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Unformatted text preview: Inference Review STAT 3022, section 005 03/11/2011 1. Workers perceptions about safety. The Safety Climate Index (SCI) measures workers perceptions about the safety of their work environment. A study of safe work practices of industrial workers reported mean SCI scores for workers classified by workplace size. Here are the means: Workplace Fewer than 50 to 200 More than size 50 workers workers 200 workers Mean SCI 67.23 70.37 74.83 Assume that the standard deviation is = 19 and the sample sizes are all n = 180. (a) Calculate a 95% confidence interval for each mean. (b) One way to adjust for the fact that we are reporting three confidence intervals is a procedure that uses a larger value of z * in the calculation of the margin of error. For this problem, use z * = 2 . 40. Repeat part (a) making this adjustment. (c) Summarize your results. Be sure to include comments on the effects of the adjustment on your results. 2. Healthy bones study Healthy bones are continually being renewed by two processes. Through bone formation, new bone is built; through bone absorption, old bone is removed. If one or both of these processes are disturbed, by disease, aging, or space travel, for example, bone loss can be the result. Osteocalcin (OC) is a biochemical marker for bone formation: higher levels ofthe result....
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This note was uploaded on 08/31/2011 for the course STAT 3101 taught by Professor Erick during the Spring '11 term at Minnesota.
- Spring '11