hald                   package:wle                   R Documentation

_H_a_l_d _D_a_t_a

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

     Montgomery and Peck (1982) illustrated variable selection
     techniques on the Hald cement data and gave several references to
     other analysis. The response variable _y_ is the _heat evolved_ in
     a cement mix. The four explanatory variables are ingredients of
     the mix, i.e., x1: _tricalcium aluminate_, x2: _tricalcium
     silicate_, x3: _tetracalcium alumino ferrite_, x4: _dicalcium
     silicate_. An important feature of these data is that the
     variables x1 and x3 are highly correlated (corr(x1,x3)=-0.824), as
     well as the variables x2 and x4 (with corr(x2,x4)=-0.975). Thus we
     should expect any subset of (x1,x2,x3,x4) that includes one
     variable from highly correlated pair to do as any subset that also
     includes the other member.

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

     data(hald)

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

     'hald' is a matrix with 13 observations (rows) and 5 variables
     (columns), the first column is the dependent variable. 'y.hald'
     and 'x.hald' are also availables.

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

     Montgomery, D.C., Peck, E.A. (1982)  _Introduction to linear
     regression analysis,_ John Wiley, New York.

