Function used in Excel: NORMDIST(value, mean, SD, TRUE)
Input data:
(1) original value of a patient in the normal distribution
(2) mean value for the normal distribution
(3) size of 1 standard deviation
Steps:
(1) Determine how many standard deviations the value is from the mean.
number of standard deviations from mean =
= ((value) - (mean)) / (size of standard deviation)
(2) Determine the value associated with that number of standard deviations minus 0.01, where:
lower value =
= (mean) + (((number of standard deviations for initial value) - (0.01)) * (size of standard deviation))
(3) Determine the value associated with that number of standard deviations plus 0.01, where:
upper value =
= (mean) + (((number of standard deviations for initial value) + (0.01)) * (size of standard deviation))
(4) Determine the cumulative value for the distribution to the lower value.
cumulative value =
= NORMDIST(lower value, mean, standard deviation, TRUE)
(5) Determine the value for distribution above the upper value
cumulative value for part of curve above the upper value =
= 1 - NORMDIST(upper value, mean, standard deviation, TRUE)
(6) The amount of the distribution about the original value is
value around original value =
= 1 - (cumulative value for curve up to lower value) - (value for curve above the upper value)
