Quality tools in ITSM

Answer:
Tools used for quality control have similarities in how we (in ITSM) control quality of delivered services.
Some of the tools that are used to control quality in development and delivery of IT services are:
Testing - to ensure that user's requirements and (quality) expectations are met
Fishbone (or Ishikava) diagram . in e.g. problem resolution
Trend analysis - reporting and trend monitoring is one of the ISO 20000 requirements
Histograms - used to have clear picture of services delivered over longer period of time
Cause and effect analysis - in incident, problem or change management

To read more about Quality Management (applicable to IT service delivery), read the article How to use quality control tools to improve your QMS https://advisera.com/9001academy/blog/2017/04/18/how-to-use-quality-control-tools-to-improve-your-qms/