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The Selection Bias could be produced by stratas
not well defined, or by some strata being over-represented in the sample. The Interpretation Bias comes from questions that are not clear enough or that the subject does not understand, for being too technical, or simply because of the language. Inmigrants or native groups may not have a good knowledge of the language used in the survey. The Recall Bias asking for events that happened a long time ago can leed to wrong answers. Where you ever vaccinated against tetanus? The Non response Bias Why the question is not answered? Is it not clear?; Is it too personal?. Is there a negative interaction with the interviewer? Is the subject afraid of answering Yes?. |