Biostatistics

500 CHAPTER 10 MULTIPLE REGRESSION AND CORRELATION
Postoperative
Length of
Stay in Days
(Y)
Number of Current
Medical Problems
(X 1 )
Preoperative
Length of
Stay in Days
(X 2 )
12 3 2
8 1 2
9 2 2
Total 208 38 43
10.3.5 A random sample of 25 nurses selected from a state registry yielded the following information on
each nurse’s score on the state board examination and his or her final score in school. Both scores
relate to the nurse’s area of affiliation. Additional information on the score made by each nurse on an
aptitude test, taken at the time of entering nursing school, was made available to the researcher. The
complete data are as follows:
State Board Score
(Y)
Final Score
(X 1 )
Aptitude Test Score
(X 2 )
440 87 92
480 87 79
535 87 99
460 88 91
525 88 84
480 89 71
510 89 78
530 89 78
545 89 71
600 89 76
495 90 89
545 90 90
575 90 73
525 91 71
575 91 81
600 91 84
490 92 70
510 92 85
575 92 71
540 93 76
595 93 90
525 94 94
545 94 94
600 94 93
625 94 73
Total 13,425 2263 2053