HP 10bII+ - Page 130

Statistical Calculations122
Linear Regression. Calculate r (the correlation coefficient), m, b, and as follows:
1. Clear the statistical registers by pressing \t.
2. Enter the first x-value and press Æ. The x-value is displayed.
3. Enter the corresponding y-value and press ¡. The HP 10bII+ displays n, the number
of pairs of items accumulated.
4. Continue entering x,y pairs. The n-value is increased with each entry.
5. To display r, the correlation coefficient, press \Z\«.
6. To display m, the slope, press \W\«.
7. To display b (the y-intercept), press \T\«.
Linear Estimation. The straight line calculated by linear regression can be used to estimate a
y-value for a given x-value, or vice versa:
1. En t e r t h e x,y data.
2. Enter the known x-value or y-value.
• To estimate x for the given y, enter the y-value, then press \Z.
• To estimate y for the given x, enter the x-value, then press
\W.
Example: 4
Ali’s Azaleas advertises on a local radio station. For the past six weeks, the manager has kept
records of the number of minutes of advertising that were purchased, and the sales for that
week.
What is the y-intercept, the slope, and the correlation coefficient?
Table 12-9 Recording the number of minutes of the advertisements and sales
Week
Minutes of Advertising
(x-values)
Sales
(y-values)
121,400
21 920
33 1,100
452,265
552,890
642,200