What is it about?
By using a large data base and modelling the two populations being logarithms of "high ACTH levels" and logarithms of "low ACTH levels" according to a mixture of a two component normal distributions a robust estimation procedure known as L2 minimum distance estimation is employed. Thresholds dividing the two populations of high-ACTH and low-ACTH horses were then established at different levels of sensitivity and specificity and compared with clinical subgroups of horses divided based on reported clinical signs, as having high (n = 4036) or low (n = 3022) clinical suspicion of PPID.
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Why is it important?
It is important since this is the first study extracting the information from the aforesaid UK data base that does not assume the data are from PPID and non PPID horses based on a subjective assessment. The information about the component distributions is extracted without identifying each horse according to whether or not it has PPID.
Perspectives
The method of estimation of mixture parameters using the L2 minimum distance procedure is known to be robust, since the method of estimation is equivalent to M-estimation with a bounded and smooth psi-function. This means that the method of estimation is weakly continuous and Fr'echet differentiable, qualities which are defining robust methods of estimation.
Dr Brenton R. Clarke
Murdoch University
Read the Original
This page is a summary of: Clinically and temporally specific diagnostic thresholds for plasma ACTH in the horse, Equine Veterinary Journal, June 2020, Wiley,
DOI: 10.1111/evj.13292.
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