The main problem is the compliance workload – that is, the work involved in meeting the requirements and demonstrating that they’ve been met. Therefore, the rules could act as an additional handicap for small banks that are already under pressure from many sides. Take the rapid digitalisation of banking, for example, or the lowinterest-rate environment.
In contrast, the trimmed mean looks at the price changes every month for each item of the CPI and eliminates a certain fraction (e.g., 10 percent) of the most extreme observations at both ends of the largest and smallest changes. Thus, items eliminated each month could vary month to month.