growthcurve             package:statmod             R Documentation

_C_o_m_p_a_r_e _G_r_o_u_p_s _o_f _G_r_o_w_t_h _C_u_r_v_e_s

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

     Do all pairwise comparisons between groups of growth curves using
     a permutation test.

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

     compareGrowthCurves(group,y,levels=NULL,nsim=100,fun=meanT,times=NULL,verbose=TRUE,adjust="holm")
     compareTwoGrowthCurves(group,y,nsim=100,fun=meanT)

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

   group: vector or factor indicating group membership.  Missing values
          are allowed in 'compareGrowthCurves' but not in
          'compareTwoGrowthCurves'.

       y: matrix of response values with rows for individuals and
          columns for times.  The number of rows must agree with the
          length of 'group'. Missing values are allowed.

  levels: a character vector containing the identifiers of the groups
          to be compared.  By default all groups with two more more
          members will be compared.

    nsim: number of permutations to estimated p-values.

     fun: the statistic used to measure the distance between two groups
          of growth curves. Default to a mean t-statistic.

   times: a numeric vector containing the column numbers on which the
          groups should be compared. By default all the columns are
          used.

 verbose: should progress results be printed?

  adjust: method used to adjust for multiple testing, see 'p.adjust'.

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

     'compareTwoGrowthCurves' performs a permutation test of the
     difference between two groups of growth curves.
     'compareGrowthCurves' does all pairwise comparisons between two or
     more groups of growth curves. Accurate p-values can be obtained by
     setting 'nsim' to some large value, 'nsim=10000' say.

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

     'compareTwoGrowthCurves' returns a list with two components,
     'stat' and 'p.value', containing the observed statistics and the
     estimated p-value.  'compareGrowthCurves' returns a data frame
     with components 

  Group1: name of first group in a comparison

  Group2: name of second group in a comparison

    Stat: observed value of the statistic

 P.Value: estimated p-value

adj.P.Value: p-value adjusted for multiple testing

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

     Gordon Smyth

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

     'compareGrowthCurves', 'compareTwoGrowthCurves'

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

     # A example with only one time
     data(PlantGrowth)
     compareGrowthCurves(PlantGrowth$group,as.matrix(PlantGrowth$weight))
     # Can make p-values more accurate by nsim=10000

