Social experiments began in the United States as a test of the negative income tax concept in the late 1960s and since then have been conducted on all the populated continents.
Percobaan sosial dimulai di Amerika Serikat sebagai ujian konsep Pajak Penghasilan Negatif di akhir tahun 1960an dan sejak saat itu telah dilakukan di semua benua yang berpenduduk.