phi2poly                package:psych                R Documentation

_C_o_n_v_e_r_t _a _p_h_i _c_o_e_f_f_i_c_i_e_n_t _t_o _a _p_o_l_y_c_h_o_r_i_c _c_o_r_r_e_l_a_t_i_o_n

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

     Given a phi coefficient (a Pearson r calculated on two dichotomous
     variables), and the marginal frequencies (in percentages), what is
     the corresponding estimate of the polychoric correlation?

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

     phi2poly(ph, cp, cc)

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

      ph: phi 

      cp: probability of the predictor - the so called selection ratio 

      cc: probability of the criterion - the so called success rate. 

_D_e_t_a_i_l_s:

     Uses John Fox's polycor package, which in turn requires the
     mvtnorm package

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

     a polychoric correlation

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

     William Revelle

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

     'polychor.matrix'

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

     #phi2poly(.3,.5,.5)
     #phi2poly(.3,.3,.7)

