Answer to Question #343291 in General Chemistry for grace

Question

the following set of lead determinations on seperate aliquots of a pooled blood serum were reported 103,106,107 and 114 meq/L.one value appears suspect.should the suspect be retained or discarded at 95% confidence level

Answer 1

X₁= 103 X₂= 106 X₃= 107 X₄= 114 N=4

We use Dixon's Q-test to solve this problem:

1. The values comprising the set of observations under examination are arranged in ascending order:

X₁ < X₂ < X₃ < X₄

2. The statistic experimental Q-value (Q_exp) is calculated. This is a ratio defined as the difference of thesuspect valuefrom itsnearestone divided by the range of the values:

Q_exp = (X₂ - X₁) / (X₄ - X₁) => (106-103) / (114-103) = 3/8 = 0.375

3. The obtained Q_exp value is compared to a critical Q-value (Q_crit) found in tables. This critical value should correspond to the confidence level (CL) we have decided to run the test (CL=95%).

The following figure shows a table of critical values ​​of Q.

4. If Q_exp > Q_crit, then the suspect value can be characterized as an outlier and it can be rejected, if not, the suspect value must be retained and used in all subsequent calculations.

Q_exp = 0,375

Q_crit = 0,829

Q_exp < Q_crit hence, the suspect should be detained

ANSWER: suspect should be detained