Use of Fuzzy Techniques for Detection of Outlier in GPS Networks Sadegh Jamali Faculty Member Zanjan University, Iran Email: jamali@mail.znu.ac.ir Abstract Most of outlier detection methods such as conventional methods based on statistical tests on least squares residuals. The statistical correlation between residuals often decrease the quality of the results. In this paper, fuzzy techniques and the statistical tests are used together to detect the outliers in GPS networks. Unlike conventional methods, no measurement is removed from the observation set, thus the shape of the network isn't defected. This approach is tested on one GPS network and the results have been compared with the results of the conventional method.