Chapter 10 - Summary'

Question 1

All measurements contain _____ and _______

Answer 1

• errors
• uncertainties

Question 2

Always provide, what?

Answer 2

• an estimate of the quality
• reliability of collected data

Question 3

How to improve the reliability of results?

Answer 3

prepare two to five replicate samples

Question 4

What is used as a measure of central value of data?

Answer 4

Use the mean or median of replicates

Question 5

Measure the ______ of data to demonstrate its reproducibility

Answer 5

precision

Question 6

What is more difficult to determine because the true value is seldom known?

Answer 6

Accuracy of results

Question 7

Do not ______ that because measurements are precise, they are also accurate

Answer 7

assume

Question 8

arise from experimental variables that cannot be controlled or determined

Answer 8

Random, or indeterminate, errors

Question 9

occur when instruments or measuring devices are uncalibrated or are calibrated improperly

Answer 9

Systematic, or determinate, errors

Question 10

are caused by nonideal instrument behavior, by faulty calibrations, or by use under inappropriate conditions

Answer 10

Instrumental errors

Question 11

arise from nonideal chemical or physical behavior of analytical systems

Answer 11

Method errors

Question 12

result from the carelessness, inattention, or personal limitations of the experimenter

Answer 12

Personal errors

Question 13

are independent of the size of the sample being analyzed

Answer 13

Constant errors

Question 14

decrease or increase in proportion to the size of the sample

Answer 14

Proportional errors

Question 15

Most personal errors can be minimized by

Answer 15

• careful
• disciplined laboratory work
• careful choice of methods and instruments

Question 16

What is the best way to estimate the bias of an analytical method?

Answer 16

by analyzing standard reference materials (SRMs)

Question 17

contains the solvent and all the reagents in an analysis

Answer 17

blank solution

Question 18

Whenever feasible, _____ may also contain added constituents to simulate the ______ _____

Answer 18

• blanks
• sample matrix

Question 19

It refers to the collection of all the constituents in the sample

Answer 19

Matrix

Question 20

The substance being determined

Answer 20

Analyte

Question 21

occur infrequently and often result from an experimental blunder

Answer 21

Gross errors

Question 22

an occasional result in replicate measurements that differs significantly from the other results

Answer 22

Outlier

Question 23

• measures the systematic error associated with an analysis
• it has a negative sign if it causes the results to be low and positive sign otherwise

Answer 23

Bias

Question 24

determines the relationships between a measured quantity and the analyte concentration

Answer 24

Calibration