Measuring, monitoring, and improving application responsiveness is a common need for many software professionals. Whether you develop applications or manage them, understanding application responsiveness is key to achieving successful applications and happy users. But good characterization of bad data is useless. When measurements of response time present false or misleading latency information, even the best analysis can lead to wrong operational decisions and poor application experience. In this talk, Gil Tene (CTO, Azul Systems) will demonstrate some common pitfalls encountered (far too often) in the real world of response time characterization, along with some demonstrations of what successful characterization looks like.