IWTaov | R Documentation |
The function implements the Interval Wise Testing procedure for testing mean differences between several functional populations in a one-way or multi-way functional analysis of variance framework. Functional data are tested locally and unadjusted and adjusted p-value functions are provided. The unadjusted p-value function controls the point-wise error rate. The adjusted p-value function controls the interval-wise error rate.
IWTaov(formula, B = 1000, method = "residuals", dx = NULL, recycle = TRUE)
formula |
An object of class " |
B |
The number of iterations of the MC algorithm to evaluate the p-values of the permutation tests. The defualt is |
method |
Permutation method used to calculate the p-value of permutation tests. Choose " |
dx |
Used only if a |
recycle |
Flag used to decide whether the recycled version of the IWT should be used (see Pini and Vantini, 2017 for details). Default is |
IWTaov
returns an object of class
"IWTaov
". The function summary
is used to obtain and print a summary of the results.
An object of class "IWTaov
" is a list containing at least the following components:
call |
The matched call. |
design_matrix |
The design matrix of the functional-on-scalar linear model. |
unadjusted_pval_F |
Evaluation on a grid of the unadjusted p-value function of the functional F-test. |
pval_matrix_F |
Matrix of dimensions |
adjusted_pval_F |
Evaluation on a grid of the adjusted p-value function of the functional F-test. |
unadjusted_pval_factors |
Evaluation on a grid of the unadjusted p-value function of the functional F-tests on each factor of the analysis of variance (rows). |
pval.matrix.factors |
Array of dimensions |
adjusted.pval.factors |
adjusted p-values of the functional F-tests on each factor of the analysis of variance (rows) and each basis coefficient (columns). |
data.eval |
Evaluation on a fine uniform grid of the functional data obtained through the basis expansion. |
coeff.regr.eval |
Evaluation on a fine uniform grid of the functional regression coefficients. |
fitted.eval |
Evaluation on a fine uniform grid of the fitted values of the functional regression. |
residuals.eval |
Evaluation on a fine uniform grid of the residuals of the functional regression. |
R2.eval |
Evaluation on a fine uniform grid of the functional R-squared of the regression. |
heatmap.matrix.F |
Heatmap matrix of p-values of functional F-test (used only for plots). |
heatmap.matrix.factors |
Heatmap matrix of p-values of functional F-tests on each factor of the analysis of variance (used only for plots). |
Pini, A., & Vantini, S. (2017). Interval-wise testing for functional data. Journal of Nonparametric Statistics, 29(2), 407-424
Pini, A., Vantini, S., Colosimo, B. M., & Grasso, M. (2018). Domain‐selective functional analysis of variance for supervised statistical profile monitoring of signal data. Journal of the Royal Statistical Society: Series C (Applied Statistics) 67(1), 55-81.
Abramowicz, K., Hager, C. K., Pini, A., Schelin, L., Sjostedt de Luna, S., & Vantini, S. (2018). Nonparametric inference for functional‐on‐scalar linear models applied to knee kinematic hop data after injury of the anterior cruciate ligament. Scandinavian Journal of Statistics 45(4), 1036-1061.
D. Freedman and D. Lane (1983). A Nonstochastic Interpretation of Reported Significance Levels. Journal of Business & Economic Statistics 1.4, 292-298.
B. F. J. Manly (2006). Randomization, Bootstrap and Monte Carlo Methods in Biology. Vol. 70. CRC Press.
See summary.IWTaov
for summaries and plot.IWTaov
for plotting the results.
See ITPaovbspline
for a functional analysis of variance test based on B-spline basis expansion.
See also IWTlm
to fit and test a functional-on-scalar linear model applying the IWT, and IWT1
, IWT2
for one-population and two-population tests.
# Importing the NASA temperatures data set
data(NASAtemp)
temperature <- rbind(NASAtemp$milan,NASAtemp$paris)
groups <- c(rep(0,22),rep(1,22))
# Performing the IWT
IWT.result <- IWTaov(temperature ~ groups,B=1000)
# Summary of the ITP results
summary(IWT.result)
# Plot of the IWT results
layout(1)
plot(IWT.result)
# All graphics on the same device
layout(matrix(1:4,nrow=2,byrow=FALSE))
plot(IWT.result,main='NASA data', plot_adjpval = TRUE,xlab='Day',xrange=c(1,365))
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