Types of errors in surveying: Which statements correctly describe mistakes, systematic errors, and accidental (random) errors in practice?

Introduction / Context:
Quality in surveying depends on understanding error sources and handling them appropriately. Distinguishing between blunders (mistakes), systematic errors, and accidental (random) errors guides instrument checks, field procedures, and data adjustments.

Given Data / Assumptions:

• Mistakes are human errors and should be detected and removed.
• Systematic errors have identifiable causes and consistent signs.
• Random errors are unbiased and reduce by averaging.

Concept / Approach:
Mistakes (e.g., transposed digits, wrong point sighted) are not statistical errors and must be eliminated via checks. Systematic errors (e.g., scale error, collimation error) can be modeled and corrected; otherwise they bias results consistently. Accidental errors are inherent in observation processes and are treated using statistical methods; they diminish with redundancy roughly as 1/sqrt(n).

Step-by-Step Solution:

Verification / Alternative check:
Closure checks—angular and linear—expose mistakes and systematic trends; residuals after adjustment should resemble random scatter.

Why Other Options Are Wrong:
All statements A–C are correct; D encompasses the full, correct classification widely taught in surveying error theory.

Common Pitfalls:
Attempting to “average out” mistakes or uncorrected systematic errors—averaging only reduces random components, not blunders or biases.

Final Answer:
All of the above