# growthcurve

From statmod v1.2.3
by Gordon Smyth

##### 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 componentsGroup1 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

##### See Also

##### 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 1.2.3, License: LGPL version 2 or newer*

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