Further analyses of this example are described in Lindsey et al. (1999), Lindsey and Jones (2000) and Lindsey et al. (2001).

DOI link for centration, the concentrations are usually analysed on the logarithmic scale. In other words, it is assumed that the log-transformed data are normally distributed. Lindsey et al. (2000a) argue that this may not be reasonable and suggest that the raw concentrations might be modelled using a distribution from a particular family of skewed distributions that include the gamma and Weibull. They further suggested that the disper-sion parameter of the c [ hosen distribution be modelle ] d by the function k − −k = ′ ′ − ke ) where t is time, V and k correspond to V , k , respectively, and δ is an additional parameter. Lindsey et al. (2000a) also showed how censored data can be included in the model. Censoring usually occurs when the later concentrations of drug in the blood cannot be measured because they fall below some limit of detection in the measuring device. (Censoring can also occur if samples fall above some upper limit of detection.) A common practice for dealing with censored data is to replace the missing value with a fixed value, such as half the limit of detection. Lindsey et al. (2000a) give an example of the analysis of some PK data and show that the gamma distribution allowing for censoring is a better fit than using the lognormal distribution and replacing the censored data with a fixed value. An interesting feature of the example considered by Lindsey et al. (2000a) is that the concentration of a metabolite was also measured on each subject. Lindsey et al. (2000b) show how the drug and its metabolite can be simultaneously modelled. Further analyses of this example are described in Lindsey et al. (1999), Lindsey and Jones (2000) and Lindsey et al. (2001).

centration, the concentrations are usually analysed on the logarithmic scale. In other words, it is assumed that the log-transformed data are normally distributed. Lindsey et al. (2000a) argue that this may not be reasonable and suggest that the raw concentrations might be modelled using a distribution from a particular family of skewed distributions that include the gamma and Weibull. They further suggested that the disper-sion parameter of the c [ hosen distribution be modelle ] d by the function k − −k = ′ ′ − ke ) where t is time, V and k correspond to V , k , respectively, and δ is an additional parameter. Lindsey et al. (2000a) also showed how censored data can be included in the model. Censoring usually occurs when the later concentrations of drug in the blood cannot be measured because they fall below some limit of detection in the measuring device. (Censoring can also occur if samples fall above some upper limit of detection.) A common practice for dealing with censored data is to replace the missing value with a fixed value, such as half the limit of detection. Lindsey et al. (2000a) give an example of the analysis of some PK data and show that the gamma distribution allowing for censoring is a better fit than using the lognormal distribution and replacing the censored data with a fixed value. An interesting feature of the example considered by Lindsey et al. (2000a) is that the concentration of a metabolite was also measured on each subject. Lindsey et al. (2000b) show how the drug and its metabolite can be simultaneously modelled. Further analyses of this example are described in Lindsey et al. (1999), Lindsey and Jones (2000) and Lindsey et al. (2001).