_C_o_n_t_r_a_s_t _M_a_t_r_i_c_e_s
	
	     contr.helmert(n, contrasts=TRUE)
	     contr.poly(n, contrasts=TRUE)
	     contr.sum(n, contrasts=TRUE)
	     contr.treatment(n, contrasts=TRUE)
	
	_V_a_l_u_e:
	
	     A matrix with n rows and k columns, with k=n-1 if con-
	     trasts is TRUE and k=n if contrasts is FALSE.
	
	     These functions are used for creating contrast matrices
	     for use in fitting analysis of variance and regression
	     models.  The columns of the resulting matrices contain
	     contrasts which can be used for coding a factor with n
	     levels.  The returned value contains the computed con-
	     trasts.  If the argument contrasts is FALSE then an
	     additional column of ones is prepended to the matrix.
	
	_S_e_e _A_l_s_o:
	
	     contrasts, glm, lm.