Statistical parameters

Combined

Dar es Salaam

Mbeya

Control limits: ±2

Number of samples

124

95

29

(Dar es Salaam + Mbeya)

124

Standard deviation

2.36

2.23

2.68

14.96

Mean

10.23

10.43

9.59

Xbar + 1

12.60

Minimum

5

5

5

X-bar

10.23

Maximum

16

16

15

Xbar-1

7.87

Range

11

11

10

Xbar-2

5.51