Break your problem down into progressively smaller parts.
To create a hierarchical chart:
Step 2: Next, create a hierarchical chart of your factors.
Step 3: Write down a factor; then write down the factors that make up the next level of detail.
Step 4: For each factor, repeat the process.
Step 5: Keep on drilling down until you can’t break them down any further (use the Appreciation tool).
Step 6: Connect the hierarchical structures together into a cohesive whole.
This tool will help you highlight exactly where further research is needed.
Here's an example of a hierarchical chart: