

Nelson(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 acceler-
     ated tests, published in IEEE Transactions on Reliabil-
     ity.  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_:

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

