DPOJet Measurement Population Question

Hi,
We are using DPOJet software (version 10.3.0.5) on a MSO72304DX oscilloscope. We are attempting to characterize a 1.6Gbps SerDes PRBS-7 signal at the far end of our harness. I have DPOJet configured to perform several different measurements. One of the measurements is a basic eye height measurement of transition and non-transition bits. Specifically for the Height measurement, what does the Population column in the Measurements Results represent? We typically collect enough data so that our minimum population size is 20. Does this imply that eye height was only measured for 20 UIs or bits? In contrast, something like a Period measurement will typically have a vastly larger population. Is there a reason why the population would be so small for a height measurement vs the period measurement?

Thanks!