Error theory as an exam actually tests it: systematic versus random error, standard deviation, propagation through sums and products, weights, and closure tolerances.
What this subject area expects
Compute the mean, standard deviation and standard error of a set of observations
Propagate random error through a sum, a series and a product
Form weights from standard deviations and compute a weighted mean
Judge a traverse or level loop against a stated tolerance
Topics covered here
Error types · Mean and residuals · Standard deviation · Standard error of the mean · Error multipliers · Propagation in a sum · Propagation in a series · Propagation in a product · General error propagation · Weights and weighted means · Relative precision · Closure tolerances · Significant figures