Sample size considerations for livestock movement network data.
The movement of animals between farms contributes to infectious disease spread in production animal populations, and is increasingly investigated with social network analysis methods. Tangible outcomes of this work include the identification of high-risk premises for targeting surveillance or control programs. However, knowledge of the effect of sampling or incomplete network enumeration on these studies is limited. In this study, a simulation algorithm is presented that provides an estimate of required sampling proportions based on predicted network size, density and degree value distribution. The algorithm may be applied a priori to ensure network analyses based on sampled or incomplete data provide population estimates of known precision. Results demonstrate that, for network degree measures, sample size requirements vary with sampling method. The repeatability of the algorithm output under constant network and sampling criteria was found to be consistent for networks with at least 1000 nodes (in this case, farms). Where simulated networks can be constructed to closely mimic the true network in a target population, this algorithm provides a straightforward approach to determining sample size under a given sampling procedure for a network measure of interest. It can be used to tailor study designs of known precision, for investigating specific livestock movement networks and their impact on disease dissemination within populations.
The Mackinnon Project, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, 250 Princes Highway, Werribee, VIC 3030, Australia. Electronic address: caitlin.pfeiffer@unimelb.edu.au.
Caitlin N
CN
Pfeiffer
Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.
Simon M
SM
Firestone
The Mackinnon Project, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, 250 Princes Highway, Werribee, VIC 3030, Australia.
Angus J D
AJ
Campbell
The Mackinnon Project, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, 250 Princes Highway, Werribee, VIC 3030, Australia.
John W A
JW
Larsen
Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.
Mark A
MA
Stevenson
D000465:Algorithms; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D003198:Computer Simulation; D058751:Livestock; D018401:Sample Size; D012680:Sensitivity and Specificity; D014186:Transportation
Social network analysis; degree; network; risk-based disease control; sample size