Analyzing operation of communications network

A computer implemented method for analysis of operation of a communications network comprising:

• obtaining time series of performance data of a cell of the communications network;
• selecting a change point in the time series;
• determining a first linear regression model before the selected change point and a second linear regression model after the selected change point;
• determining offset difference between the first linear regression model and the second linear regression model;
• determining anomaly type based on the offset difference;
• and
• determining an angle difference between the first linear regression model and the second linear regression model and using the angle difference in determining the anomaly type.