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What is the linear regression equation for the data?
An instructor at Ball State Univ. Asked a random sample of 8 students to record their study times in a beginning statistics course. She then made a table for total hours studied, x, over 2 weeks, and test score, y, at the end of the 2 weeks. Here are the results: x/ 10, 15, 12, 20, 8, 16, 14, & 22. Y is/ 92, 81, 84, 74, 85, 80, 84, & 80.
I'm putting in x list first in L1 and y in L2. When doing the plot, my line suggests a strong negative correlation. What am I doing wrong. According to the table, the more you study, the worse your score would be. Please help me understand what I am doing wrong. Thanks so much!
I get the same result as you.
Please be understood that one of the big concept about regression analysis is that
the y = ax+b does not imply any cause and effect relationship.
It means that even those there is a strong relationship between the variables. It does not imply the reason of Y is due to the happening of X.
The cause and effect relationship needed to be identified by another method.
(One of the reason, for negative relationship may be students do not understand the material need to take a longer time to digest the material but they are not necessary to get a higher grade in test because they may still have a lot of material not yet being digested. This reason is by observation, instead of calculation.)
There is a famous stories in regression analysis. Someone personal income increases every year. Because of fashion trend, people like to keep long hair. Then, as time going, the person hair is also increase every year.
Then if we put the personal income as Y and length of hair as X to build a regression model. Then it also give a very strong positive correlation. But, is it implied that my length of hair is the reason to get person income increase .........
Although it is a joke, it is good enough to let you know the deficiency of regression model.
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