Digit ratio measurement guide

Literature on Digit Ratio is rapidly growing in Economics. Quite surprisingly we observe that there is no consensus about how to make an accurate measurement in such a delicate task. Along this brief document we offer some concise guidance of how to scan the hands using digital scanners and provide a comprehensive guideline to make a reliable measurement of the 2D:4D. Furthermore, we point out the most common imaging and measurement errors. We also provide a number of hints aimed to avoid these errors that in some cases may cause systematic inaccuracies.