Conductive cables have always represented a source of noise in ground-penetrating radar (GPR) data. In some instances, commercially available GPR systems use data processing tools to reduce cable noise. Such processes seldom respect the amplitude fidelity of the signal. For the purpose of careful, quantitative amplitude measurements, use of the raw recorded data is a critical starting point for reliable interpretation of results. During subsequent processing, users can compensate for cable effects to varying degrees. To illustrate the issues inherent with cable noise, we show an example where cable movement during data acquisition generates deviations in reflection amplitude up to 19%. We then present the ramifications of these variations for quantitative data analysis. We conclude that precise cable handling can improve data quality and subsequent data interpretation. Our results are particularly pertinent for quantitative analysis and inversion of GPR data where precise amplitude information is crucial.