The number of milliseconds to wait between samples of the
object identified in cifthThresholdObject. To encourage
consistency in sampling, the interval is measured from the
beginning of one check to the beginning of the next and the
timer is restarted immediately when it expires, not when the
check completes.
This object is not instantiated when the value of
cifthThresholdType is 'rateOfIncreaseExponentXIfSpeed'.