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Fortino Vela Peón Noé Becerra Rodríguez

Mayo, 2011

3er Encuentro de Usuarios de Stata en México

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p Yi=Y \ X[ ] =

exp!!i !

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•! Si "2 = 1 equidispersión.

•! Si "2 > 1 se tiene sobredispersión (muy común).

•! Si "2 < 1 infradispersión (poco común).

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!! Solo se estima

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!! Es necesario considerar modelos alternativos.

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!! Otra es (Cameron y Trivedi, 1986):

( ) ( ) )exp(1\ 2 !" iii XXyV +=

02>!para algún a ser estimado.

! (A)

( ) ( ) )exp()exp(1\ 2 !!" iiii XXXyV +=

para algún #2 > 0.

! (B)

1;CA$@A$@;G8C$

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