Embodiments of the present invention relate to a method of data analysis, comprising comparing a data point in a data stream and a previous data point in the data stream to identify a change direction of the data point based on a difference between the data point and the previous data point, comparing the change direction with a previous change direction to identify whether a trend change occurred for the data point, and identifying a change point that comprises a discrete data value in the data stream based on the trend change. The method also comprises comparing the change point with other data.