Definitions

Question 1

Analytical chemistry

Answer 1

development of new analytical techniques to make possible relevant measurements for new areas of science… validation and verification of results through calibration and standardization

Question 1

The scientific method

Answer 1

the systematic, organized gathering of data; the objective formulation and testing of hypotheses (ideas, concepts, theories) with that data; and the stating of conclusions that can be evaluated independently by others
- feedback loop

Question 2

Critical thinking

Answer 2

the intellectual habit of objectively assessing information to determine its veracity and hence evaluating its validity when forming and making decisions - a learned skill that requires effort

Question 3

population

Answer 3

the entire data set that fits your parameters

Question 4

sample

Answer 4

a subsection of a population selected using a pre-defined (to remove bias) method that can be used for analysis

Question 5

homogenous

Answer 5

same composition everywhere in the material

Question 6

heterogenous

Answer 6

different composition from place to place in a material

Question 7

sampling

Answer 7

process of collecting a representative sample

Question 8

lot

Answer 8

total material from which samples are taken

Question 9

bulk sample

Answer 9

taken from the lot for analysis and must be representative of the lot

Question 10

laboratory sample

Answer 10

a smaller homogenous sample that has the same composition as the bulk sample

Question 11

aliquots

Answer 11

smaller portions of the laboratory sample that are used for individual analyses

Question 12

random sampling

Answer 12

totally unbiased - true randomness is hard to achieve

Question 13

judgemental sampling

Answer 13

using prior information about the target population to help guide the selection of samples

Question 14

systematic sampling

Answer 14

sample the target population at regular intervals in space or time

Question 15

systematic-judgemental sampling

Answer 15

prior knowledge about a system is used to guide a systematic sampling plan

Question 16

judgemental-random (stratified) sampling

Answer 16

used for target populations consisting of distinct units, or strata, to minimize sampling bias - doing random sampling within each area

Question 17

convenience sampling

Answer 17

sample sites are selected using criteria other than minimizing sampling error and sampling variance

Question 18

accuracy

Answer 18

describes how close a measured value is to the “true” value

Question 19

precision

Answer 19

describes the reproducibility of a result

Question 20

standard reference materials

Answer 20

certified with painstaking care at National Standards Laboratories - the true value to high precision and accuracy

Question 21

repeatability

Answer 21

describes the spread in results when one person uses one procedure to analyze the same sample by the same method multiple times

Question 22

reproducibility

Answer 22

describes the spread in results when different people in different labs using different instruments each try to follow the same procedure

Question 23

error

Answer 23

difference between the true and measured values (a measurement of accuracy)

Question 24

uncertainty

Answer 24

the fluctuation in a value - a measure of precision

Question 25

systematic error

Answer 25

arises from a flaw in the equipment or the design of an experiment - reproducible if you conduct the experiment in exactly the same way again

Question 26

random error

Answer 26

arises from uncontrolled (and maybe uncontrollable) variables in the measurement

Question 27

gross error

Answer 27

extreme instances or random or systematic error, due to accidental but significant departures from procedure

Question 28

absolute uncertainty

Answer 28

expresses the margin of uncertainty associated with a measurement (always has units; the range in uncertainty (+- something)) - how sure you are in a measurement

Question 29

relative uncertainty

Answer 29

compares the size of the absolute uncertainty with the size of its associated measurement (no units)

Question 30

raw data

Answer 30

unchanged data acquired directly from the measurement

Question 31

processed data

Answer 31

data which has been subjected to any type of alteration

Question 32

mean (average)

Answer 32

sum of the measured values divided by the number of measurements

Question 33

standard deviation

Answer 33

measures how closely the data are clustered about the mean (a measure of precision)

Question 34

causation

Answer 34

action A causes outcome B