Successful integer estimation of carrier phase ambiguities of Global Naviga
tion Satellite Systems (GNSS) is the key to many high precision positioning
applications. In order to describe the quality of the positioning results
rigorously, one needs to know the probabilistic properties of both the inte
ger and noninteger parameters in the GNSS model. In this contribution these
probability distributions are presented and discussed. The probability mas
s function of the integer ambiguities is needed to evaluate the ambiguity s
uccess rate and the distribution of the GNSS baseline is needed to evaluate
the relevant confidence regions for positioning.