reliability              package:Rcmdr              R Documentation

_R_e_l_i_a_b_i_l_i_t_y _o_f _a _C_o_m_p_o_s_i_t_e _S_c_a_l_e

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

     Calculates Cronbach's alpha and standardized alpha (lower bounds
     on reliability) for a composite (summated-rating) scale.
     Standardized alpha is for the sum of the standardized items. In
     addition, the function calculates alpha and standardized alpha for
     the scale with each item deleted in turn, and computes the
     correlation between each item and the sum of the other items.

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

     reliability(S)

_A_r_g_u_m_e_n_t_s:

       S: the covariance matrix of the items

_V_a_l_u_e:

     The function does not return a useful value; it is called for its
     side effect - to print the results.

_A_u_t_h_o_r(_s):

     John Fox jfox@mcmaster.ca

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

     N. Cliff (1986) Psychological testing theory. Pp. 343-349 in S.
     Kotz and N. Johnson, eds., _Encyclopedia of Statistical Sciences,
     Vol. 7_. Wiley.

_S_e_e _A_l_s_o:

     'cov'

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

     data(DavisThin)
     reliability(cov(DavisThin))

