The primary focus of the interview questionnaires is to ascertain information on intermediary and outcome variables for the study, including measures for predisposing, reinforcing, and enabling factors for cancer screening.
In order to ascertain information concerning hospital admissions one year before and one year after cholecystectomy (index) admission we obtained records for all admissions from January 1st 1999 through December 31st 2004.
Questions also ascertained information about acute health care use for asthma in the preceding 3 months (emergency department visits, unscheduled doctor visits, and hospitalizations) and rescue medication use in the previous 2 weeks (short-acting beta agonist).
The study retrospectively ascertained information using a questionnaire.
This file will be used to ascertain additional information for Medicare eligible (mostly 65 years and older) patients who may have co-utilized services outside the VA.
Finally, it is worth pointing out that where these biases are present, threshold estimates are likely to be more difficult to ascertain (for information about the influence of order effects on thresholds in two-alternative forced choice paradigms, see García-Pérez & Alcalá-Quintana, 2010; Ulrich, 2010; Ulrich & Vorberg, 2009).
The public use file includes county of residence for births in densely populated counties, which enabled us to ascertain deidentified birth information for all births in most of the counties.
On a similar note, we were unable to ascertain reliable information on contraindications for the study drugs.
At each maternal contact, we ascertained the following information for the infant: the number of household members and siblings, breast-feeding status, cigarette and cooking smoke exposure, symptoms of upper respiratory tract infection, and antibiotic use.
