Quality Assurance

Question 1

Quality Assurance

Answer 1

what we do to get the right answer and be confident it is the right answer

Question 2

10 red markers are sampled every hour as they exit the final step of production before mixing and packaging

Answer 2

sampling requirements

Question 3

accuracy

Answer 3

how close to the true value you are

Question 4

what ways is accuracy measured in?

Answer 4

mean, % error

Question 5

precision

Answer 5

how well replicate measurements agree with one another

Question 6

what ways is precision measured in?

Answer 6

confidence interval, standard deviation, relative standard deviation (st. dev. / mean), standard uncertainty

Question 7

false positives

Answer 7

result is positive when it is actually negative

Question 8

false negatives

Answer 8

result is negative when it is actually positive

Question 9

selectivity

Answer 9

extent to which a method can distinguish the analyte from everything else in the sample

Question 10

sensitivity

Answer 10

method or instrument response to changes in sample concentration; change sample concentration a small amount and observe a big change

Question 11

what are the three types of blanks?

Answer 11

instrument, reagent, method/solvent

Question 12

instrument blank

Answer 12

nothing in the instrument

Question 13

what does an instrument blank tell us?

Answer 13

observes the electronic noise

Question 14

reagent blank

Answer 14

one reagent at a time is put into the instrument

Question 15

method/solvent blank

Answer 15

the solvent by itself goes through every step of the experiment

Question 16

what is the purpose of the method/solvent blank?

Answer 16

shows any problem with the method or interactions of solvents

Question 17

what does putting a control sample through the instrument tell us with all the blanks?

Answer 17

with all the blank’s responses, you are able to identify the control sample’s response out of the other three responses

Question 18

four types of precision

Answer 18

instrument, intra-assay, interlaboratory, intermediate

Question 19

instrument precision

Answer 19

a single scientist performs the same experiment with the same sample and the same instrument and takes multiple measurements

Question 20

intra-assay precision

Answer 20

repeatability; the same scientist performs the same procedure on the same day using the same aliquot of the same starting sample using the same instrument multiple times

Question 21

intermediate precision

Answer 21

ruggedness; different scientists in the same lab perform the same procedure using aliquots from the same sample on different days with different instruments

Question 22

interlaboratory precision

Answer 22

reproducibility; aliquots of the same sample are sent to different labs to be analyzed by different scientists with different instruments on different days using the same procedure

Question 23

how reproducible am I when performing the same experiment?

Answer 23

intra-assay precision

Question 24

how reproducible is the experiment when performed with in our lab?

Answer 24

intermediate precision

Question 25

how reproducible is the experiment when performed across different labs?

Answer 25

interlaboratory precision

Question 26

how reproducible is the value that comes from an instrument?

Answer 26

instrument precision

Question 27

most precise to least precise types of precision

Answer 27

Most Precise: instrument intra-assay intermediate Least Precise: interlaboratory

Question 28

before analyzing a red marker, a sample of the solvent without any dye is analyzed; the instrument response must be less than 0.10 AU

Answer 28

method/solvent blank

Question 29

before analyzing a red marker from the production line, three separate solutions of standards of the expected dye concentration are analyzed by the spectrophotometer; the st. dev. of the instrument response must be less than 0.10 AU

Answer 29

using a control sample to measure precision

Question 30

when analyzing each red marker, the instrument response for a single marker was measured three times; the st. dev. for the average instruction response must be less than 0.10 AU

Answer 30

precision

Question 31

when analyzing the ten red markers each hour, the percent error for any single marker must not exceed 1%

Answer 31

accuracy

Question 32

when purchasing a new instrument to perform these analyses, a series of standards of various known concentrations of the red dye are analyzed and the slope of the best fit line determined; the steeper the line, the better

Answer 32

sensitivity

Question 33

what makes a reference source scholarly?

Answer 33

1. published in a scientific journal, access freely or through a library? 2. references cited throughout the text 3. text should be peer-reviewed by other experts in the same area as what the text is focused on