Table 1.

Structure of the data set of call detail records before and after preprocessing.

Variable		Before preprocessing	After preprocessing
Number of participants		26	21
	Female	20	16
	Male	6	5
Age (years), range		71-91	71-91
Age (years), mean (SD)		84 (4)	83 (4)
Total number of calls
	Outgoing	19,198	18,338
	Incoming	20,062	17,879
Average number of calls per individual, first quartile
	Outgoing	285	481
	Incoming	579	605
Average number of calls per individual, median
	Outgoing	590	710
	Incoming	718	800
Average number of calls per individual, third quartile
	Outgoing	944	1096
	Incoming	947	992