The initial wave of research on the efficiency and effectiveness of fitness trackers and wearables has highlights some of the positive and negative aspects of the technology. While studies have found good retention rates among their subjects (one study saw 80% of participants maintain the use of their fitness tracking device after three months), some questions have been raised about the accuracy of the devices, which have been found to be inaccurate by as much as 15-30% when compared to laboratory measurements of calories burned. While some participants in research studies valued the extra motivation their wearables gave them, many stated that the technology brought pressure to reach goals and made them feel guilty about their eating and exercise behaviour.