The scientific method begins with scientists forming questions, or hypotheses, and then acquiring the knowledge through observations and experiments to either support or disprove a specific theory. "Empirical" means "based on observation or experience," according to the Merriam-Webster Dictionary. Empirical research is the process of finding empirical evidence. Empirical data is the information that comes from the research.
Before any pieces of empirical data are collected, scientists carefully design their research methods to ensure the accuracy, quality and integrity of the data. If there are flaws in the way that empirical data is collected, the research will not be considered valid.
In a scientific sense "empirical evidence" doesn't mean I oberserved a UFO therefore there is life on other planets and they're visiting earth.