Method, carried out by at least one of a navigation satellite system receiver, hereinafter abbreviated as "NSS receiver", and a processing entity capable of receiving data from the NSS receiver, for estimating, or processing a prior estimation of, parameters derived from NSS signals useful to determine a position, and for generating at least one protection level for an application relying on NSS observations to produce an estimate of said parameters or a combination thereof, wherein a protection level is a statistical error bound ensuring that the estimate only exceeds the protection level with a probability, hereinafter referred to as the "integrity risk", the method comprising: computing a float solution using NSS signals observed by the NSS receiver; searching for, based on the float solution, and identifying an integer ambiguity combination that minimizes an error norm, the identified integer ambiguity combination being hereinafter referred to as "best integer ambiguity combination", and the error norm of an integer ambiguity combination representing a distance from the integer ambiguity combination to the float solution; identifying, among a set of other integer ambiguity combinations determined based on the float solution, those integer ambiguity combinations, hereinafter referred to as "additional integer ambiguity combinations", having the smallest error norms that, together with the error norm of the best integer ambiguity combination, jointly satisfy the integrity risk; computing a measure of spread of at least one of: (i) the best integer ambiguity combination and the additional integer ambiguity combinations, and (ii) values of a parameter or of parameters derivable from the best integer ambiguity combination and the additional ambiguity combinations; and generating the at least one protection level based on the computed measure of spread. computing a float solution using NSS signals observed by the NSS receiver; searching for, based on the float solution, and identifying an integer ambiguity combination that minimizes an error norm, the identified integer ambiguity combination being hereinafter referred to as "best integer ambiguity combination", and the error norm of an integer ambiguity combination representing a distance from the integer ambiguity combination to the float solution; identifying, among a set of other integer ambiguity combinations determined based on the float solution, those integer ambiguity combinations, hereinafter referred to as "additional integer ambiguity combinations", having the smallest error norms that, together with the error norm of the best integer ambiguity combination, jointly satisfy the integrity risk; computing a measure of spread of at least one of: (i) the best integer ambiguity combination and the additional integer ambiguity combinations, and (ii) values of a parameter or of parameters derivable from the best integer ambiguity combination and the additional ambiguity combinations; and (i) the best integer ambiguity combination and the additional integer ambiguity combinations, and (ii) values of a parameter or of parameters derivable from the best integer ambiguity combination and the additional ambiguity combinations; and generating the at least one protection level based on the computed measure of spread.