bodyfat                 package:mfp                 R Documentation

_p_e_r_c_e_n_t_a_g_e _o_f _b_o_d_y _f_a_t _d_e_t_e_r_m_i_n_e_d _b_y _u_n_d_e_r_w_a_t_e_r _w_e_i_g_h_i_n_g

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

     A data frame containing the estimates of the percentage of body
     fat  determined by underwater weighing and various body
     circumference  measurements for 252 men.

     Source: Roger W. Johnson (1996), ''Fitting Percentage of Body Fat
     to  Simple Body Measurements'', Journal of Statistics Education. 
     Original data are from K. Penrose, A. Nelson, and A. Fisher
     (1985),  ''Generalized Body Composition Prediction Equation for
     Men Using  Simple Measurement Techniques'' (abstract), Medicine
     and Science in  Sports and Exercise, 17(2), 189. 

     Data were supplied by Dr. A. Garth Fisher, Human Performance
     Research  Center, Brigham Young University, who gave permission to
     freely distribute  the data and use them for non-commercial
     purposes.  Note, however, that there seem to be a few errors.  
     For instance, body densities for cases 48, 76, and 96 seem to have
     one digit  in error in the two body fat percentage values.   Also
     note a man (case 42) over 200 pounds in weight who is less than 3
     feet tall  (the height should presumably be 69.5 inches, not 29.5
     inches).   Percent body fat estimates are truncated to zero when
     negative (case 182).

_U_s_a_g_e:

     data(GBSG)

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

     This data frame contains the observations of 252 men:

     _c_a_s_e Case number.

     _b_r_o_z_e_k Percent body fat using Brozek's equation: 457/Density -
          414.2

     _s_i_r_i Percent body fat using Siri's equation: 495/Density - 450

     _d_e_n_s_i_t_y Density determined from underwater weighing (gm/cm^3).

     _a_g_e Age (years).

     _w_e_i_g_h_t Weight (lbs).

     _h_e_i_g_h_t Height (inches).

     _n_e_c_k Neck circumference (cm).

     _c_h_e_s_t Chest circumference (cm).

     _a_b_d_o_m_e_n Abdomen circumference (cm) ''at the umbilicus and level 
          with the iliac crest''.

     _h_i_p Hip circumference (cm).

     _t_h_i_g_h Thigh circumference (cm).

     _k_n_e_e Knee circumference (cm).

     _a_n_k_l_e Ankle circumference (cm).

     _b_i_c_e_p_s Biceps (extended) circumference (cm).

     _f_o_r_e_a_r_m Forearm circumference (cm).

     _w_r_i_s_t Wrist circumference (cm) ''distal to the styloid
          processes''.

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

     e.g. <URL: http://lib.stat.cmu.edu/datasets/bodyfat>

_R_e_f_e_r_e_n_c_e_s:

     R.W. Johnson (1996). Fitting percentage of body fat to simple body
     measurements. _Journal of Statistics Education [Online]_, *4(1)*.

     K.W. Penrose, A.G. Nelson, A.G. Fisher (1985). Generalized body
     composition prediction equation for men using simple measurement
     techniques. _Medicine and Science  in Sports and Exercise_, *17*,
     189.

     P. Royston, W. Sauerbrei (2004). Improving the robustness of
     fractional polynomial models  by preliminary covariate
     transformation. Submitted.

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

         data(bodyfat)
         bodyfat$height[bodyfat$case==42] <- 69.5   # apparent error
         bodyfat <- bodyfat[-which(bodyfat$case==39),]  # cp. Royston & Sauerbrei, 2004
         mfp(siri ~ fp(age, df = 4, select = 0.1) + fp(weight, df = 4, select = 0.1)
                      + fp(height, df = 4, select = 0.1), family = gaussian, data = bodyfat)

