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)

     ## S3 method for class 'reliability':
     print(x, digits=4, ...)

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

       S: the covariance matrix of the items; normally, there should be
          at least 3 items and certainly no fewer than 2.

       x: reliability object to be printed.

  digits: number of decimal places.

     ...: not used: for compatibility with the print generic."

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

     an object of class reliability, which normally would be printed.

_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))

