I write about applications of data and analytical techniques like statistical modelling and simulation to real-world situations. I show how to access and use data, and provide examples of analytical products and the code that produced them. https://freerangestats.info How much crude oil does the world have in its ready-to-use stocks? Data is collected by the Joint Organizations Data Initiative (JODI) but rarely presented as a total due to missingness and other issues. I do my best in showing at least the stocks of consistently reporting countries, which includes most but not all of the major countries we're be interested in. Tue, 06 Oct 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/10/06/world-crude-stocks https://freerangestats.info/blog/2026/10/06/world-crude-stocks Bias-corrected and adjusted bootstrap does an ok job at confidence intervals of the mean from some example skewed distributions. Better than does relying on the traditional methods of just assuming normality from the central limit theorem. But for particularly awkward distributions, sample sizes are still needed in the thousands to get coverage that resembles the claimed coverage. Sun, 20 Sep 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/09/20/clt-boot-comparison https://freerangestats.info/blog/2026/09/20/clt-boot-comparison It takes a larger sample size than you might hope for the mean of a sample to have a distribution that's close enough to 'normal' for common inference methods to work. Wed, 16 Sep 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/09/16/clt-simulations https://freerangestats.info/blog/2026/09/16/clt-simulations A chart of petrol ('gasoline') prices in the USA and New Zealand since 2004 to now. Petrol is more expensive in New Zealand than the USA—around US$7 per gallon in fact. Sat, 08 Aug 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/08/08/petrol-prices https://freerangestats.info/blog/2026/08/08/petrol-prices Code for an updateable chart of crude oil stocks for the USA as a whole; and a pointer to a new page I'm maintaining of up-to-date monitoring of the fuel crisis. Sat, 01 Aug 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/08/01/fuel-crisis https://freerangestats.info/blog/2026/08/01/fuel-crisis Code for an updateable chart of crude oil stocks at the importing Cushing facility in the USA. Thu, 09 Jul 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/07/09/cushing https://freerangestats.info/blog/2026/07/09/cushing I draw some charts of GDP per capita growth from 1900 to 2023, for various countries, using data from the excellent Maddison Project in economic history at the Groningen Growth and Development Centre. Sun, 28 Jun 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/06/28/long-term-growth https://freerangestats.info/blog/2026/06/28/long-term-growth UK has had a spurt of prime ministerial turnover in the past decade or so, but it's by no means unprecedented. I download data from Wikipedia and try several ways to visualise that turnover. Tue, 23 Jun 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/06/23/uk-prime-ministers https://freerangestats.info/blog/2026/06/23/uk-prime-ministers Seasonal adjustment is easy but getting hold of data can be hard. In this case I wrangle Samoa's monthly visitor arrivals data from 2017 to present and then use the seas and fable R packages to seasonally adjust it and ask if there is an impact from Iran war fuel crisis (there isn't evidence of one yet). Sun, 14 Jun 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/06/14/samoa-seasonal-adjustment https://freerangestats.info/blog/2026/06/14/samoa-seasonal-adjustment Modern wars on average last longer than a year, but the distribution is very right-skewed. Conditional on a war lasting 74 days and with no information available other than past durations, the median total duration is 261 days, and an 80% prediction interval would be (95, 1,752) days. Wed, 13 May 2026 00:00:00 +0800 https://freerangestats.info/blog/2026/05/13/war-durations https://freerangestats.info/blog/2026/05/13/war-durations