WWWusage                 package:ts                 R Documentation

_I_n_t_e_r_n_e_t _U_s_a_g_e _p_e_r _M_i_n_u_t_e

_D_e_s_c_r_i_p_t_i_o_n:

     A time series of the numbers of users connected to the Internet
     through a server every minute.

_U_s_a_g_e:

     data(WWWusage)

_F_o_r_m_a_t:

     A time series of length 100.

_S_o_u_r_c_e:

     Durbin, J. and Koopman, S. J. (2001) Time Series Analysis by State
     Space Methods.  Oxford University Press. <URL:
     http://www.ssfpack.com/dkbook/>

_R_e_f_e_r_e_n_c_e_s:

     Makridakis, S., Wheelwright, S. C. and Hyndman, R. J. (1998)
     Forecasting: Methods and Applications. Wiley.

_E_x_a_m_p_l_e_s:

     data(WWWusage)
     work <- diff(WWWusage)
     par(mfrow = c(2,1)); plot(WWWusage); plot(work)

     aics <- matrix(, 6, 6, dimnames=list(p=0:5, q=0:5))
     for(q in 1:5) aics[1, 1+q] <- arima(WWWusage, c(0,1,q),
         optim.control = list(maxit = 500))$aic
     for(p in 1:5)
        for(q in 0:5) aics[1+p, 1+q] <- arima(WWWusage, c(p,1,q),
            optim.control = list(maxit = 500))$aic
     round(aics - min(aics, na.rm=TRUE), 2)

