it means to have a great mind
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Time. I wish I had more of it.
The variable is the group that was given caffine, because thats what the doctors manipulated. They possibly altered the natural memory of the participants by giving them caffine. A more specific variable could be how much caffine each participant is given and what time are they given it.
A vertical relationship involves people who don’t share the same status
I believe the answer you're looking for is "Specificity".
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