What does a mean error of 15 m in GPS indicate about positional accuracy?

A mean error of 15 m in GPS signifies that, on average, the errors in position readings are 15 m from the true location. This statistical measure gives insight into the distribution of positional errors. The correct interpretation is that approximately 95% of all recorded errors fall within a certain range around that mean error, often within a specific standard deviation.

In GPS, this means that if the mean error is 15 m, it typically suggests that the majority of errors are slight and that you can expect most positional readings to be within a reasonable proximity of the actual position, but not necessarily all points will be accurate to within that mean. The significance of 95% alludes to a statistical threshold commonly used to quantify the uncertainty in measurements, thus indicating that while the average error is 15 m, many readings could be more accurate, and a tailored assessment could help minimize large outliers.

Other options mistakenly suggest certainty in accuracy or interpret the data in a way that doesn't correspond with the standard statistical understanding of mean error. For instance, claiming that all readings are accurate within 15 m would ignore the fact that "mean" incorporates outliers, and indicating that only 5% of readings are accurate would misinterpret the distribution of errors inherent in