Saudi Arabia, with a smaller population than California, gains or loses a trillion dollars in asset values each time the oil price moves by $4.

Judge as of September 2007. The claim has two parts: (a) Saudi Arabia's population was smaller than California's, and (b) a $4 change in the oil price changes the value of Saudi oil assets by about $1 trillion. Part (a) is checked against 2007 population figures (UN/World Bank or Saudi census for Saudi Arabia; US Census Bureau or California DOF for California). Part (b) is checked by arithmetic: Saudi proven reserves as reported in 2007 (about 260 billion barrels in the BP Statistical Review or OPEC data) multiplied by $4. True: Saudi population was below California's, and reserves × $4 comes to roughly $1 trillion (within about ±25%, i.e. $0.75–1.25 trillion). Mostly true: both hold, but the value implied is somewhat further off (roughly $0.6–1.5 trillion), or the population comparison is very close or depends on counting only Saudi citizens. Mixed: one part holds and the other clearly fails. Mostly false: the population comparison holds but the implied value is off by a factor of about 2–4, or the figure works only on an unusual basis the claim does not state. False: both parts fail, or the asset-value figure is off by more than a factor of 4 (for example, reserves × $4 is about $1 billion).

Set before the research began.

1. E1 Saudi Arabia (06/07) U.S. Department of State (archived Background Note)

   “Population (2007 est.): 27.6 million (22.0 million Saudis, 5.6 million foreign nationals).”

2. E2 Saudi Arabia (06/07) U.S. Department of State (archived Background Note)

   “Proven reserves are estimated to be 263 billion barrels, about one-quarter of world oil reserves.”

3. E3 Energy in Saudi Arabia - Wikipedia Wikipedia · 25 December 2008

   “In January 2007, Saudi Aramco's proven reserves were estimated at 41.3 billion m3 (259.9 billion bbl), comprising about 24% of the world total.”

4. E4 Saudi Arabia (06/07) U.S. Department of State (Background Note, archived) · June 2007

   “Population (2007 est.): 27.6 million (22.0 million Saudis, 5.6 million foreign nationals).”

5. E5 Saudi Arabia (06/07) U.S. Department of State (Background Note, archived) · June 2007

   “Proven reserves are estimated to be 263 billion barrels, about one-quarter of world oil reserves.”

6. E6 Energy in Saudi Arabia - Wikipedia Wikipedia · 25 December 2008

   “In January 2007, Saudi Aramco's proven reserves were estimated at 41.3 billion m3 (259.9 billion bbl), comprising about 24% of the world total.”

7. E7 Energy in Saudi Arabia - Wikipedia Wikipedia · 25 December 2008

   “some energy experts are convinced that current reserves are substantially lower than those officially claimed by Saudis and that the depletion rate is substantially faster.”

8. E8 Governor's Budget State of California, Governor's Budget 2008-09 (Demographic Information) · 1 January 2008

   “The July 1, 2007, estimate of the population is 37,771,000.”

9. E9 Saudi Arabia Encyclopedia.com · 29 May 2018

   “The population of Saudi Arabia in 2005 was estimated by the United Nations (UN) at 24,573,000, which placed it at number 46 in population among the 193 nations of the world.”

10. E10 Saudi Arabia Encyclopedia.com · 29 May 2018

    “While the Saudis maintain over a quarter of the world's known oil reserves (about 263 billion barrels at the end of 1999), these reserves, at the current rate of production, will last only 87.5 years.”

The State Department's 2007 estimate puts Saudi Arabia's population at 27.6 million (E1/E5). California's budget document gives 37,771,000 for July 1, 2007 (E9), so part (a) holds. Proven Saudi reserves were about 263 billion barrels per the State Department (E2/E6), or 259.9 billion in January 2007 per Wikipedia (E4). Multiplying either figure by $4 gives about $1.04–1.05 trillion, which is inside the ±25% band in the criteria, so part (b) also holds.