Um estudo do teste não paramétrico de Kohli aplicado em Conjoint Analysis / A study of nonparametric test of Kohli applied in Conjoint Analysis

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

05/08/2011

RESUMO

We conducted a consumers preference study with simulated data in order to compare Kohli’s (1988) nonparametric test, called h test, for assessing attributes significance in Conjoint Analysis (CA), with the usual ANOVA F test. We simulated preference rates given by 48 consumers to eight treatments formed by a full factorial combination scheme of 3 attributes (A, B and C) with two levels each. Our main goal was to try to understand the theoretical basis for the h test. Thus, we considered an additive CA model with no interaction and defined four scenarios with distinct Relative Importances (RI) for the attributes (and consequently for the range of the part-worths, PW): Scenario 1 – RIA = 60%, RIB = 30% and RIC = 10%; Scenario 2 – RIA = 40%, RIB = 40% and RIC = 20%; Scenario 3 – RIA = 35%, RIB = 35% and RIC = 30% and Scenario 4 – RIA = 5%, RIB = 45% and RIC = 50%. For each scenario we also generated the random error values of the CA model from two distinct probability distribution models, both with zero mean and with standard deviation equal to sigma (σ): the normal distribution and a non-normal U shaped distribution. In addition, for each distribution we also investigated the following sigma values (σ = 1,5; 2,0; 2,5; 3,0; 3,5 and 4.0). Results did not allow us to relate significance of an attribute by Kohli’s h test neither to (i) magnitude of the RI value, nor to (ii) range of PW’s in comparison to the σ value. Even under non normal data the h test did not give understandable results (in a practical sense). We concluded that the h test should not be recommended.

ASSUNTO(S)

estatísticas teste não paramétrico kohli conjoint analysis ciencias agrarias statistics nonparametric test kohli conjoint analysis

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