Often small changes lead to big changes. Small changes can be early warnings of bigger changes to come in the future. In particular when specification limits are wide, small changes in vital sign behavior as identified by a control chart allow the caregiver to view vital signs as they are changing, before the major event happens. Statistics are numbers, which represent some aspect of the entity or process being monitored. Vital sign measurements are numbers that measure the behavior of a patient's bodily functions.
Vital signs are statistics.
Using the manual recording method of the current system it is impossible to collect and record all vital sign measurements for a given patient. Current practice is to collect and record one vital sign per hour or per half an hour maximum. Using computerized SPC methods most vital signs for a patient for a given time period can be collected and recorded. Some monitor-computer combinations collect data every heart beat while others may collect an observation once every five seconds. Some long-term data collecting procedures collect one observation every 15 seconds.