An expert criminalist and a recent trainee both participate

An expert criminalist and a recent trainee both participate in a quality assurance exercise for certification by ASCLD/LAB. They are given a standard sample of alcohol in water at a nominal stated concentration of 15.0000 ppt. Both measure the concentration using 10 replicates with the following results.

Question: Report the 95% confidence limits for both the expert and the trainee.

Run #

Expert

Trainee

1

13.50

14.25

2

13.96

14.46

3

13.16

12.05

4

13.88

13.50

5

14.24

13.32

6

13.95

15.42

7

14.16

13.91

8

14.45

15.63

9

13.81

17.27

10

14.03

14.38

Avg

13.91

14.42

Std Dev

0.37

1.44

Table of Ciritical Values of Student-t

df

90%

95%

99%

1

6.31

12.7

63.7

2

2.92

4.3

9.92

3

2.35

3.18

5.84

4

2.13

2.78

4.6

5

2.02

2.57

4.03

6

1.94

2.45

3.71

7

1.9

2.36

3.5

8

1.86

2.31

3.36

9

1.83

2.26

3.25

10

1.81

2.23

3.17

Infinity

1.64

1.96

2.58

Run #	Expert	Trainee
1	13.50	14.25
2	13.96	14.46
3	13.16	12.05
4	13.88	13.50
5	14.24	13.32
6	13.95	15.42
7	14.16	13.91
8	14.45	15.63
9	13.81	17.27
10	14.03	14.38
Avg	13.91	14.42
Std Dev	0.37	1.44

Solution