Thurber               package:NISTnls               R Documentation

_E_l_e_c_t_r_o_n _m_o_b_i_l_i_t_y _d_a_t_a

_D_e_s_c_r_i_p_t_i_o_n:

     The 'Thurber' data frame has 37 rows and 2 columns.

_F_o_r_m_a_t:

     This data frame contains the following columns:

     _y A numeric vector of electron mobility values.

     _x A numeric vector of logs of electron density values.


_D_e_t_a_i_l_s:

     These data are the result of a NIST study involving semiconductor
     electron mobility.  The response  variable is a measure of
     electron mobility, and the  predictor variable is the natural log
     of the density.

_S_o_u_r_c_e:

     Thurber, R., NIST (197?).   Semiconductor electron mobility
     modeling.

_E_x_a_m_p_l_e_s:

     Try <- function(expr) if (!inherits(val <- try(expr), "try-error")) val
     plot(y ~ x, data = Thurber)
     Try(fm1 <- nls(y ~ (b1+x*(b2+x*(b3+b4*x))) / (1+x*(b5+x*(b6+x*b7))),
                data = Thurber, trace = TRUE,
                start = c(b1 = 1000, b2 = 1000, b3 = 400, b4 = 40,
                          b5 = 0.7, b6 = 0.3, b7 = 0.03)))
     Try(fm1a <- nls(y ~ (b1+x*(b2+x*(b3+b4*x))) / (1+x*(b5+x*(b6+x*b7))),
                data = Thurber, trace = TRUE, alg = "port", 
                start = c(b1 = 1000, b2 = 1000, b3 = 400, b4 = 40,
                          b5 = 0.7, b6 = 0.3, b7 = 0.03)))
     Try(fm2 <- nls(y ~ (b1+x*(b2+x*(b3+b4*x))) / (1+x*(b5+x*(b6+x*b7))),
                data = Thurber, trace = TRUE,
                start = c(b1 = 1300, b2 = 1500, b3 = 500, b4 = 75,
                          b5 = 1, b6 = 0.4, b7 = 0.05)))
     Try(fm2a <- nls(y ~ (b1+x*(b2+x*(b3+b4*x))) / (1+x*(b5+x*(b6+x*b7))),
                data = Thurber, trace = TRUE, alg = "port", 
                start = c(b1 = 1300, b2 = 1500, b3 = 500, b4 = 75,
                          b5 = 1, b6 = 0.4, b7 = 0.05)))
     Try(fm3 <- nls(y ~ outer(x, 0:3, "^")/(1+x*(b5+x*(b6+x*b7))),
                data = Thurber, trace = TRUE,
                start = c(b5 = 0.7, b6 = 0.3, b7 = 0.03), alg = "plinear"))
     Try(fm4 <- nls(y ~ outer(x, 0:3, "^")/(1+x*(b5+x*(b6+x*b7))),
                data = Thurber, trace = TRUE,
                start = c(b5 = 1, b6 = 0.4, b7 = 0.05), alg = "plinear"))

