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Receiver Autonomous Integrity Monitoring is most often described using an example where six pseudoranges estimate four unknowns. In this paper, the implications of using only five satellites are investigated. An earlier paper showing that least-squares estimations involving one degree of freedom with equally weighted observations always result in residuals with a value of ±1 is reviewed. The results from this previous work are generalized for the case of weighted observations and a priori knowledge of measurement variance. The new general result is that, when there is one degree of freedom, the standardized residuals always equal ± the square root of the estimate variance factor. This result is then demonstrated using an epoch of real data collected during a vehicle navigation test in an urban canyon where six and then five pseudorange observations are available.