* Data Collection Challenges: Tracking the exact number of doctorate degrees awarded and the total US population requires compiling data from various sources, and there's always a time lag in data reporting.
* Definition of "Person": The denominator ("people in the US") can be ambiguous. Do we include children, non-citizens, etc.? The choice impacts the ratio.
* Degree Type: The type of doctorate matters (Ph.D., Ed.D., etc.). A combined figure would mask important distinctions.
To get an approximation, you would need to find recent data on:
* Total population of the US: From the US Census Bureau.
* Number of doctorate degrees awarded annually: From the National Center for Education Statistics (NCES). This would need to be summed over a period of years to get a reasonable estimate of the total number of doctorate holders. You'd also need to account for those who have earned doctorates but have died or emigrated.
Even with this data, the resulting ratio would be a rough estimate, and its accuracy would depend on the timeliness and comprehensiveness of the source data. You would likely find different estimates depending on the sources and methods used.