Read the abstract (you do not need to copy/paste it into your homework assignment) and identify whether each study is a (1) descriptive or (2) scientific/analytic study. For the scientific/analytic studies, also list the exposure(s) and outcome(s) being evaluated.

1. Biino G, Casula L, de Terlizzi F, Adamo M, Vaccargiu S, Francavilla M, Loi D, Casti A, Atzori M, Pirastu M. Epidemiology of osteoporosis in an isolated Sardinian population by using quantitative ultrasound. Am J Epidemiol. 2011 Aug 15;174(4):432-9. Epub 2011 Jun 27. (4 pts)
2. Lu BB, Li KH. Association between ABO Blood Groups and Osteoporosis Severity in Chinese Adults Aged 50 Years and Over. J Int Med Res. 2011;39(3):929-33. (4 pts)c
3. Oyen J, Brudvik C, Gjesdal CG, Tell GS, Lie SA, Hove LM. J Bone Joint Surg Am. 2011 Feb 16;93(4):348-56.Osteoporosis as a risk factor for distal radial fractures: a case-control study. (4 pts)d.
4. Looker AC, Melton LJ 3rd, Harris TB, Borrud LG, Shepherd JA. Prevalence and trends in low femur bone density among older US adults: NHANES 2005-2006 compared with NHANES III. J Bone Miner Res. 2010 Jan;25(1):64-71. (4 pts)