Parameter

²²⁶Ra (mBq/L)

²²⁸Ra (mBq/L)

37.0 ± 1.0

185.0 ± 5.0

34.9 ± 0.8

174.3 ± 3.9

Measured mean (mBq/L)

36.8

182.6

37.9

187.1

Measured std. dev. (mBq/L)

5.6

23.3

9.0

12.5

E_n score (95% CL)

−0.02

−0.05

0.17

0.49

Degrees of freedom

8

10

9

7

Observed χ²

1.2

11.1

3.0

2.9

Calculated χ²

20.1

23.2

21.7

18.5