# mark.H0: Mark a point null hypothesis in an HE plot In heplots: Visualizing Hypothesis Tests in Multivariate Linear Models

## Description

A utility function to draw and label a point in a 2D (or 3D) HE plot corresponding to a point null hypothesis being tested. This is most useful for repeated measure designs where null hypotheses for within-S effects often correspond to (0,0).

## Usage

 `1` ```mark.H0(x = 0, y = 0, z=NULL, label, cex = 2, pch = 19, col = "green3", lty = 2, pos = 2) ```

## Arguments

 `x` Horizontal coordinate for H0 `y` Vertical coordinate for H0 `z` z coordinate for H0. If not NULL, the function assumes that a `heplot3d` plot has been drawn. `label` Text used to label the point. Defaults to `expression(H[0])` in 2D plots. `cex` Point and text size. For 3D plots, the function uses `size=5*cex` in a call to `points3d`. `pch` Plot character. Ignored for 3D plots. `col` Color for text, character and lines `lty` Line type for vertical and horizontal reference lines. Not drawn if `lty`=0. `pos` Position of text. Ignored for 3D plots

## Value

None. Used for side effect of drawing on the current plot.

## Author(s)

Michael Friendly

`cross3d`, ~~~
 ```1 2 3 4 5 6``` ```Vocab.mod <- lm(cbind(grade8,grade9,grade10,grade11) ~ 1, data=VocabGrowth) idata <-data.frame(grade=ordered(8:11)) heplot(Vocab.mod, type="III", idata=idata, idesign=~grade, iterm="grade", main="HE plot for Grade effect") mark.H0() ```