Table 1

Reasons that potential case and control drivers were excluded from the study and reasons that the remaining potentially eligible case and control drivers were not interviewed or not used in the final analysis

Potential cases (n=1521)Potential controls (n=3227)
NA = not applicable.
Reason for exclusion
    Control higher in rank interviewedNA2050
    Vehicle not registered in Washington258210
    Driver younger than 18 years551
    Vehicle fire only12NA
    Parked vehicle23NA
    Vehicle fled scene or stolen6NA
    Driver died10NA
    Not sampled45NA
Total excluded4122261
Number potentially still eligible1109966
Reason no interview was obtained
    Report received too late from patrol10216
    Report not sent by patrol55NA
    Owner name and address not found258
    Staff not available or staff error268
    No telephone number found234187
    Unlisted telephone number8162
    Disconnected telephone1211
    No answer despite multiple calls3448
    Answering machine only85124
    Rental agency refused information510
    Commercial owner could not locate driver before deadline5336
    Other reasons2125
    Presumed owner denied ownership045
    Reached household member, not driver8458
    Household member refused on behalf of driver248
    Driver denied crash or driving at reference time and location331
    Driver did not speak English82
    Driver refused interview5434
Total not interviewed883763
Number interviewed226203
Reason not used in analysis
    Control license numbers not collected7NA
    Controls collected at wrong time22
    Major errors in control interview22
    No control interviewed15NA
Included in final analysis200199