rotarod            package:exactRankTests            R Documentation

_R_o_t_a_t_i_n_g _R_a_t_s _D_a_t_a

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

     The endurance time of 24 rats in two groups in a rotating
     cylinder.

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

     data(rotarod)

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

     A data frame with 24 observations on the following 2 variables.

     _t_i_m_e the endurance time

     _g_r_o_u_p a factor with levels 'control' and 'treatment'. .in -5 

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

     The 24 rats received a fixed oral dose of a centrally acting
     muscle relaxant (treatment) or a saline solvent (control). They
     were placed on a rotating cylinder and the length of time each rat
     remains on the cylinder is measured, up to a maximum of 300
     seconds. The rats were randomly assigned to the control and
     treatment group.

     Note that the empirical variance in the control group is 0 and
     that the group medians are identical.

     This dataset serves as the basis of an comparision of the results
     of the  Wilcoxon-Mann-Whitney test computed by 11 statistical
     packages in Bergmann et al. (2000). The exact conditional p-value
     is $0.0373$ (two-sided) and $0.0186$ (one-sided). The asymptotic
     two-sided  p-value (corrected for ties) is reported as $0.0147$.

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

     Reinhard Bergmann, John Ludbrook & Will P.J.M. Spooren (2000),
     Different outcomes of the Wilcoxon-Mann-Whitney test from
     different  statistics packages. _The American Statistician_, 
     *54*(1), 72-77.

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

     data(rotarod)
     wilcox.exact(time ~ group, data=rotarod, alternative="g")
     wilcox.exact(time ~ group, data=rotarod, conf.int=TRUE)
     wilcox.exact(time ~ group, data=rotarod, exact=FALSE)
     # the permutation test
     perm.test(time ~ group, data=rotarod)
     perm.test(time ~ group, data=rotarod, exact=FALSE)

