Question

Just because there are high levels of lead in the water does not mean that it is necessarily having a negative effect on people. While the Flint Water Study was conducting their water testing, local pediatrician Dr. Mona Hanna-Attisha investigated blood lead levels in children. Hanna-Attisha predicted that if lead levels in water had increased, she would see higher lead levels in children. She was able to gain access to city medical records from the past several years. With these data, she could investigate if lead levels had increased after the water source switch. Furthermore, she could investigate if wards with the highest amounts of lead in their water also had children with the highest amounts of lead in their blood. Which 3 of the following 6 graphs would best support the hypothesis that lead in the water was causing elevated lead levels in children? Drag a check mark to the three graphs that best support the hypothesis. Drag an X to the three that do not support the hypothesis. (WLL stands for water lead level, and BLL stands for blood lead level.)

Answer 1

(image of the graph is attached)

Answer:

a- √

b-X

c- √

d-X

e- √

f-X

Explanation:

Graph a, c and e best represent the hypothesis that lead in the water was causing elevated lead levels in children.

• Graph a and Graph d

Graph (d) is just the opposite of hypothesis. It shows that before the water switc, high levels of WLL lead to an increase in percentage of children with BLL> 5μg/dl . Hence graph (d) does not support the hypothesis.

On the other hand, Graph (a) clearly shows how after the water switch in Flint, a high WLL lead to an increase in percentage of children with BLL> 5μg/dl, And before the water switch, the levels were much lower as indicated by a smaller bar on the bar graph. Thus supporting the hypothesis.

Graph (b) and Graph (e)

Both graphs shows a straight line indicating that when WLL of a home was increased there was an increase in BLL of a child in a home. However, graph (b) contain less points, which means not much data was collected. Thus not representing clear information regarding the hypothesis. Whereas graph (e) contain many points which means more data was collected and plotted accordingly. Hence graph (e) is accepted.

Graph (c) and Graph (f)

Graph (c) clearly shows how before the water switch, i.e before 2014, the average BLL in children was low, as WLL was also low(since their water supply was coming from the Great lakes,which has low WLL). But after the switch to Flint river in 2014, the average BLL levels increased. Hence supporting the hypothesis.  

Graph (f) does not support the hypothesis, because it shows that before the water switch, there was already an increase in average BLL in children, indicating that WLL were already high even before the water switch. Thus proving the hypothesis wrong. Hence this graph is rejected.