Question

The authors of the paper "Statistical Methods for Assessing Agreement Between Two Methods of Clinical Measurement"† compared two different instruments for measuring a person's ability to breathe out air. (This measurement is helpful in diagnosing various lung disorders.) The two instruments considered were a Wright peak flow meter and a mini-Wright peak flow meter. Seventeen people participated in the study, and for each person air flow was measured once using the Wright meter and once using the mini-Wright meter.

Subject	Mini- Wright Meter	Wright Meter	Subject	Mini- Wright Meter	Wright Meter
1	512	494	10	445	433
2	430	395	11	432	417
3	520	516	12	626	656
4	428	434	13	260	267
5	500	476	14	477	478
6	600	557	15	259	178
7	364	413	16	350	423
8	380	442	17	451	427
9	658	650

(a)

Suppose that the Wright meter is considered to provide a better measure of air flow, but the mini-Wright meter is easier to transport and to use. If the two types of meters produce different readings but there is a strong relationship between the readings, it would be possible to use a reading from the mini-Wright meter to predict the reading that the larger Wright meter would have given. Use the given data to find an equation to predict y = Wright meter reading using a reading from the mini-Wright meter. (Round your values to three decimal places.)

ŷ = __+ __x

(b) What would you predict for the Wright meter reading of a person whose mini-Wright meter reading was 523? (Round your answer to three decimal places.)

(c) What would you predict for the Wright meter reading of a person whose mini-Wright meter reading was 348? (Round your answer to three decimal places.)

Answer 1

Excel:

Data --> Data analysis --> Regression

Output:

	Coefficients	Standard Error	t Stat	P-value
Intercept	11.482	41.03931816	0.279775	0.783471
Mini- Wright Meter	0.970	0.088145175	11.00394	1.4E-08

(a) The regression equation is,

y = 11.482+0.970x

(b)  y = 11.482+0.970*523 = 518.792

(c)  y = 11.482+0.970*348 = 349.042