I know this has been asked before, but the basic answer was "it depends on the context". Hence, I will provide "my" context here. Prepositions are always puzzling because there is no (straightforward) rule. This time I'm struggling to find the correct preposition for the the term "understanding of/about".
Here are three sample sentences I used this phrase:
1. Knowing how the SIAB is structured should also give the reader a better understanding about/of the strengths and weaknesses of the administrative dataset at hand.
2. Before we discuss our estimates for the causal effect of agency employment, however, we start with descriptive results whose purpose it is to give the reader a better understanding of/about the labor market trajectories of temporary help workers in general.
3. However, looking at these numbers helps to gain a better understanding of/about the relative size of the effect we present later. It also allows to portray the employment trajectories of the treated and non-treated individuals on a descriptive basis.
If anything else is wrong or sounds odd in the sentences, please let me as well. Thank you in advance!
"... a better understanding of" in all three.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.