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modehunt (version 1.0.7)

modeHuntingBlock: Multiscale analysis of a density via block procedure

Description

Simultanous confidence statements for the existence and location of local increases and decreases of a density f, computed via the block procedure.

Usage

modeHuntingBlock(X.raw, lower = -Inf, upper = Inf, d0 = 2, 
    m0 = 10, fm = 2, crit.vals, min.int = FALSE)

Arguments

X.raw
Vector of observations.
lower
Lower support point of $f$, if known.
upper
Upper support point of $f$, if known.
d0
Initial parameter for the grid resolution.
m0
Initial parameter for the number of observations in one block.
fm
Factor by which $m$ is increased from block to block.
crit.vals
2-dimensional vector giving the critical values for the desired level.
min.int
If min.int = TRUE, the set of minimal intervals is output, otherwise all intervals with a test statistic above the critical value (in their respective block) are given.

Value

  • DpThe set $\mathcal{D}^+(\alpha)$ (or $\bf{D}^+(\alpha)$).
  • DmThe set $\mathcal{D}^-(\alpha)$ (or $\bf{D}^-(\alpha)$).

Details

See blocks for details how $\mathcal{I}_{app}$ is generated and modeHunting for a proper introduction to the notation used here. The function modeHuntingBlock uses the test statistic $T^+_n({\bf X}, \mathcal{B}_r)$, where $\mathcal{B}_r$ contains all intervals of Block $r$, $r=1,\ldots,\#blocks$. Critical values for each block individually are received via finding an $\tilde \alpha$ such that $$P(B_n({\bf{X}}) > q_{r,\tilde \alpha / (r+tail)^\gamma} \ for \ at \ least \ one \ r) \le \alpha,$$ where $q_{r,\alpha}$ is the $(1-\alpha)$--quantile of the distribution of $T^+_n({\bf X}, \mathcal{B}_r).$ We then define the sets $\mathcal{D}^\pm(\alpha)$ as $$\mathcal{D}^\pm(\alpha) := \Bigl{\mathcal{I}_{jk} \ : \ \pm T_{jk}({\bf{X}}) > q_{r,\tilde \alpha / (r+tail)^\gamma} \, , \ r = 1,\ldots \#blocks\Bigr}.$$ Note that $\gamma$ and $tail$ are automatically determined by $crit.vals$. If min.int = TRUE, the set $\mathcal{D}^\pm(\alpha)$ is replaced by the set ${\bf{D}}^\pm(\alpha)$ of its minimal elements. An interval $J \in \mathcal{D}^\pm(\alpha)$ is called minimal if $\mathcal{D}^\pm(\alpha)$ contains no proper subset of $J$. This minimization post-processing step typically massively reduces the number of intervals. If we are mainly interested in locating the ranges of increases and decreases of $f$ as precisely as possible, the intervals in $\mathcal{D}^\pm(\alpha) \setminus \bf{D}^\pm(\alpha)$ do not contain relevant information.

References

Duembgen, L. and Walther, G. (2008). Multiscale Inference about a density. Ann. Statist., 36, 1758--1785. Rufibach, K. and Walther, G. (2010). A general criterion for multiscale inference. J. Comput. Graph. Statist., 19, 175--190.

See Also

modeHunting, modeHuntingApprox, and cvModeBlock.

Examples

Run this code
## for examples type
help("mode hunting")
## and check the examples there}

<keyword>htest</keyword>
<keyword>nonparametric</keyword>

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