The popular method used by researchers in usability study is a method called a direct observation
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What is a direct observation?</h3>
A direct observation refers to a method of collecting data where the researcher watches the subject in his or her natural setting.
The direct observation is also called observational study
In conclusion, the popular method used by researchers in usability study is a method called a direct observation
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The main point for education was to teach them how to fight
He/she is called "insurer" or " assurer".