I am using TikZ to make flowchart kind of diagrams. I want to get a node below and to the left of another node. Please see the following example. I want the replicate the sort of relationship between nodes `revealed` and `WTP measurement`. I have done that by creating an empty node directly below `WTP measurement` and then creating node `revealed` to the left of it. Is there an easier way? As you see in the code, I tried

```
   \node [level3, below left=of revealed, node distance=2in] (marketdata) {Market Data};

```

but that does not work. The node `marketdata` is not placed below and to the left of node `revealed`. In fact, it appears above it. 

```
\usemodule[tikz]
\usetikzlibrary[shapes,arrows]

\starttext

% Define block styles
\tikzstyle{level1} = [rectangle, draw, fill=green!40!blue!20, 
    text width=4in, text centered, inner sep=1pt, 
    minimum height=4em]
\tikzstyle{level2} = [rectangle, draw, fill=blue!20, 
    text width=2in, text centered, rounded corners, minimum height=3em]
\tikzstyle{level3} = [rectangle, draw, fill=blue!10, 
    text width=2in, text centered, rounded corners, minimum height=3em]

\starttikzpicture   
   % Place nodes
    \node [level1] (start) {\color[white]{WTP measurement}};
    \node [below of = start, node distance=1in] (blank) { };
    \node [level2, right of = blank, node distance=2in] (stated) {Stated Preference};
    \node [level2, left of = blank, node distance=2in] (revealed) {Revealed Preference};
    \node [level3, below left=of revealed, node distance=2in] (marketdata) {Market Data};

    % Draw edges
    \path [line] (start) -- (stated);
    \path [line] (start) -- (revealed);    
\stoptikzpicture

\stoptext

```