Methods, apparatus, systems, and articles of manufacture are disclosed to generate synthetic respondent level data. An example method includes generating, by executing an instruction with a processor, a seed panel, the seed panel including monitored panelists selected based on a population associated with return path data; comparing, by executing an instruction with the processor, a target rating to a current rating corresponding to the seed panel; and adjusting, by executing an instruction with the processor, the seed panel based on the comparison.