How do you know your data visualization is correct?

I’ve just completed my final treemap project.

But when it fails one test and it looks slightly different to the FCC example.

But my ‘boxes’ look to have a correct proportion compared to the example, just in different locations.

In the ‘real world’ how would you know if your data visualization is correctly drawn?

I apologize in advance for performing necromancy, but this is an issue I struggled with for quite some time in the beginning as well, so my urge to reply is mighty.

Breaking visualizations up into exploratory and explanatory:
Exploratory visualizations are ‘correct’ when the audience can make sense of them
Explanatory visualizations are ‘correct’ when the designer’s specific intended message is clear to the audience

Specifically addressing your tree map, that would lean more towards exploratory than explanatory. So it is correct when the audience can look around and compare genres and compare movies within and across genres… FCC’s example isn’t just one of many ways to assemble the tree map, but a tree map is one of many ways to present the data at all.