Trends identify opportunities in markets by analyzing information over time to show long-term patterns. Performing primary research requires choosing a research instrument like questionnaires or interviews to directly contact people using a survey method. Secondary research finds already collected information from other sources. Different survey methods have various considerations like cost, reliability, and flexibility. Common survey types include telephone, mail-in, in-person, and internet questionnaires as well as focus groups. Questionnaires and interviews are very similar but differ in being written versus spoken.