Complex sentence: Impulse buying consists of purchasing a product or service without any previous intent to make that purchase and has been speculated to account for as much as eighty percent of all purchases Smith, D. (1996).
Split into simpler sentences: Impulse buying consists of purchasing a product or service without any previous intent to make that purchase. It has been speculated to account for as much as eighty percent of all purchases Smith, D. (1996).