You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Non - sampling errors may occur due to all the following except- and explain in detail?
Errors may occur not only due to error in sample survey but also due to inadequately calibrated instruments, observer variation, incomplete coverage, and conceptual errors. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 913