Complex sentence: Sir Roy Forbes Harrod (1900-1978) was an English economist, who Independently of Evsey Domar developed an important economic model called the Harrod-Domar model.
Split into simpler sentences: Sir Roy Forbes Harrod (1900-1978) was an English economist. He, independently of Evsey Domar, developed an important economic model now called the Harrod-Domar model.