MATH
147概念.docx

# 147概念.docx - 147 I Points with second coordinate...

• Notes
• 2

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 147 I Points with second coordinate greater than the ﬁrst lie above the horizontal rising diagonal; points with second coordinate less than the ﬁrst lie below the horizontal rising diagonal. If the horizontal and vertical axes have no units, or if they have the same units, then the slope has no units. However, if the axes have different units, the slope must have corresponding units. For example, if the vertical axis is measured in feet and the horizontal in seconds, then the slope is measured in feet per second. Not surprisingly, the units of slope are a rate. Why the Computation Makes Sense' If you picture the points of the scatter diagram plotted on a graph with standard unit scales, the point of averages lands at the origin. Points in the ﬁrst and third quadrant will have positive products, providing a positive contribution to the average of the products. If these points dominate, i" will be positive. Points in the second and fourth quadrant will have negative products, providing a negative contribution to the average of the products. If these points dominate, 7' will be negative. Pictures May be Deceiving' The appearance of the data in a scatter diagram depends upon the size of the standard unit. The two scatter diagrams belowr both have 1* = .70. The ﬁrst appears to be more tightly clustered around the SD line because the diagram is drawn with a smaller distance representing the standard unit. If the graphs are scaled so that the standard units coincide, it will become apparent that they have the same correlation. Figure 3. The effem oi changing SDS. The two scatter diagrams have the same correlation coefﬁcient 01' {lit}. The top diagram looks me tightly rlustemd around the SI} line bonus: ils SDs In: smaller. «I a 1" all" at" I- I, a . .3" ‘ I: -: ' - s.;..ki~¢.. a :-' "1' '1‘ '.._* it?!" ' v u.:'J-!:n")"={' "u. 3.1.."- t-tI-‘l 1"- and“ 1 ’x - ill-I" f, t- a ,f.’_ 1—.-—.——.-—-.—-.-—.-—. U 1 I 3 l E l 1‘ I I {a " a. ° .' .: 3J1" a a _ i. 1"!!an :- . . .r‘ - .°. ‘ r:- , --'-':,.«’ 1 ‘ I. a f I. I I. ' in." I t a " If" . u s I. u I" ,4- v! 1 '. .' f...” , ",4“. '.‘ . " "=1. , ' a", r ' t! + o I} II I 3 i I II T I Figure 4. Non-linear association. Regression lines should not be used when there is a non-iinear association between the variables. ...
View Full Document

• Fall '07
• Klimko
• Statistics, standard unit, ﬁrst lie

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern