Turn “study or work” into a calculation: compare the three years of pay you'd earn by working now against the yearly income gap you'd gain over the next several decades by staying in school

High value
Evidence B
Saves money
Free
Takes minutes
No willpower

In plain words

Going to work now lets you earn a few years of wages sooner, but you collect that money once. Staying in school means earning somewhat more than you otherwise would every year, for 30 or 40 years in a row. So the two sums have to be put side by side. In Chinese cities, one more year of schooling went with roughly 4.0% to 10.2% higher yearly income, but those are figures from before 2001 and give only a rough idea.

Cost: Free. Sitting down to work it out once takes about half an hour.
What you get: This is an estimate for Chinese cities from 1988 to 2001. How much higher income is for one more year of schooling is called the return to education. The original reads: “rising sharply from 4.0% per year of schooling in 1988 to 10.2% in 2001.” The rise came mostly after 1992. It reflects the growing extra pay that people who finished college earn over those who did not (the higher-education wage premium). This is a China-based order of magnitude you can use when turning “one more year” into a yearly income gap. For the global average, see §23.7 (global average return to one more year of education).
Notes: Before calculating, subtract the tuition waivers and stipends in §23.4 (secondary vocational school tuition and stipends), and add the account in §23.2 (extra schooling and death rate). The data end in 2001 and cover only cities, so they can't be used directly as today's figures. The same goes for the global average of 9% in §23.7. If you really do this calculation, the answer will differ from person to person. With high tuition, a major that doesn't match any job, and many years of study, the numbers may truly not add up, but that only shows that this particular program isn't worth it, not that schooling is useless. A few things don't fit in the formula: legal education requirements, see §23.5 (pathway admission and separate exams at secondary vocational schools); resistance to being replaced, see §23.10 (choosing skills that resist automation); and whether you can switch industries. The beneficiary is yourself.
Evidence grade: B : Supported by research but without a precise number, or based on small or single studies.
Sources: Zhang J, Zhao Y, Park A, Song X (2005). Economic returns to schooling in urban China, 1988 to 2001. Journal of Comparative Economics, 33(4), 730-752. https://doi.org/10.1016/j.jce.2005.05.008

Mentioned in

Translated from the Chinese original. Original book, section 23, tip 6. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer