Observed and predicted CME speeds. The black stars represent the higher of the two CME speeds derived from a geometric fit of observations from each of the two STEREO spacecraft (HELCATS catalogue). The green inverted triangles show the higher of the two CME speeds measured in the STEREO/COR2 images by Gopalswamy et al. (2013). The blue circles and blue triangles are the speeds resulting from multi-spacecraft modelling by Möstl et al. (2014) and Shi et al. (2015). The red filled squares denote the speeds found from the microwave fluence by using least squares (LS) fitting.