A medical researcher wishes to use information about patients that is collected in treatment of a particular hearing problem. Data are recorded in a national database each time a patient visits one of the clinics that provide treatment for the particular problem. This includes the treatment given at each visit. Before she uses the data, the researcher wants to know the reliability of the database record of the treatment provided. She must compare the information in the database with the treating specialists' medical records from the clinics. She wants an estimate of the proportion of visits for which the treatment recorded in the database agrees with the treatment in the clinics' records. Which of the following are true? {Tick all that apply.) 0 All medical records must be compared with their corresponding database entries to estimate the proportion correct in the database. The population comprises all the clinics providing treatment for the hearing problem of interest. 0 The population comprises all the patients with the hearing problem of interest. 0 The population comprises all the visits of patients with the hearing problem of interest. 0 Sampling would not provide reliable information