Resumen

SEGURA-CORREA, José C  y  SOLORIO-RIVERA, José L. Intra-cluster correlation coefficients and design effects for seropositivity to brucelosis, viral bovine diarrhea and infectious bovine rhinotracheitis in milk farms. INCI [online]. 2006, vol.31, n.12, pp.885-887. ISSN 0378-1844.

Estimates of the intra-cluster correlation coefficients (ICC) or of the design effect (D) for infectious diseases could be of interest in the design of surveys and for the calculation of variance inflation factors for the estimators of prevalence in cluster samplings. The ICC and D for brucellosis, bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) were calculated using the Bennett method and analysis of variance (VARCOMP). The ICC values for brucellosis, BVD and IBR using such methods were 0.162 and 0.153, 0.044 and 0.015 and 0.110 and 0.128, while for D the values were 3.33 and 3.09, 1.63 and 1.21, and 2.58 and 3.02, respectively. In conclusion, the ICC and D values for brucellosis, BVD and IBR were different, according to the method used and for each of the infections; therefore, large sample sizes are required in order to obtain the same precision in the estimates of prevalences. The report of the ICC and D values will be of great help in the planning and design of epidemiological studies.

Palabras clave : Brucelosis ; Coeficiente de Correlación dentro de Hato ; Diarrea Viral Bovina ; Efecto de Diseño ; Rinotraqueitis Infecciosa Bovina .