Nelson                package:NISTnls                R Documentation

_D_i_a_l_e_c_t_r_i_c _b_r_e_a_k_d_o_w_n _d_a_t_a

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

     The `Nelson' data frame has 128 rows and 3 columns of data from an
     accelerated test of dialectric breakdown.

_A_r_g_u_m_e_n_t_s:

       y: A numeric vector of dialectric breakdown strength values. 

      x1: A numeric vector of time values. 

      x2: A numeric vector of temperature values. 

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

     This data frame contains the following columns:

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

     These data are the result of a study involving the analysis of
     performance degradation data from accelerated tests, published in
     IEEE Transactions on Reliability.  The response variable is
     dialectric breakdown strength in kilo-volts, and the predictor
     variables are time in weeks and temperature in degrees Celsius.

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

     Nelson, W. (1981).   Analysis of Performance-Degradation Data.  
     IEEE Transactions on Reliability. Vol. 2, R-30, No. 2, pp.
     149-155.

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

     data(Nelson)
     plot(y ~ x1, data = Nelson, log = "y")
     plot(y ~ x2, data = Nelson, log = "y")
     coplot(y ~ x1 | x2, data = Nelson)
     coplot(y ~ x2 | x1, data = Nelson)

     fm1 <- nls(log(y) ~ b1 - b2*x1 * exp(-b3*x2), data = Nelson,
                start = c(b1 = 2, b2 = 0.0001, b3 = -0.01), trace = TRUE)

     fm2 <- nls(log(y) ~ b1 - b2*x1 * exp(-b3*x2), data = Nelson,
                start = c(b1 = 2.5, b2 = 0.000000005, b3 = -0.05), trace = TRUE)

     fm3 <- nls(log(y) ~ cbind(1, -x1 * exp(-b3*x2)), data = Nelson,
                start = c(b3 = -0.01), trace = TRUE, algorithm = "plinear")

     fm4 <- nls(log(y) ~ cbind(1, -x1 * exp(-b3*x2)), data = Nelson,
                start = c(b3 = -0.05), trace = TRUE, algorithm = "plinear")

