Answer :
From this question the hidden variable of the people could be the
- Age
- Which people were selected for the sample
What is a hidden variable?
This is another term for what is referred to as a confounding variable. These are the types of variables that would have an indirect effect on the endogenous variable.
The variables here are the age of the person that is drinking coffee and the people used in the study.
Read more on variables here: https://brainly.com/question/20755331
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