Jan Visman

Who is Jan Visman?

Jan Visman was a Dutch statistician who played a key role in building a bridge between sampling theory with its homogeneous populations and sampling practice with its heterogeneous sampling units and sample spaces.

Visman studied mining engineering at the Delft University of Technology, and was employed at the Dutch State Mines during the Second World War. He surfaced after the war with a massive amount of test results determined in samples selected from heterogeneous sampling units of coal. In fact, he had gathered so much valuable information that he was encouraged to write a PhD thesis on the sampling of coal. Jan Visman defended his PhD thesis titled “De Monsterneming van Heterogene Binomiale Korrelmengsels, in het Bijzonder Steenkool” at the Technical University of Delft on December 17, 1947.

Visman proved that the variance of the primary sample selection stage is the sum of the composition variance and the distribution variance. The composition variance is a measure for variability between particles within primary increments.