Answer :  1. Suitability of data - The data suited for one study need not necessarily be suited to another study. Scrutinise the terms, units of collection, etc. and ensure the collected data is valuable for your study. 2. Reliability of data - The collected data must be reliable. Reliability can be determined by identifying what were the data sources, how the data was collected and who collected the data. 3. Adequacy of data - The gathered secondary data must have a high level of accuracy for successful completion of the study.