How can I solve regression questions w/o a graphing calculator?
Eg:-Jack recorded the amount of time he studied the night before each of 4 history quizzes and the score
he got on each quiz. The data are in the table below.
Score Time (min.)
86 45
70 15
90 40
78 35
Use linear regression to estimate the score Jack would get if he studied for 20 minutes.
(A) 71
(B) 72
© 73
(D) 74
(E) 75
Is B the right answer? I would try and make a graph and a line of best fit through the points?
@mommdc Yes
Method?
@UAS998 unless you really trust your drawing abilities, I strongly suggest using a graphing calculator for this question. I drew a graph and couldn’t immediately determine (for sure) what the best answer is.
You can also determine the equation of the line manually by knowing that the slope of the least squares line is Cov[x,y]/Var[x] but the computation becomes messy for an SAT problem.
@MITer94 Oh…
Thanks for the help!
Yes I drew the graph and then kind of guessed because the numbers were real close to each other. I guess I got lucky.
Excel.
@UAS998 I got that the equation of the least squares regression line is y = 60.506 + 0.607x where x is time spent in minutes, and y is score.
If x = 20, then y = 60.506 + 0.607*20 = 72.646 which is closer to 73. I am sure I inputted the data correctly.
This is why I suggested using a calculator.