Abstract: Compact bursts (CBs) are frequently observed by the Interface Region Imaging Spectrograph (IRIS) in both NUV and FUV channels. They appear as a small and intense, short time-scale brightenings visible in solar active regions, e.g. in emerging flux areas, plages or around sunspots. Modelling of these structures and a statistical analysis based on the IRIS spectra in Mg II h and k lines using large dense rasters will be presented. We develop an algorithm to search CBs using different criteria concerning the enhancement of contrasts at different wavelengths in Mg II k line and their visibility in Si IV, CII lines and Mg II triplet. This analysis allows us to categorise CBs in the way as it was done in Grubecka et al. (2015). We also searched for correlations between the emission of Mg II lines and hotter Si IV line in order to find which of events are linked with IRIS bombs.