From another thread:
""From the data collected, it can be concluded that the delay between the hand start and the electronic start (when arranged by magnitude) is evenly distributed between 0.10 and 0.25 seconds. Therefore, based on this experiment data (and only accounting for human error at the start not the finish line), the average hand-timed 40 yard run is 0.175+/-0.075 seconds “faster” than a fully electronic time"
https://cdn.shopify.com/s/files/1/01...ysis_Paper.pdf
4.55 laser minus 0.175 error for hand-timing = 4.375
4.4 > 4.375
Duke's laser time of 4.55 from the combine is, on average, equivalent to a hand-timed 40 of 4.375. Therefore, despite being bigger, more durable, and far better suited to the NFL, it can be argued that Duke is faster at this weight than he was for that 4.4s hand-timed 40 that you're desperately searching in vain for."
https://www.canesinsight.com/threads/55767-Duke-Johnson-driven-by-promises-to-mother/page2