@TechReport{ it:2022-008, author = {Torsten S{\"o}derstr{\"o}m and Umberto Soverini}, title = {Analyzing the Parameter Bias when an Instrumental Variable Method is Used with Noise-Corrupted Data}, institution = {Department of Information Technology, Uppsala University}, department = {Division of Systems and Control}, year = {2022}, number = {2022-008}, month = oct, abstract = {When an output error model is fitted to data with noise-corrupted inputs using a prediction error method, a bias occurs. It was previously shown that the bias is of order $O(1/\delta)$ for a small pole-zero separation $\delta$. These notes examine the same problem when an instrumental variable model is fitted. A similar result is shown to hold for the instrumental variable case.} }