1. A method of determining the elevation correction factor (ecf) for gravity data from sets of three readings each. It is assumed that elevation does not correlate with geologic structure. If the difference between the height at a station and the weighted mean of the heights of stations on either side of it is hi and the difference between the observed gravity reading at the station and the weighted mean at the neighboring stations is gi (where the weighting is usually taken as inversely proportional to the distance), then the elevation correction factor k is given by:
and the probable error in k is
See Siegert (1942).
2. A method of flying aerogravity or aeromagnetics for reconnaisance mapping. Three closely-spaced lines are flown that are significantly separated from the next set of three lines.