User error is the number one cause of false alarms. Installation problems come in second. A very small percentage of false alarms are caused by severe weather and power outages.
A main reason for user error is ignorance of the proper use of the alarm system. Many times, homeowners and business owners don't take the time to understand the workings of their alarm, or they don't take the time to train others on the proper use of the alarm.
Alarms can be set off by faulty contacts on doors and windows. Plants and curtains set off motion detectors, as do pets and changes in atmosphere such as humidity or heat.
Perhaps the greatest number of false alarms happens when someone re-enters an area that has been armed. In these cases, simply knowing where the keypad is, and how to cancel the alarm, would be the solution. But too often, the person setting off the alarm is a visitor to the home, or a night cleaner or other service personnel, who hasn't been told how to cancel an alarm.