beav1                  package:MASS                  R Documentation

_B_o_d_y _T_e_m_p_e_r_a_t_u_r_e _S_e_r_i_e_s _o_f _B_e_a_v_e_r _1

_D_e_s_c_r_i_p_t_i_o_n:

     Reynolds (1994) describes a small part of a study of the long-term
     temperature dynamics of beaver _Castor canadensis_ in
     north-central Wisconsin.  Body temperature was measured by
     telemetry every 10 minutes for four females, but data from a one
     period of less than a day for each of two animals is used there.

_U_s_a_g_e:

     data(beav1)

_F_o_r_m_a_t:

     The 'beav1' data frame has 114 rows and 4 columns. This data frame
     contains the following columns:

     '_d_a_y' Day of observation (in days since the beginning of 1990),
          December 12-13.

     '_t_i_m_e' Time of observation, in the form '0330' for 3.30am

     '_t_e_m_p' Measured body temperature in degrees Celcius

     '_a_c_t_i_v' Indicator of activity outside the retreat

_N_o_t_e:

     The observation at 22:20 is missing.

_S_o_u_r_c_e:

     P. S. Reynolds (1994) Time-series analyses of beaver body
     temperatures. Chapter 11 of Lange, N., Ryan, L., Billard, L.,
     Brillinger, D., Conquest, L. and Greenhouse, J. eds (1994) _Case
     Studies in Biometry._ New York: John Wiley and Sons.

_R_e_f_e_r_e_n_c_e_s:

     Venables, W. N. and Ripley, B. D. (2002) _Modern Applied
     Statistics with S._ Fourth edition.  Springer.

_S_e_e _A_l_s_o:

     'beav2'

_E_x_a_m_p_l_e_s:

     attach(beav1)
     beav1$hours <- 24*(day-346) + trunc(time/100) + (time%%100)/60
     plot(beav1$hours, beav1$temp, type="l", xlab="time",
        ylab="temperature", main="Beaver 1")
     usr <- par("usr"); usr[3:4] <- c(-0.2, 8); par(usr=usr)
     lines(beav1$hours, beav1$activ, type="s", lty=2)
     temp <- ts(c(beav1$temp[1:82], NA, beav1$temp[83:114]), start=9.5, frequency=6)
     activ <- ts(c(beav1$activ[1:82], NA, beav1$activ[83:114]), start=9.5, frequency=6)

     acf(temp[1:53])
     acf(temp[1:53], type = "partial")
     ar(temp[1:53])
     act <- c(rep(0, 10), activ)
     X <- cbind(1, act = act[11:125], act1 = act[10:124],
               act2 = act[9:123], act3 = act[8:122])
     alpha <- 0.80
     stemp <- as.vector(temp - alpha*lag(temp, -1))
     sX <- X[-1, ] - alpha * X[-115,]
     beav1.ls <- lm(stemp ~ -1 + sX, na.action = na.omit)
     summary(beav1.ls, cor = FALSE)
     detach("beav1"); rm(temp, activ)

