Question

The SAT and the ACT are the two major standardized tests that colleges use to evaluate candidates. Most students take just one of these tests. However, some students take both. The data data34.dat gives the scores of 60 students who did this. How can we relate the two tests?

(a) Plot the data with SAT on the x axis and ACT on the y axis. Describe the overall pattern and any unusual observations.

(b) Find the least-squares regression line and draw it on your plot. Give the results of the significance test for the slope. (Round your regression slope and intercept to three decimal places, your test statistic to two decimal places, and your P-value to four decimal places.)

ACT = ______	+_______ (SAT)
t =_______
P = _______

(c) What is the correlation between the two tests? (Round your answer to three decimal places.) (_______)

obs     sat     act
1       1104    23
2       786     16
3       668     18
4       1062    20
5       1025    21
6       1254    29
7       1183    21
8       908     12
9       837     22
10      695     12
11      1043    21
12      735     18
13      884     17
14      1269    28
15      968     21
16      1034    22
17      1070    25
18      826     19
19      750     16
20      1043    21
21      854     23
22      1063    26
23      866     21
24      1021    18
25      719     10
26      1134    27
27      932     20
28      1069    22
29      904     20
30      839     23
31      998     20
32      672     17
33      1199    26
34      775     22
35      1195    31
36      795     15
37      776     18
38      888     19
39      967     22
40      915     23
41      792     18
42      663     20
43      745     13
44      615     14
45      844     18
46      745     15
47      950     24
48      967     21
49      1258    27
50      983     21
51      915     21
52      1041    19
53      902     25
54      932     23
55      858     16
56      966     22
57      784     18
58      1082    27
59      868     20
60      992     24

Answer 1