In a field experiment to observe altruistic behavior, an observer records the number of people who stopped to hold the door for a student on crutches. she reports that seven people volunteered to assist the young man, when in fact there were only five. she has made an error called:

inaccurate observation

Explanation:

Inaccurate observations occurs when someone doing the observation makes incorrect report of what they actual observed.

This error is more prevalent when we are not paying fully attention to what we are observing.

We are humans and sometimes we get distracted by something that may take our eyes away for a moment or because our mind is thinking about something else and in observation research if one takes their eyes of they can miss out on some aspect that are crucial part of the observation.