Fig. 4

a Richness time series for the main room and auxiliary rooms of two daycare centers in Oslo, Norway sampled throughout a full year. The gap in auxiliary room richness in May is due to samples being excluded from the analysis because of the low number of reads. b Random forest model showing the importance (percentage of increase in mean squared errors—IncMSE) of each variable for richness of the two indoor datasets, auxiliary and main rooms. Numbers on the bars indicate statistical significance, which was obtained through bootstrapping