growthcurve

0th

Percentile

Compare Groups of Growth Curves

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

Keywords
regression
Usage
compareGrowthCurves(group,y,levels=NULL,nsim=100,fun=meanT,times=NULL,verbose=TRUE,adjust="holm")
compareTwoGrowthCurves(group,y,nsim=100,fun=meanT)
Arguments
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.
Details

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.

Value

  • 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
  • Group1name of first group in a comparison
  • Group2name of second group in a comparison
  • Statobserved value of the statistic
  • P.Valueestimated p-value
  • adj.P.Valuep-value adjusted for multiple testing

See Also

compareGrowthCurves, compareTwoGrowthCurves

Aliases
  • compareGrowthCurves
  • compareTwoGrowthCurves
Examples
# A example with only one time
data(PlantGrowth)
compareGrowthCurves(PlantGrowth$group,as.matrix(PlantGrowth$weight))
# Can make p-values more accurate by nsim=10000
Documentation reproduced from package statmod, version 1.2.0, License: LGPL version 2 or newer

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