组距

组距	zǔ jù	class interval (statistics)
组	Zǔ	surname Zu
组	zǔ	to form / to organize / group / team / classifier for sets, series, groups of people, batteries
距	jù	to be at a distance of ... from; to be apart from / (bound form) distance / spur (on the leg of certain birds: gamecock, pheasant etc)