In the sciences, including medicine, the base rate is critical for comparison, so Rufus, coming from that population (science and medicine) understands just what "Base Rate" is.
How many MTJ readers need help in understanding what Base Rate is?
The Bureau of Labor Statistics (BLS) calculates the number of citizens in the Civilian Labor Force (CLF, persons classified as Employed or Unemployed) at 157,833,000 (49% of the U.S. population) and in the Not-in-Labor-Force citizens at 94,610,000 (29% of the population).Jan 12, 2016.
In January, 2016, the base unemployed rate was 5%. That means 5% of 157,833,000 were unemployed (7,891,650 people.) And 95% of 157,833,000 were employed (149,941,350 people.) Math check: 149,941,350 + 7,891,650 = 157833000. Check!
Rufus wrote:Consider what the base numbers of unemployment have been for the past 40 years. That really has not changed all that much - ups & downs - but the base number over time is pretty flat.
2018 - 40 = 1978

Source:
https://tradingeconomics.com/united-sta ... yment-rate