The local positional accuracy of a control point is a number that represents the uncertainty at the 95% confidence level in coordinates relative to what?

The local positional accuracy of a control point is a number that represents the uncertainty at the 95% confidence level in coordinates relative to what?

• A. Elevation differences to the reference point
• B. The density of monuments in the area
• C. The uncertainty in coordinates of this control point relative to adjacent connected or measured control points at 95% confidence
• D. The coordinates of this point only

Answer: (C)

Local positional accuracy is about how well a control point’s position is known within the surrounding network. The 95% confidence level means the plotted position has a statistical envelope showing where the true position is likely to be, based on how the point is connected and measured against neighboring points. In other words, it reflects the uncertainty of this point's coordinates relative to adjacent connected or measured control points, derived from the network adjustment. This relative, network-based uncertainty is what matters for ensuring the control point fits consistently with the rest of the survey network, not the absolute value of the point alone. The other ideas don’t fit because elevation differences are vertical, which is a different type of accuracy; the density of monuments doesn’t determine the statistical uncertainty; and focusing on the coordinates of this point alone ignores how it relates to the rest of the network, which is essential for local positional accuracy.

Local positional accuracy is about how well a control point’s position is known within the surrounding network. The 95% confidence level means the plotted position has a statistical envelope showing where the true position is likely to be, based on how the point is connected and measured against neighboring points. In other words, it reflects the uncertainty of this point's coordinates relative to adjacent connected or measured control points, derived from the network adjustment. This relative, network-based uncertainty is what matters for ensuring the control point fits consistently with the rest of the survey network, not the absolute value of the point alone.

The other ideas don’t fit because elevation differences are vertical, which is a different type of accuracy; the density of monuments doesn’t determine the statistical uncertainty; and focusing on the coordinates of this point alone ignores how it relates to the rest of the network, which is essential for local positional accuracy.