http://www.ssu.ac.ir/cms/fileadmin/user_upload/Daneshkadaha/dbehdasht/modiryat_khatamat_behdashti/kotob_farsi/The_economics_of_health_and_health_care-_Sherman_Folland.pdf in Chapter 3 Q 8

8 Consider the estimate demand equation of

Q=1,000-3.3p- 0.2p+0.001Y

(3.5) (2.1) (0.5)

with t values in parentheses, where Pz is the price of another good Z, and Y is income. Is good Z a substitute or a complement? Can we say confidently whether good X is a normal good or an inferior good?