1.Key statistics from the 2011 Childhood Lead Registry annual survey include:

• Statewide, 109,534 children under the age of 6 were tested, which is a decrease from the 2010 figure of 114,829. In Baltimore City, 19,049 children were tested, a decrease from 19,702 in 2010.
• 452 of these children (or 0.4 percent of those tested) had a blood lead level of 10 micrograms per deciliter (mg/dL) or above. This is lower than the 531 (0.5 percent) in 2010. In Baltimore City, 258 children (1.4 percent of those tested) had a blood lead level of 10 mg/dL or above, which is down from 314 (1.6 percent) in 2009.
• Of the children statewide ... showing a blood lead level of 10 mg/dL or above, 60.3 percent lived in homes other than pre-1950 residential rental units, compared to 60.1 percent in 2010 and 54 percent in 2009. The similar figure for Baltimore City for 2011 was 36.9 percent compared to 40.3 percent in 2010 and 40 percent in 2009."

a.What type of study data is this based on and how can you tell? (2pts)

b.What comparisons are made (name 2)? (2pts)

c.What can you say about the risk of a child moving to Baltimore City having their blood lead level reach the level of 10 mg/dL or over?(2pts)