A-12 
Step 4: Percent compliance by date. 
sample date 
percent 
space 
date 1 
75.00% 
date 2 
18.75% 
date 3 
18.75% 
date 4 
43.75% 
date 5 
12.50% 
Step 5. Rank the percent of space values 
and assign percent of time = (100*R/(M+1.0)), 
where R is rank and M is total number of dates. 
sample date 
ranked 
percent 
space 
cumulative 
percent time 
date 1 
75.00% 
16.67 
date 4 
43.75% 
33.33 
date 2 
18.75% 
50.00 
date 3 
18.75% 
66.67 
date 5 
12.50% 
83.33 
Steps 6 and 7: The plot of the CFD 
and the comparison to the reference 
curve are shown in Figure 2.2. For 
this hypothetical case the assessment 
area would be judged in noncompli¬ 
ance. For a percent area of 18.75, the 
allowable frequency on the reference 
curve is about 53%. That is, 18.75% 
of the segment area should not be out 
of compliance more that 53% of the 
time. For date 3, the estimated 
frequency of 18.75% noncompliance 
is 66.67%. Thus the frequency of 
18.75% of space out of compliance is 
in excess of the 53% allowed. The 
reference curve is exceeded for dates 
4 and 1 as well. Note: in this cumula¬ 
tive distribution framework, the actual 
date is not relevant. One should not 
infer that noncompliance occurred on 
that date if the data point associated 
with a date falls above the reference. 
Date is being used here as a label for 
each coordinate pair. 
Figure 2.2. Graphical representation of CFD from the above example (' + ') with hypothetical reference 
curve ( smooth). 
