Survey errors – classification: Systematic errors that persist in a regular pattern during a survey operation are primarily caused by which factor?

Introduction / Context:
Error analysis in surveying separates random (accidental), personal, and systematic components. Correct classification guides prevention: random errors are controlled statistically, personal errors by training, and systematic errors by calibration and adjustment. This question asks for the main cause behind systematic, regularly repeating errors.

Given Data / Assumptions:

• Observations show consistent bias in one direction over repeated measurements.
• Field conditions and procedure remain similar across observations.
• Instrument condition may influence readings in a predictable way.

Concept / Approach:
Systematic errors have magnitude and sign that follow a rule (e.g., index error, collimation error, tape length error, temperature/scale effects). These typically originate from faulty calibration, imperfect adjustment, or physical defects. In contrast, carelessness or inattention cause sporadic blunders or personal/random errors without a steady bias.

Step-by-Step Solution:

Verification / Alternative check:
Two-peg test for levels, collimation checks for theodolites, and tape standardization all target the detection and removal of systematic instrument errors.

Why Other Options Are Wrong:

• Carelessness and inattention lead to random or gross blunders, not consistent, law-like biases.
• “None of these” is wrong because faulty instruments are a classic source of systematic error.

Common Pitfalls:
Attributing a persistent bias to “bad luck”; failing to re-run checks when suspecting instrument error; neglecting temperature or tension corrections for tapes and EDM calibration for distances.

Final Answer:
Faulty or imperfectly adjusted instrument