TNS uses a diary system in about 1,000 homes, while Nielsen has equipped 700 homes with product scanners.
Laurent Zeller, ACNielsen Asia-Pacific managing director of new business development and sales, said it was "foolish" to use a diary-based system in developed markets. "The level of compliance in a diary system is not as good as electronic means. In fast-paced cities, people are busy and not so keen to write."
Zeller claimed that leading consumer goods companies such as Nestle, Procter & Gamble and Unilever, and three local supermarket groups support its system.
TNS Singapore MD Grant Bertoli countered its rival's claims, saying its larger sample size would ensure accurate information on smaller product categories and breakdowns on ethnic and demographic groups.