The two waves measured days of use differently. March asked a single overall question whose response options were these three groups, while August asked day counts for each service separately, which we collapsed into the same groups.
【方法】调查方法存在重要差异:三月询问整体使用情况,而八月询问每个服务的单独使用天数。这种差异可能导致数据解释偏差,因为八月的方法可能低估实际使用频率(例如,使用多个服务的人可能被计数为使用天数而非总使用次数)。