A recent analysis of toddler care indicated that the level of interaction toddlers have during the day influences their naptime. At twelve months, toddlers in the study with a less interactive daytime schedule napped an average of one hour more each day than those with a more interactive schedule. Given that naptime is crucial for a toddler's growth, caregivers should consider minimizing the level of interaction their toddlers experience. Which one of the following statements, if true, most seriously weakens the argument?