15.15 The paper “Trends in Blood Lead Levels and Blood Lead Testing among U.S. Children Aged 1 to 5 Years” (Pediatrics

[2009]: e376–e385) gave data on blood lead levels (in mg/dL) for samples of children living in homes that had been classified either at low, medium, or high risk of lead exposure based on when the home was constructed. After using a multiple comparison procedure, the authors reported the following:

1. The difference in mean blood lead level between lowrisk housing and medium-risk housing was significant.

2. The difference in mean blood lead level between lowrisk housing and high-risk housing was significant.

3. The difference in mean blood lead level between medium-risk housing and high-risk housing was significant.

Which of the following sets of T-K intervals (Set 1, 2, or 3)

is consistent with the authors’ conclusions? Explain your choice. (Hint: See Example 15.5.)

mL 5 mean blood lead level for children living in lowrisk housing mM 5 mean blood lead level for children living in medium-risk housing mH 5 mean blood lead level for children living in high-risk housing Difference Set 1 Set 2 Set 3 mL 2 mM (20.6, 0.1) (20.6, 20.1) (20.6, 20.1)

mL 2 mH (21.5, 20.6) (21.5, 20.6) (21.5, 20.6)

mM 2 mH (20.9, 20.3) (20.9, 0.3) (20.9, 20.3)