Evaluation of the behavior of thrips in several ground covers by regression models

Angela Maria Marcone de Araujo, Josmar Mazucheli, Carlos Alberto Scapim, Fernando Alves de Albuquerque, Marcelo Vivas



 Using the number of thrips found in the maize seedlings from a longitudinal study, in this work a regression analysis was conducted through polynomial models and nonlinear logistic, under the assumption of homoscedasticity and multiplicative heteroscedasticity of variances. The response variable represents the number of thrips in adult phase observed in an entirely randomized trial involving 4 ground cover systems (tumbled oat, desiccated oat, mowed oat and incorporated oat), 8 replications with portions of 57.6 m2 and evaluated at 7, 11, 16, 23 and 31 days after the seedlings emergence. The parameters from the adopted models (homoscedastic and heteroscedastic) were estimated by maximizing the logarithm of the verisimilitude function. The adjusted model, via maximum verisimilitude, under the assumption of heteroscedasticity of the variances, did not over estimate the true asymptotic average number of thrips.



ground cover; nonlinear regression; heteroscedastic errors.

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DOI: http://dx.doi.org/10.4025/actascitechnol.v40i1.31008

ISSN 1806-2563 (impresso) e ISSN 1807-8664 (on-line) e-mail: actatech@uem.br


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