It really depends on your knowledge, what kind of data do you collect and analyze. However, the most used methods are:
1. Mean, average - allows for determining the overall trend of a data set, as well as the ability to obtain a fast and concise view of the data
2. Standard deviation – a method of statistical analysis that measures the spread of data around the mean
3. Regression - is the relationship between a dependent variable (the data you’re looking to measure) and an independent variable (the data used to predict the dependent variable)
4. Statistical process control - statistical techniques to control a process or production method. This method can help you monitor process behavior, discover issues in internal systems, and find solutions for production issues. Statistical process control is often used interchangeably with statistical quality control.
5. Pareto analysis - simple decision-making technique for assessing competing problems and measuring the impact of fixing them. This allows you to focus on solutions that will provide the most benefit.