retinal

The study recorded the decay of intraocular gas $C_3F_8$ in complex retinal surgeries 
following initial injection in an ophthalmology study, reported in Meyers <em>et al.</em> (1992). The outcome
variable was the percent of gas left in the eye. The gas, with three different concentration levels, 15%, 
20% and 25% was injected into the eye before surgery for 31 patients. They were then followed three to eight
(average of five) times over a three-month period, and the volume of gas in the eye at the follow-up times
were recorded as a percentage of the initial gas volume. The primary interest was to investigate whether 
concentration levels of the gas injected in patients' eyes affect the decay rate of the gas. 


Simplex density, distribution, quantile functions as well as random variable
generation of the simplex distribution are given. Regression analysis of proportional data
using various kinds of simplex models is available. In addition, GEE method can be applied
to longitudinal data to model the correlation. Residual analysis is also involved. Some
subroutines are written in C with GNU Scientific Library (GSL) so as to facilitate the
computation.

Peng Zhang

simplexreg

Regression Analysis of Proportional Data Using Simplex
Distribution

retinal function

A data frame with 181 observations on the following 6 variables. 
   	<dl> </dl> 

retinal: Data on recorded decay of intraocular gas in complex retinal surgeries

Description

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References