Dr. ellison finds a relation between amount of sleep and problem solving. specifically, having a higher amount of sleep the night before an exam is associated with higher scores on two measures of problem solving. this is an example of which type of association?

positive association

Explanation:

Positive association refers to the relationship developed between the two variables where the variables tend to move in the same direction. The condition specifies that with the decrease in one variable, the other variable decreases. On the other hand, when one variable increases, the other too increases. According to the given question, Dr. Ellison's research and study sets an example to be a positive association.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.