Professor izadi is interested in the association between sleep and cognitive performance. he surveyed his students about the number of hours they slept the night before the exam and then correlated these scores with their test grades. he found a +.81 correlation between these two variables. what does this result mean? group of answer choices

There is a high positive correlation between sleep and exam performance.

Explanation:

The concept of correlation indicates an association, that is to say, it is used for measuring how much two variables relate to each other. The 3 results of a correlational study are positive, negative, and no correlation. A positive correlation takes place between 2 variables that can increase or decrease together. In this case, the more students sleep, the better they performed at their exams.

chronological thinking is an indispensable tool to structure a historical narrative and to give meaning to a sequence of events. the final section presents the results of a survey to test the chronological thinking of lower secondary school students carried out by the educational research institute.