1 \documentclass[12pt]{standalone}
4 \usepackage[utf8x]{inputenc}
6 \usepackage[T1]{fontenc}
8 \renewcommand{\rmdefault}{ugm}
9 \renewcommand{\sfdefault}{phv}
10 \usepackage[garamond]{mathdesign}
12 \usetikzlibrary{positioning, shapes, arrows, shadows}
17 observed/.style={circle, draw},
18 partly observed/.style 2 args={draw, fill=#2, path picture={
19 \fill[#1, sharp corners] (path picture bounding box.south west) -|
20 (path picture bounding box.north east) -- cycle;},
22 unobserved/.style={draw, circle, fill=gray!40},
23 residual/.style={draw, rectangle}
28 \node[observed] (y) {$Y$};
29 \node[unobserved, above=of y] (x) {$X$};
30 \node[observed, left=of x] (w) {$W$};
32 \node[observed,right=of x] (z) {$Z$};