98991114_rime_in_the_United_States_2006__Reason_for_Estimation
[Year] 1993 [State(s)] Illinois [Estimation Method] Since valid annual totals were available for approximately 60 Illinois agencies, those counts were maintained. The counts for the remaining jurisdictions were replaced with the most recent valid annual totals or were generated using standard estimation procedures. The results of all sources were then combined to arrive at the 1993 state total for Illinois. [Reason for Estimation] 
NIBRS conversion efforts resulted in estimation for Illinois.
Table 01, Data Declaration - Crime in the United States 2006
Reason for Estimation