Comparison of three alternative methods for analysis of equine Faecal Egg Count Reduction Test data
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Comparison of three alternative methods for analysis of equine Faecal Egg Count Reduction Test data. / Denwood, M.J.; Reid, S.W.J.; Love, S.; Nielsen, Martin Krarup; Matthews, L.; McKendrick, I.J.; Innocent, G.T.
I: Preventive Veterinary Medicine, Bind 93, Nr. 4, 01.03.2010, s. 316-323.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Comparison of three alternative methods for analysis of equine Faecal Egg Count Reduction Test data
AU - Denwood, M.J.
AU - Reid, S.W.J.
AU - Love, S.
AU - Nielsen, Martin Krarup
AU - Matthews, L.
AU - McKendrick, I.J.
AU - Innocent, G.T.
PY - 2010/3/1
Y1 - 2010/3/1
N2 - The Faecal Egg Count Reduction Test (FECRT) is the most widely used method of assessing the efficacy of anthelmintics, and is the only in vivo technique currently approved for use with horses. Equine Faecal Egg Count (FEC) data are frequently characterised by a low mean, high variability, small sample size and frequent zero count observations. Accurate analysis of the data therefore depends on the use of an appropriate statistical technique. Analyses of simulated FECRT data by methods based on calculation of the empirical mean and variance, non-parametric bootstrapping, and Markov chain Monte Carlo (MCMC) are compared. The MCMC method consistently outperformed the other methods, independently of the distribution from which the data were generated. Bootstrapping produced notional 95% confidence intervals containing the true parameter as little as 40% of the time with sample sizes of less than 50. Analysis of equine FECRT data yielded inconclusive results in 53 of 63 (84%) datasets, suggesting that the routine use of prior sample size calculations should be adopted to ensure sufficient data are collected. The authors conclude that computationally intensive parametric methods such as MCMC be used for analysis of FECRT data with sample sizes of less than 50, in order to avoid erroneous inference about the true efficacy of anthelmintics in the field.
AB - The Faecal Egg Count Reduction Test (FECRT) is the most widely used method of assessing the efficacy of anthelmintics, and is the only in vivo technique currently approved for use with horses. Equine Faecal Egg Count (FEC) data are frequently characterised by a low mean, high variability, small sample size and frequent zero count observations. Accurate analysis of the data therefore depends on the use of an appropriate statistical technique. Analyses of simulated FECRT data by methods based on calculation of the empirical mean and variance, non-parametric bootstrapping, and Markov chain Monte Carlo (MCMC) are compared. The MCMC method consistently outperformed the other methods, independently of the distribution from which the data were generated. Bootstrapping produced notional 95% confidence intervals containing the true parameter as little as 40% of the time with sample sizes of less than 50. Analysis of equine FECRT data yielded inconclusive results in 53 of 63 (84%) datasets, suggesting that the routine use of prior sample size calculations should be adopted to ensure sufficient data are collected. The authors conclude that computationally intensive parametric methods such as MCMC be used for analysis of FECRT data with sample sizes of less than 50, in order to avoid erroneous inference about the true efficacy of anthelmintics in the field.
KW - Animals
KW - Anthelmintics
KW - Feces
KW - Helminthiasis, Animal
KW - Horse Diseases
KW - Horses
KW - Netherlands
KW - Parasite Egg Count
U2 - 10.1016/j.prevetmed.2009.11.009
DO - 10.1016/j.prevetmed.2009.11.009
M3 - Journal article
C2 - 19962203
VL - 93
SP - 316
EP - 323
JO - Preventive Veterinary Medicine
JF - Preventive Veterinary Medicine
SN - 0167-5877
IS - 4
ER -
ID: 17520179