Answer:
Long story, see below. The difference in reaction times may have been due to differences in the individuals, not the reactions.
Step-by-step explanation:
We'll make the assumption that both stopwatches are the same, and that they operate by pushing a button to start and stop the timer. Let's assume both Dominic and Eva are doing the same experiment. t is not stated, however, if they are doing the same experiment in the same room, same chemicals, and same protocol. Let's assume they are in the same place (same room temperature, same measurement equipment, e.g., scales).
If everything is as identical as possible, and yet they see two different times for the reaction, one might conclude, just looking at the data, that reactions proceed more rapidly when performed by men, as compared to a woman. This leads to a publication in the Journal of the American Chemical Society with the title "Men Provide Catalytic Acceleration in Chemical Reactions." The evidence is clear: An improvement in reaction speed when a reaction is performed by a man. The story will run in Time Magazine, further validating the conclusion.
But although one assumes the conditions were the same for both reactions, there is no evidence they were repeated and shown to be valid for multiple reactions. In reality, Dominic was always a bit competitive, so when he sensed his reaction was nearing completion, he hit the stop watch and recorded the time. Eva waited until she was certain the reaction was complete.
The difference in times was more a function of differences in the individuals. One could also have concluded, in a paper for the Journal of Psychology, that "Men React Prematurely to Timing Challenges."