%I need to get the very last level shared between the two upper levels. How can I code that?
\documentclass[tikz,border=10pt]{standalone}
\usepackage{forest}
\usetikzlibrary{shadows}
\begin{document}
\begin{forest}
shade me/.style={%
bottom color=#1!25,
top color=#1!5,
draw=#1,
drop shadow,
font=\large,
},
my label/.style n args=2{%
edge label={node [midway, black, font=\sffamily\large, #1] {#2}}
},
where n children=0{%
shade me=blue!50!cyan,
}{%
if level=0{%
shade me=green!75!gray,
}{%
shade me=blue!75!magenta,
}
},
for tree={%
delay={content/.wrap value={\strut #1}},
edge={red,->},
l sep+=25pt,
s sep+=20pt
}
[100000 individuals
[100 affected, my label={above, xshift=1cm}{}
%[No, my label={above, sloped}{$< 30$}]
[{95\% true positives}, my label={below, xshift=-1.7cm}{}
[{95 + 999 test positive Total = 1094}, my label={above, sloped}{}]]]
[99900 unaffected, my label={above, sloped}{}
[{1\% false positives}, my label={below, xshift=1.5cm}{}
[{95 + 999 test positive Total = 1094}, my label={above, sloped}{}]]] ]
]
]
\end{forest}
\end{document}