What does the network positional accuracy of a control point quantify?

What does the network positional accuracy of a control point quantify?

• A. The uncertainty in the coordinates of the control point with respect to the geodetic datum at the 95-percent confidence level.
• B. The time stability of the control point coordinates.
• C. The average distance between control points in the network.
• D. The precision of measuring instruments used in data collection.

Answer: (A)

The network positional accuracy is about how uncertain the computed coordinates of a control point are after the network is adjusted, relative to the geodetic datum. This uncertainty comes from the propagation of measurement errors through the network solution, and it is usually expressed as a 95% confidence region (often a 3D ellipsoid) around the point’s coordinates. In practice, the smaller this accuracy value, the more precisely the point’s position is known with respect to the datum. It’s not about how long the point’s coordinates stay the same over time, not about how far apart control points are from each other, and not about the precision of the surveying instruments themselves—those relate to stability, point density, or instrument capability rather than the resulting coordinate accuracy within the datum.

The network positional accuracy is about how uncertain the computed coordinates of a control point are after the network is adjusted, relative to the geodetic datum. This uncertainty comes from the propagation of measurement errors through the network solution, and it is usually expressed as a 95% confidence region (often a 3D ellipsoid) around the point’s coordinates. In practice, the smaller this accuracy value, the more precisely the point’s position is known with respect to the datum. It’s not about how long the point’s coordinates stay the same over time, not about how far apart control points are from each other, and not about the precision of the surveying instruments themselves—those relate to stability, point density, or instrument capability rather than the resulting coordinate accuracy within the datum.