Systematic Errors:

Systematic errors follow a few specific pattern according to some mathematical or physical law. The error could be cumulative, i.e. occurring in the similar direction and tends to accumulate affecting the accuracy of measurements to a great extent. Within the context of chain surveying, these could be because of:

(a) Erroneous length of chain or tape (+ve or -ve),

(b) Erroneous ranging,

(c) Links in chain not straight (local bends) due to rough handling or twisting of metallic tapes and etc.,

(d) Non-horizontally of tape / chain over rough ground terrain,

(e) Sag in chain or tape, when it is stretched across a depression in ground,

(f)  Variation within temperature and/or dampness, and

(g) Variation in pull applied during measurement.

These errors could be recognized and adjusted and could be modelled. Suitable corrections could be applied to the measurements for acquiring greater accuracy.