A Wireless Sensor Network (WSN) composed of tiny sensor nodes may operate in an unfavorable terrain. The coupling of inherent limitations and harsh environments makes WSNs fallible. For this reason, reliability becomes one of the most important issues in WSN research. Some of the early work in the field of detection reliability focuses on collaborative effort. Instead of the collaborative work, the sensing improvements are proposed for detection reliability enhancement. Two types of detection models are constructed based on the scenarios of WSN operations for probability decomposition. The fault probability of detection and the probability of detection reliability in WSNs can then be estimated based on the decomposition of probabilities and empirical data. In analyzing the decomposition of probabilities, sensing improvements are shown to enhance detection reliability. An illustrative example is demonstrated to show how detection reliability can be controlled by different sensing improv...