Non sampling errors category – UGC NET Question

Non-sampling errors are all sources of survey inaccuracy that do not stem from the act of sampling but from the way data are collected, recorded or processed. They include interviewer bias, faulty questionnaire design, respondent misunderstanding and coding or tabulation mistakes. Such errors can be large and may not decrease simply by increasing sample size. Therefore, errors arising from inaccurate responses or defective tools are correctly termed non-sampling errors.

Option A:
Non-sampling errors encompass diverse problems such as ambiguous questions that confuse respondents, poorly trained interviewers and data entry errors. These issues affect the quality of information gathered from each selected unit and can seriously distort findings. Since the stem emphasises inaccurate responses and processing mistakes, this option is appropriate.

Option B:
Random error refers to unpredictable fluctuations that occur by chance and may be part of both sampling and measurement processes; it is not restricted to the specific systematic problems listed.

Option C:
Proportional error is not a standard category in survey methodology and does not describe the cluster of issues like tool defects and processing mistakes.

Option D:
Experimental error is associated with variability in experimental outcomes and does not specifically refer to survey response or instrument problems, so it is not correct here.