Deleting statistics data and archiving log files on a regular basis helps to control the disk space occupied. However, be aware that the data is no longer available for viewing or creating reports. Make sure that you export the statistics data to another format, or create an archived report file, or copy the archived log file to another directory, if you still want information to be available.
Deleting statistics data or archiving log files on a daily schedule cuts the storage space down to a minimum, but one day's worth of information may not be enough for some reports to be meaningful.